Isuzu Hombre S 1997 - 1997 ENGINE PERFORMANCE Self-Diagnostics - Hombre - 2.2L

Isuzu Hombre S 1997 - INTRODUCTION

NOTE:

The CHECK ENGINE light is now referred to as Malfunction Indicator Light (MIL). The MIL is displayed in instrument cluster as CHECK ENGINE.

If no faults were found while performing Basic Diagnostic Procedures, proceed with self-diagnostics. If no Diagnostic Trouble Codes (DTCs) are present after entering self-diagnostics, proceed to TESTS W/O CODES article for diagnosis by symptoms.

Isuzu Hombre S 1997 - SYSTEM DESCRIPTION

The PCM monitors engine operation. It also contains a self-diagnostic system which stores Diagnostic Trouble Codes (DTCs) and compares them to On-Board Diagnostics Generation II (OBD-II) standards.

The goal of OBD-II regulation is to provide vehicle with an on-board diagnostic system which is capable of continuously monitoring the efficiency of emission control systems, and to improve diagnosis and repair when system failures occur.

The Federal Test Procedure (FTP) sets maximum allowable emission standards. A Malfunction Indicator Light (MIL) must illuminate if a system or component either fails or deteriorates to a point where the vehicles emissions could rise above 1 1/2 times FTP standards.

DTCs may only be retrieved using an On-Board Diagnostic (OBD-II) scan tester.

Isuzu Hombre S 1997 - TRIP DETECTION LOGIC

Generation II data streams are prioritized. When two messages attempt to establish communications on a data line at the same time, only the message with higher priority will continue. A new segment of the software called the Diagnostic Executive coordinates the protocol for recording and displaying diagnostic procedures.

After engine has reached normal operating temperature, Diagnostic Executive checks if On Board Diagnostic Tests have been completed since last ignition cycle. It checks if tests have passed during current ignition cycle. Checks if fault identified by diagnostic tests is currently active. It also checks if fault identified has been active during current ignition cycle and what operating conditions were present at the time of failure.

Isuzu Hombre S 1997 - Each test is separated in to four types:

Type A - Turns the MIL on the first time an emission related failure occurs. The MIL will FLASH at a rate of once per second to alert the operator of potentially damaging levels of misfire, such that could destroy the catalytic converter.
Type B - Will only turn MIL on if an emission related condition occurs during two consecutive driving cycles. Conditions such as incorrect fuel trim will be stored in the Freez-Frame data until the fault is detected a second time. If the fault is not detected during three consecutive driving cycles, the MIL light will be turned off.
Type C - This is a non-emission related type and will not activate the MIL. It will turn ON a Check Transmission service light, or other non MIL service reminder light.
Type D - Is non-emission related, will not turn the MIL or service light, but will store DTCs of faults present.

Isuzu Hombre S 1997 - SELF-DIAGNOSTIC SYSTEM HARD FAILURES

Hard failures cause Malfunction Indicator Light (MIL) to glow and remain on until problem is repaired. If light comes on and remains on (light may flash) during vehicle operation, cause of malfunction must be determined using diagnostic (code) charts. See DIAGNOSTIC TROUBLE CODE DEFINITIONS. If a sensor fails, Powertrain Control Module (PCM) will use a substitute value in its calculations to continue engine operation. In this condition, commonly known as limp-in mode, vehicle runs but driveability will not be optimum.

Isuzu Hombre S 1997 - INTERMITTENT FAILURES

Intermittent failures may cause MIL to flicker or glow and go out after intermittent fault goes away. However, corresponding DTC will be retained in PCM memory. If related fault does not reoccur within a certain time frame, related DTC will be erased from PCM memory. Intermittent failures may be caused by a sensor, connector or wiring related problems. See INTERMITTENTS in TROUBLE SHOOTING article.

Isuzu Hombre S 1997 - FREEZE-FRAME DATA

According to the 1996 government regulations, engine operating conditions where MIL is illuminated must be recorded. This record, called freeze frame data, is a snap shot of the driving conditions, that is recorded on the PCM freeze frame buffer and is constantly updated with the most current information.

Freeze frame data can only be overwritten with misfire or fuel trim malfunction data. The data can only be erased by clearing associated history DTCs.

Isuzu Hombre S 1997 - DATA LINK CONNECTOR LOCATION

Located at lower left side of instrument panel, behind a small cover.

Isuzu Hombre S 1997 - RETRIEVING CODES

NOTE:

Codes can be retrieved using a scan tester. Trouble codes are referred to as DTCs.

Code retrieval starts with diagnostic circuit check. See DIAGNOSTIC CIRCUIT CHECK. MIL will come on when ignition is on and engine is not running. When engine is started, MIL should go off. If light remains on while engine is running, a DTC is present.
If light does not come on with ignition on and engine off, inspect MIL circuit before continuing. If MIL fails to operate, see DIAGNOSTIC CIRCUIT CHECK.
To retrieve codes, install scan tool. Select MIL dash lamp control and command the MIL OFF. Ensure MIL light is off and attempt to start engine. If vehicle dos not start, go to vehicle NO-START tests.

Isuzu Hombre S 1997 - CLEARING CODES

After repairs are performed, clear PCM memory of all stored codes. Ensure ignition is off. To clear codes, use diagnostic scan tool "clear DTCs" or "clear info" function. Follow instructions supplied by tool manufacturer, when clearing DTCs.
DTCs can also be cleared by disconnecting any PCM power source or negative battery cable for at least 30 seconds. However, if disconnecting battery remember that other memory functions (clock, radio, etc.) will need to be reset.

Isuzu Hombre S 1997 - PCM REPROGRAM PROCEDURE

If PCM requires replacement PCM must be reprogrammed using a Tech I or other OBD II compatible scan tool.

Isuzu Hombre S 1997 - PCM LOCATION

PCM is located in engine compartment on right fenderwell near hood.

NOTE:

If any DTCs not listed here are displayed by a scan tool, the scan tool data may be faulty. Notify the scan tool manufacturer of any DTCs displayed that are not included in the following table.

Isuzu Hombre S 1997 DIAGNOSTIC TROUBLE CODE DEFINITIONS

DTC

Type⁽¹⁾

Component/System

Most Likely Cause

P0106

MAP Sensor Circuit Range/ Performance Problem

MAP Sensor

P0107

MAP Sensor Circuit Low Frequency

Open/Short, MAP Sensor Or PCM

P0108

MAP Sensor Circuit High Frequency

Open, MAP Sensor Or PCM

P0112

IAT Sensor Circuit Low Frequency

Short, IAT Sensor Or PCM

P0113

IAT Sensor Circuit High Frequency

Open, IAT Sensor Or PCM

P0117

ECT Sensor Circuit Low Frequency

Short, ECT Sensor Or PCM

P0118

ECT Sensor Circuit High Frequency

Open, ECT Sensor Or PCM

P0121

TP Sensor Circuit Range/ Performance Problem

TP Sensor Or PCM

P0122

TP Sensor Circuit Low Frequency

Open/Short, TP Sensor Or PCM

P0123

TP Sensor Circuit High Frequency

Open Circuit, TP Sensor Or PCM

P0125

ECT Sensor Circuit Excessive Warm-Up Time To Closed Loop

Cooling System, ECT Or PCM

P0131

Bank 1 Primary HO2S Circuit Low Voltage

Short, HO2S Sensor, Fuel Supply Or PCM

P0132

Bank 1 Primary HO2S Circuit High Voltage

Open, HO2S Sensor Or PCM

P0133

Bank 1 Primary HO2S Slow Response

HO2S Sensor Or Exhaust System

P0134

Bank 1 Primary HO2S Insufficient Activity

Poor Connections, HO2S Sensor Or PCM

P0137

Bank 1 Secondary HO2S Circuit Low Voltage

Short, HO2S Or PCM

P0138

Bank 1 Secondary HO2S Circuit High Voltage

Open, HO2S Or PCM

P0140

Bank 1 Secondary HO2S Circuit Insufficient Activity

Short In Circuit, HO2S Or PCM

P0141

Bank 1 Secondary HO2S Circuit Malfunction

Open/Short In Heater Circuit Or PCM

P0171

Bank 1 System Too Lean

Fuel Supply/ Contamination, Primary HO2S, MAP, Leaking Exhaust Or Valve Clearance

P0172

Bank 1 System Too Rich

Fule Supply, Primary HO2S, MAP Sensor, Fuel Contamination Or Valve Clearance

P0200

Injector Control Circuit

Open/Short, Faulty Injector Or PCM

P0218⁽²⁾

Transmission High Temp. Condition(A/T Only)

Miscellaneous

P0300

Random Misfire Detected

Ignition System, Fuel Supply, MAP Sensor, EGR System Detected System, IAC Valve Or Contaminated Fuel

P0301

Cylinder No. 1 Misfire Detected

Miscellaneous

P0302

Cylinder No. 2 Misfire Detected

Miscellaneous

P0303

Cylinder No. 3 Misfire Detected

Miscellaneous

P0304

Cylinder No. 4 Misfire Detected

Miscellaneous

P0325

Knock Sensor (KS) Circuit Malfunction

PCM

P0335

Crankshaft Position (CKP) Sensor Circuit Malfunction

CKP Sensor, Circuit Or PCM

P0341

CMP Circuit Performance

Open/Short, CMP Sensor, Faulty Or Missing CMP Magnet OR PCM

P0342

CMP Sensor Low Frequency

CMP Sensor/Magnet Or PCM

P0401

Insufficient EGR Flow Detected

EGR Valve Or Line

P0404

EGR Valve Pintle Position Open

EGR Valve, EGR Valve Circuit Or PCM

P0405

EGR Valve Sensor Signal Low

EGR Valve, EGR Valve Circuit Or PCM

P0420

Bank 1 Catalyst System Efficiency Below Threshold

Catalytic Converter Or Secondary HO2S

P0440

EVAP System

Canister Purge Valve,Vent Solenoid Or Hoses

P0442

EVAP Small Leak Detected

Vent Solenoid, Fuel Cap Or Lines

P0446

EVAP Canister Vent Blocked

Vent Solenoid Or Canister

P0460

EVAP Fuel Level Sensor Circuit

Miscellaneous

P0480

.....

Fuel Level Sensor Circuit High Voltage

Fuel Level Sensor/ Circuit Or PCM/VCM

P0502

VSS Circuit Low Frequency

Open/Short, VSS Or PCM

P0506

Idle Control System Low RPM

IAC Valve Or PCM

P0506

Idle Control System High RPM

IAC Valve Or PCM

P0507

A/C Refrigerant Pressure Sensor Circuit

Open, A/C Refrigerant Pressure Sensor Or PCM

P0530

System Voltage Malfunction (A/T Only)

Miscellaneous

P0562

System Voltage Low

Open Or PCM

P0563

System Voltage High

PCM

P0601

Powertrain Control module (PCM) Memory Check Sum Error

PCM

P0602

PCM Not Programmed

PCM

P0704⁽²⁾

Clutch Switch Circuit

Clutch Switch/ Circuit Or VCM

P0705⁽²⁾

Transmission Range Sensor Circuit Malfunction

Miscellaneous

P0706⁽²⁾

Transmission Range Sensor Rationality

Miscellaneous

P0712⁽²⁾

Transmission Fluid Temperature Low Voltage

Miscellaneous

P0713⁽²⁾

Transmission Fluid Temperature High Voltage

Miscellaneous

P0719⁽²⁾

Brake Switch Circuit Low

Miscellaneous

P0722⁽²⁾

Output Speed Sensor Circuit No Signal

Miscellaneous

P0723⁽²⁾

Output speed Sensor Circuit Intermittent Signal

Miscellaneous

P0724⁽²⁾

Brake Switch Circuit High

Miscellaneous

P0730⁽²⁾

Wont Shift Between 1/2nd, 2/3rd, 2/4th. Stuck in 1st Or 4th gears (A/T)

Faulty Shift Control System

P0742⁽²⁾

Torque Converter Clutch Circuit Stuck On

Miscellaneous

P0748⁽²⁾

Transmission Pressure Control Solenoid Electrical Circuit Fault

Miscellaneous

P0751⁽²⁾

Transmission Shift Solenoid "A" Performance Or Stuck Off (A/T Only)

Miscellaneous

P0753⁽²⁾

Transmission Shift Solenoid "A" - Electrical Circuit Fault

Open/Short In Circuit Or Faulty Solenoid

P0756⁽²⁾

Transmission Shift Solenoid "B" Performance Stuck Off (A/T Only)

Miscellaneous

P0758⁽²⁾

Transmission Shift Solenoid "B" - Electrical Circuit Fault

Open/Short In Circuit Or Faulty Solenoid

P1133

Bank 1 Primary HO2S Circuit Insufficient Switching

Exhaust Leak, Short In Circuit, HO2S Or PCM

P1171

Fuel System Lean During Acceleration

Fuel Pressure, Incorrect Fuel Or Hot Fuel

P1336

.....

CKP System Variation Not Learned

Miscellaneous

P1380

ABS DTC Detected Rough Road Data Unusable

PCM

P1381

CPS Intermittent Interruption

CYP Sensor

P1404

EGR Valve Closed Pintle Position

EGR Valve/Circuit Or PCM

P1406

Exhaust Gas Recirculation (EGR) Valve Pintle Position Circuit

Open/Short, EGR Or PCM

P1441

Evaporative Emission (EVAP) System Flow During Non-Purge

Short, PCM, EVAP Purge Solenoid Or EVAP Vacuum Switch

P1520

.....

Park Neutral Position (PNP) Switch Circuit

PNP Switch Or Circuit

P1601

.....

Serial Communication Malfunction

PCM Or Data Bus

P1602

.....

EBCM/EBTCM Serial Data Circuit

PCM Or Data Bus

P1621

.....

PCM Memory Performance

PCM

⁽¹⁾	See TRIP DETECTION LOGIC for Type Definitions.

⁽²⁾	See appropriate ELECTRONIC CONTROLS article in AUTOMATIC TRANSMISSIONS section.

Isuzu Hombre S 1997 - CIRCUIT TESTING

NOTE:

If PCM requires replacement, PCM must be reprogrammed using a Tech I or other OBD II compatible scan tool. For PCM harness connector and terminal identifications, see appropriate PIN VOLTAGE CHARTS article.

Isuzu Hombre S 1997 - DTC P0106 - MAP SENSOR SYSTEM PERFORMANCE

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

Powertrain Control Module (PCM) supplies a 5-volt reference signal and a ground circuit to Manifold Absolute Pressure (MAP) sensor. As manifold pressure changes, monitored MAP sensor signal voltage changes. MAP sensor signal voltage should be 1.0-1.5 volts at idle and 4.5-4.8 volts at Wide Open Throttle (WOT).

Isuzu Hombre S 1997 - Diagnostic Aids

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
Turn ignition on, with engine off. Using scan tool, compare BARO reading with a know-good vehicle. If BARO reading is normal for the altitude, go to next step. If not, go to step 8).
Start engine while watching MAP sensor value. If MAP sensor value changes, go to next step. If not, go to step 5).
With engine still running, snap throttle while watching MAP sensor display on scan tool. If MAP sensor value change rapidly with throttle position changes, go to step 9). If not, go to step 6).
Disconnect MAP sensor vacuum hose. Install and hand-held vacuum pump to MAP sensor. Turn ignition on, with engine off. Apply 15 in. Hg to MAP sensor. Monitor MAP sensor value on scan tool. If MAP sensor value changes, go to step 7). If not, go to step 8).
Remove MAP sensor vacuum hose from manifold port. Inspect port and hose for restriction. Repair as necessary. After repairs, go to step 9). If no problems were found, go to step 8).
Repair restriction in MAP sensor vacuum hose or port. After repairs, go to step 9).
Replace MAP sensor. After replacing sensor, go to step 9).
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Drive vehicle at a steady speed. Select SPECIFIC DTC function then enter DTC P0106. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Isuzu Hombre S 1997 - DTC P0107 - MAP SENSOR CIRCUIT LOW VOLTAGE

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

Isuzu Hombre S 1997 - Conditions required to test for DTC are:

MAP is less than 14 kPa.
Engine speed less than 1200 RPM.
Throttle Position (TP) sensor angle greater than 16 percent.
DTC P0122 or P0123 not set.

Isuzu Hombre S 1997 - Diagnostic Aids

Turn ignition on, with engine off. MAP sensor voltage signal should be 4.5-4.8 volts. Compare this reading with a known-good vehicle with same style MAP sensor. Voltage readings should be within .4 volt of each other. After repairs are completed, use scan tool and access FUEL TRIM RESET function. Reset long term fuel trim to 128.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
Start and run engine at idle. Using scan tool, observe MAP sensor voltage. If voltage is less than .25 volt, go to next step. If voltage is not less than .25 volt, go to step 4).
Turn ignition off. Disconnect MAP sensor connector. Connect a jumper wire between signal circuit and 5-volt reference circuit terminals at MAP sensor harness connector. Turn ignition on. Observe scan tool. If voltage is greater than 4.7 volts, go to step 5). If voltage is not greater than 4.7 volts, go to step 6).
Ensure ignition is on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. If MAP sensor voltage is less than .25 volt, go to step 3). If MAP sensor voltage is not less than .25 volt, see DIAGNOSTIC AIDS.
Disconnect and inspect MAP sensor connector. If connector is okay, go to step 9). If connector is not okay, go to step 8).
Turn ignition off. Disconnect jumper wire from MAP sensor connector. Connect a test light between positive battery terminal and signal circuit terminal at MAP sensor harness connector. Turn ignition on. Observe scan tool. If MAP sensor voltage is not less than 4 volts, go to step 12). If MAP sensor voltage is greater than 4 volts, go to next step.
Check MAP sensor 5-volt reference circuit for an open or short to ground. If 5-volt reference circuit is okay, go to step 11). If 5-volt reference circuit is not okay, go to step 10).
Repair connector pins and/or wiring as necessary. After repairs, go to step 14).
Replace MAP sensor. After replacing sensor, go to step 14).
Repair 5-volt reference circuit. After repairs, go to step 14).
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to step 14).
Check MAP sensor signal circuit for an open or short to ground. If sensor signal circuit is okay, go to step 11). If sensor signal circuit is not okay, go to next step.
Repair MAP sensor signal circuit. After repairs, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start and warm engine to normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0107. If scan tool indicates TEST RAN AND PASSED, repair is complete. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).

Isuzu Hombre S 1997 - DTC P0108 - MAP SENSOR CIRCUIT HIGH VOLTAGE

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

Powertrain Control Module (PCM) supplies a 5-volt reference signal and a ground circuit to Manifold Absolute Pressure (MAP) sensor. PCM monitors a signal circuit from MAP sensor. As manifold pressure changes, MAP sensor signal voltage changes. MAP sensor signal voltage should be 1.0-1.5 volts at idle and 4.5-4.8 volts at Wide Open Throttle (WOT).

Isuzu Hombre S 1997 - Conditions for setting DTC are:

MAP sensor is greater than 82 kPa.
Vehicle speed sensor less than one MPH.
Throttle Position (TP) sensor angle less than 12 percent.
Engine run time is greater than 20-40 seconds.
DTC P0122 or P0123 not set.

Isuzu Hombre S 1997 - Diagnostic Aids

Turn ignition on, with engine off. MAP sensor voltage signal should be 4.5-4.8 volts. Compare this reading with a known-good vehicle with same style MAP sensor. Voltage readings should be within .4 volt of each other. Check 5-volt reference for short to battery voltage. After repairs are completed, use scan tool and access FUEL TRIM RESET function. Reset long term fuel trim to 128.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
Start and run engine at idle. Using scan tool, observe MAP sensor voltage. If voltage is 4 volts or greater, go to next step. If voltage is not greater than 4 volts, go to step 4).
Turn ignition off. Disconnect MAP sensor connector. Turn ignition on. Using scan tool, observe MAP sensor voltage. If voltage is one volt or less, go to step 5). If voltage is not one volt or less, go to step 6).
Ensure ignition is on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. If MAP sensor voltage is 4 volts or greater, go to step 3). If MAP sensor voltage is not greater than 4 volts, see DIAGNOSTIC AIDS.
Using test light connected to battery voltage, probe MAP sensor signal ground circuit. If test light illuminates, go to step 7). If test light does not illuminate, go to step 9).
Check MAP sensor signal circuit for a short to voltage. Repair as necessary. After repairs, go to step 14). If circuit is okay, go to step 12).
Using DVOM connected to ground, probe 5-volt reference circuit. If DVOM reads about 5 volts, go to next step. If not, go to step 9).
Check for plugged or leaking MAP sensor vacuum hose. Repair as necessary. After repairs, go to step 10). If vacuum hose is okay, go to step 13).
Check 5-volt reference circuit for short to voltage. Repair as necessary. After repairs, go to step 14). If circuit is okay, go to step 12).
Repair vacuum source. After repairs, go to step 14).
Check for open in MAP sensor ground circuit. Repair as necessary. After repairs, go to step 14).
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to step 14).
Replace MAP sensor. After replacing sensor, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start and warm engine to normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0108. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Isuzu Hombre S 1997 - DTC P0112 - IAT SENSOR CIRCUIT LOW VOLTAGE

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

Powertrain Control Module (PCM) supplies and monitors a 5-volt reference signal and a ground circuit to Intake Air Temperature (IAT) sensor. When intake air is cold, sensor resistance is high and when intake air is warm, sensor resistance low. When PCM senses a signal voltage lower (temperature higher) than the normal operating range of the sensor, DTC will set.

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

Engine run time is greater than 6 minutes.
Vehicle speed greater than 15 MPH.
IAT sensor signal voltage indicates IAT is greater than 262?F (128?C).

Isuzu Hombre S 1997 - Diagnostic Aids

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation.

If other DTCs are set for components that share the same ground and/or 5-volt reference circuit, check for faulty connections or wiring. PCM 5-volt reference circuits are internally connected within PCM.

If engine is allowed to sit overnight, ECT and IAT sensor values should be within a few degrees of each other. If sensor temperatures are not within a few degrees of each other, test IAT sensor. See IAT TEMPERATURE-TO-RESISTANCE VALUES.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
Turn ignition on, with engine off. Using scan tool, observe IAT sensor value. If IAT sensor value is greater than 262?F (128?C), go to step 4). If IAT sensor value is not greater than 262?F (128?C), go to next step.
Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Note IAT sensor value displayed on scan tool. If IAT sensor value is greater than 262?F (128?C), go to next step. If IAT value is not greater than 262?F (128?C), no problem is indicated at this time. Go to DIAGNOSTIC AIDS.
Disconnect IAT sensor connector. Note IAT sensor value displayed on scan tool. If IAT sensor value is less than -22?F (-30?C), go to next step. If IAT sensor value is not less than -22?F (-30?C), go to step 6).
Replace IAT sensor. After replacing sensor, go to step 9).
Connect a test light between positive battery terminal and signal circuit terminal at IAT sensor connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 8).
Repair short to ground in IAT sensor signal circuit. After repairs, go to step 9).
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start and warm engine to normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0112. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Isuzu Hombre S 1997 - IAT TEMPERATURE-TO-RESISTANCE VALUES

Isuzu Hombre S 1997 IAT TEMPERATURE-TO-RESISTANCE VALUES

Temperature ?F (?C)	Ohms
212 (100)	177
194 (90)	241
158 (70)	467
122 (50)	973
104 (40)	1459
86 (30)	2238
68 (20)	3520
50 (10)	5670

Isuzu Hombre S 1997 - DTC P0113 - IAT SENSOR CIRCUIT HIGH VOLTAGE

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

Powertrain Control Module (PCM) supplies and monitors a 5-volt reference signal and a ground circuit to Intake Air Temperature (IAT) sensor. When intake air is cold, sensor resistance is high and when intake air is warm, sensor resistance low. When PCM senses a signal voltage lower than the normal operating range of the sensor, DTC will set.

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

Engine run time is greater than 6 minutes.
Vehicle speed greater than 15 MPH.
IAT sensor signal voltage indicates air temperature is less than -40?F (-40?C).

Isuzu Hombre S 1997 - Diagnostic Aids

An intermittent problem can be caused by misrouted harness, rubbed through wire insulation or broken wire inside insulation.

If other DTC(s) are set for components that share the same ground and/or 5-volt reference circuit, check for faulty connections or wiring. PCM 5-volt reference circuits are internally connected within PCM.

If engine is allowed to sit overnight, ECT and IAT sensor values should be within a few degrees of each other. If temperatures are not within a few degrees of each other, test IAT sensor. See IAT TEMPERATURE-TO-RESISTANCE VALUES.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
Turn ignition on, with engine off. Using scan tool, observe IAT sensor value. If IAT sensor value is less than -22?F (-30?C), go to step 4). If IAT sensor value is not less than -22?F (-30?C), go to next step.
Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Note IAT sensor value displayed on scan tool. If IAT sensor value is less than -22?F (-30?C), go to next step. If IAT value is not less than -22?F (-30?C), see DIAGNOSTIC AIDS.
Disconnect IAT sensor connector. Connect a jumper wire between signal circuit and sensor ground circuit terminals at IAT sensor harness connector. Note IAT sensor value displayed on scan tool. If IAT sensor value is greater than 266?F (130?C), go to step 6). If IAT sensor value is not greater than 266?F (130?C), go to next step.
Connect a jumper wire between ground and signal circuit terminal at IAT sensor harness connector. Note IAT sensor value displayed on scan tool. If IAT sensor value is greater than 266?F (130?C), go to step 7). If IAT sensor value is not greater than 266?F (130?C), go to step 8).
Disconnect and inspect IAT sensor harness connector. Repair connector/terminals as necessary. After repairs, go to step 12). If connector is okay, go to step 10).
Check for an open IAT sensor ground circuit. Repair wiring as necessary. After repair is completed, go to step 12). If circuit is okay, go to step 9).
Check for an open IAT sensor signal circuit. Repair wiring as necessary. After repair is completed, go to step 12). If circuit is okay, go to next step.
Check for poor IAT sensor ground or a poor IAT sensor signal circuit terminal connection at PCM. Repair as necessary. After repair is completed, go to step 12). If circuits are okay, go to step 11).
Replace IAT sensor. After repair is completed, go to step 12).
Replace PCM. Program replacement PCM using required equipment. After replacement is completed, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start and warm engine to normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0113. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Isuzu Hombre S 1997 - DTC P0117 - ECT SENSOR CIRCUIT LOW VOLTAGE

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

Powertrain Control Module (PCM) supplies and monitors a 5-volt reference signal and a ground circuit to Engine Coolant Temperature (ECT) sensor. With engine cold, sensor resistance is high and when engine is warm, sensor resistance is low. When PCM senses a signal voltage lower than the normal operating range of the sensor, DTC will set.

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

Engine run time is greater than 2 minutes.
ECT sensor signal voltage indicates engine coolant temperature is greater than 280?F (138?C).

Isuzu Hombre S 1997 - Diagnostic Aids

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation.

If engine is allowed to sit overnight, ECT and IAT sensor values should be within a few degrees of each other. If temperatures are not within a few degrees of each other, test ECT sensor. See ECT TEMPERATURE-TO-RESISTANCE VALUES.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
Turn ignition on, with engine off. Using scan tool, observe ECT sensor value. If ECT sensor value is greater than 266?F (130?C), go to step 4). If ECT sensor value is not greater than 266?F (130?C), go to next step.
Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Using scan tool, observe ECT sensor value. If ECT sensor value is greater than 266?F (130?C), go to next step. If ECT sensor value is not greater than 266?F (130?C), see DIAGNOSTIC AIDS.
Disconnect ECT sensor connector. Observe ECT sensor value. If ECT sensor value is less than -22?F (-30?C), go to step 6). If ECT sensor value is not less than -22?F (-30?C), go to next step.
Check for short to ground in ECT sensor signal circuit. Repair wiring as necessary. After repairs, go to step 8). If circuit is okay, go to step 7).
Replace ECT sensor. After replacing sensor, go to step 8).
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Using scan tool, select CLEAR DTCs or CLEAR INFO function to clear DTCs. Start and warm engine to normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0117. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, return to step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Isuzu Hombre S 1997 ECT TEMPERATURE-TO-RESISTANCE VALUES

Temperature ?F (?C)	Ohms
212 (100)	177
194 (90)	241
158 (70)	467
122 (50)	973
104 (40)	1459
86 (30)	2238
68 (20)	3520
50 (10)	5670

Isuzu Hombre S 1997 - DTC P0118 - ECT SENSOR CIRCUIT HIGH VOLTAGE

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

Engine run time is greater than 2 minutes.
ECT sensor signal voltage indicates engine coolant temperature is less than -40?F (-40?C).

Isuzu Hombre S 1997 - Diagnostic Aids

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation. If other DTCs are set for components that share the same ground and/or 5-volt reference circuit, check for faulty connections or wiring. PCM 5-volt reference circuits are internally connected within PCM.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
Turn ignition on, with engine off. Using scan tool, observe ECT sensor value. If ECT sensor value is less than -22?F (-30?C), go to step 4). If ECT sensor value is not less than -22?F (-30?C), go to next step.
Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Using scan tool, observe ECT sensor value. If ECT sensor value is less than -22?F (-30?C), go to next step. If ECT sensor value is not less than -22?F (-30?C), go to DIAGNOSTIC AIDS.
Disconnect ECT sensor connector. Connect a jumper wire between signal circuit and sensor ground circuit terminals at ECT sensor harness connector. If ECT sensor value is greater than 266?F (130?C), go to step 6). If ECT value is not greater than 266?F (130?C), go to next step.
Connect a jumper wire between ground and signal circuit terminal at ECT sensor harness connector. If ECT sensor value is greater than 266?F (130?C), go to step 7). If ECT sensor value is not greater than 266?F (130?C), go to step 8).
Disconnect and inspect ECT sensor connector. Repair connector as necessary. After repairs, go to step 12). If connector is okay, go to step 10).
Check for open ECT sensor ground circuit. Repair as necessary. After repairs, go to step 12). If circuit is okay, go to step 9).
Check for open ECT sensor signal circuit. Repair wiring as necessary. After repairs, go to step 12). If circuit is okay, go to next step.
Check for poor ECT sensor ground or a poor ECT sensor signal circuit terminal connection at PCM. Repair as necessary. After repairs, go to step 12). If circuits are okay, go to step 11).
Replace ECT sensor. After replacing sensor, go to step 12).
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start and warm engine to normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0118. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Isuzu Hombre S 1997 - DTC P0121 - TP SENSOR SYSTEM PERFORMANCE

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

Powertrain Control Module (PCM) supplies a 5-volt reference signal and a ground circuit to Throttle Position (TP) sensor, and monitors the TP signal circuit for changes in throttle angle. TP sensor signal voltage should be about .5 volt at idle and 4.5 volts or greater at wide open throttle.

Isuzu Hombre S 1997 - Conditions required to test for DTC are:

TP sensor angle is greater than 60 percent at 1600 RPM.
TP sensor angle is greater than 77 percent at 2400 RPM.
TP sensor angle is greater than 89 percent at 3200 RPM.
TP sensor angle is greater than 99 percent at 4000 RPM.

Isuzu Hombre S 1997 - Diagnostic Aids

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation. If other DTC(s) are set for components that share the same ground and/or 5-volt reference circuit, check for faulty connections or wiring. The PCM 5-volt reference circuits are internally connected within PCM. Also, using FREEZE FRAME data may aid in determining conditions present when DTC was set.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
Turn ignition on, with engine off. Observing scan tool, depress accelerator to floor, then slowly release pedal. TP sensor angle value should increase steadily to about 98 percent when pedal is depressed and decrease steadily to about one percent when pedal is released. If TP sensor angle value is as specified, go to next step. If TP sensor angle value is not as specified, go to step 4).
If scan tool display a TP voltage at less than .8 volt when throttle is fully closed, go to next step. If not, go to step 5).
Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. If TP sensor angle value-versus-RPM value is greater than specified value in conditions for setting DTC, go to next step. If TP sensor angle value-versus-RPM value is not greater than the specified value in conditions for setting DTC, go to step 12).
Disconnect TP sensor connector. Observe TP sensor display on scan tool. If TP sensor voltage is less than .5 volt, go to next step. If TP sensor voltage is .5 volt or greater, go to step 7).
Using a test light connected to ground, probe TP sensor battery circuit at harness connector. Connect DVOM between chassis ground and harness connector ground circuit. If DVOM reads greater than .5 volt, go to step 8). If DVOM does not read greater than .5 volt, go to step 9).
Check TP signal circuit for short to voltage. Repair as necessary. After repairs, go to step 16). If circuit is okay, go to step 15).
Check TP sensor ground circuit for high resistance between PCM and TP sensor connectors. Check TP sensor ground circuit for poor connection. Repair as necessary. After repairs, go to step 16). If circuit is okay, go to step 14).
Using DVOM connected to ground, probe 5-volt reference circuit at TP sensor connector. If DVOM reads about 5 volts, go to step 13). If not, go to next step.
Disconnect EGR valve, MAP, A/C and fuel pressure sensor harness connectors. Probe 5-volt reference circuit to TP sensor harness connector. If DVOM reads about 5 volts, go to next step. If not, go to step 12).
Leaving DVOM connected to TP sensor 5-volt reference circuit, reconnect each disconnected component one at a time until voltage reading displays other than 5 volts. Replace component that caused voltage reading to be other than 5 volts. After replacing component, go to step 16).
Check for short to voltage in 5-volt reference circuit. Repair as necessary. After repairs, go to step 16). If circuit is okay, go to step 15).
Replace TP sensor. After replacing sensor, go to step 16).
Check PCM harness connector for poor connection or resistance. Repair as necessary. After repairs, go to step 16). If connection is okay, go to next step.
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start and warm engine to normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0121. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Isuzu Hombre S 1997 - DTC P0122 - TP SENSOR CIRCUIT LOW VOLTAGE

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

Powertrain Control Module (PCM) supplies a 5-volt reference signal and a ground circuit to Throttle Position (TP) sensor, and a signal circuit to monitor throttle angle. TP sensor signal voltage should be about .5 volt at idle and 4.5 volts or greater at wide open throttle.

Isuzu Hombre S 1997 - Condition for setting DTC is follows:

Engine running.
TP sensor reads less than .19 volt for 5 seconds.

Isuzu Hombre S 1997 - Diagnostic Aids

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
Turn ignition on, with engine off (throttle closed). Using scan tool, observe TP sensor voltage. If voltage is less than .2 volt, go to step 4). If voltage is not less than .2 volt, go to next step.
Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. If TP sensor voltage is less than .2 volt, go to next step. If TP sensor voltage is not less than .2 volt, go to step 12).
Disconnect TP sensor connector. Connect a jumper wire between signal circuit and 5-volt reference circuit terminals at TP sensor harness connector. Observe TP sensor voltage. If voltage is greater than 4 volts, go to step 10). If voltage is not greater than 4 volts, go to next step.
Connect a test light between battery voltage and signal circuit terminal at TP sensor harness connector. If voltage is greater than 4 volts, go to next step. If voltage is not greater than 4 volts, go to step 8).
Check 5-volt reference circuit for an open or short to ground. Repair as necessary. After repairs, go to step 12). If circuit is okay, go to next step.
Check 5-volt reference circuit terminal for poor connection at PCM. Repair as necessary. After repairs, go to step 12). If circuit terminal is okay, go to step 11).
Check TP sensor signal circuit for an open or short to ground. Repair as necessary. After repairs, go to step 12). If circuit is okay, go to next step.
Check for poor TP sensor signal circuit terminal connection at PCM. Repair as necessary. After repairs, go to step 12). If circuit is okay, go to step 11).
Replace TP sensor. After replacing sensor, go to step 12).
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start and warm engine to normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0122. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Isuzu Hombre S 1997 - DTC P0123 - TP SENSOR CIRCUIT HIGH VOLTAGE

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

Isuzu Hombre S 1997 - Conditions for setting DTC are as follows:

Engine running.
TP sensor voltage is greater than 3.9 volts for 5 seconds.
MAP less than 60 kPa.
Engine speed less than 1500 RPM.
DTC P0107 and/or P0108 not set. Or
TP sensor voltage is greater than 4.8 volts.
DTCs P0107 or P0108 not set.

Isuzu Hombre S 1997 - Diagnostic Aids

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
Turn ignition on, with engine off (throttle closed). Using scan tool, observe TP sensor voltage. If TP sensor voltage is greater than one volt, go to step 4). If voltage is not greater than one volt, go to next step.
Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. If TP sensor voltage is greater than 3.9 volts, go to next step. If not, go to step 12).
Disconnect TP sensor connector. Observe TP sensor voltage. If voltage is less than .2 volt, go to next step. If voltage is not less than .2 volt, go to step 6).
Connect a test light between battery voltage and sensor ground circuit terminal at TP sensor connector. If test light does not illuminate, go to step 9). If test light illuminates, go to step 7).
Check for short to voltage in signal circuit. Repair as necessary. After repairs, go to step 12). If circuit is okay, go to step 11).
Check for short to voltage in 5-volt reference circuit. Repair as necessary. After repairs, go to step 12). If circuit is okay, go to next step.
Disconnect and inspect TP sensor connector. Repair as necessary. After repairs, go to step 12). If connector is okay, go to step 11).
Check for open in ground circuit. Repair as necessary. After repairs, go to step 12). If circuit is okay, go to step 11).
Replace TP sensor. After replacing sensor, go to step 12).
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start and warm engine to normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0123. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Isuzu Hombre S 1997 - DTC P0125 - ECT EXCESSIVE TIME TO REACH CLOSED LOOP

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

Fuel delivery system will operate in open loop when engine coolant temperature is less than 68?F (20?C). During open loop, PCM ignores oxygen sensor signal and calculates air/fuel ratio based on inputs from Engine Coolant Temperature (ECT) sensor, Throttle Position (TP) sensor and Manifold Absolute Pressure (MAP) sensor.

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

ECT sensor is less than 140?F (60?C) .
IAT sensor is greater than 68?F (20?C) .
Vehicle speed is greater than 5 MPH.
Engine run time is greater than 6 minutes.
System in "open-loop".

Isuzu Hombre S 1997 - Diagnostic Aids

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation. Check and repair wiring as necessary. If wiring is okay, connect a DVOM between signal circuit terminal at ECT sensor harness connector and ground circuit terminal at PCM harness connector. Observe DVOM and bend, wiggle and twist related connectors and wiring harness. If a fault is induced, resistance reading will change.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
Allow engine to cool to ambient temperature. Turn ignition on, with engine off. Using scan tool, compare ECT sensor temperature reading to IAT sensor temperature sensor reading. If readings are close to each other, go to step 4). If readings are not close to each other, go to next step.
Disconnect ECT sensor connector. Using DVOM, check ECT sensor resistance. See ECT TEMPERATURE-TO-RESISTANCE VALUES table. If ECT resistance value is close as indicated, go to step 4). If ECT resistance value is not as specified, go to step 9).
Turn ignition on, with engine off. Disconnect ECT sensor connector. If scan tool indicates ECT sensor temperature is less than -22?F (-30?C), go to next step. If scan tool indicates ECT sensor temperature is -22?F (-30?C) or greater, go to step 8).
Connect a jumper wire between signal circuit and sensor ground circuit terminals at ECT sensor harness connector. If scan tool value is greater than 266?F (130?C), go to next step. If scan tool value is not greater than 266?F (130?C), go to step 7).
Check cooling system for proper operation. Repair as necessary. After repairs, go to step 10). If cooling system is functioning properly, see DIAGNOSTIC AIDS.
Disconnect and inspect ECT sensor and PCM connectors. Repair connectors as necessary. After repairs, go to step 10). If connectors are okay, go to next step.
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to step 10).
Replace ECT sensor. After replacing sensor, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0125. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Isuzu Hombre S 1997 ECT TEMPERATURE-TO-RESISTANCE VALUES

Temperature ?F (?C)	Ohms
212 (100)	177
194 (90)	241
158 (70)	467
122 (50)	973
104 (40)	1459
86 (30)	2238
68 (20)	3520
50 (10)	5670

Isuzu Hombre S 1997 - DTC P0131 - O2S CIRCUIT LOW VOLTAGE SENSOR 1

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

Powertrain Control Module (PCM) supplies about .45 volt to Oxygen Sensor 1 (O2S 1). The O2S 1 varies voltage from about one volt when exhaust is rich to about .10 volt when exhaust is lean. PCM monitors and stores sensor voltage information and evaluates the voltage samples to determine amount of time sensor voltage is out of range. If PCM detects O2S 1 voltage is less than predetermined voltage, DTC will set.

Isuzu Hombre S 1997 - Conditions for setting this DTC:

DTCs P0106, P0107, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0200, P0300, P0301, P0302, P0303, P0304, P0404, P0405, P0506, P0507, P1404, or P1441 not set.
Engine run time is greater than 25 seconds.
Engine coolant temperature is greater than 158?F (70?C) .
Air-fuel ratio between 14.5:1 and 14.7:1.
Engine is in "closed-loop".
TP sensor angle is 5-50 percent. Or
Engine has met above conditions for 20 seconds.
O2S 1 voltage is less than 43 mV for greater than 2 minutes.

Isuzu Hombre S 1997 - Diagnostic Aids

Check oxygen sensor pigtail wire for breaks, contamination or grounding on exhaust manifold. Check for intermittent ground in signal wire between sensor connector and sensor. DO NOT attempt to repair damaged oxygen sensor connector or wiring. If damage is detected, replace oxygen sensor. Check for fuel contamination, improper fuel pressure or exhaust leak, especially near oxygen sensor. Check for vacuum or crankcase leak, causing a lean condition.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
Ensure engine is at normal operating temperature. Turn ignition on, with engine off. Using scan tool, observe O2S 1 voltage. If voltage stays at less than 43 mV, go to next step. If voltage does not stay at less than 43 mV, go to step 7).
Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Using scan tool, observe O2S 1 voltage. If voltage stays at less than 43 mV, go to next step. If voltage does not stay at less than 43 mV, go to step 7).
Turn ignition on, with engine off. Disconnect O2S 1 connector. Observe O2S 1 voltage. If voltage is 407-509 mV, go to step 7). If voltage is not 407-509 mV, go to next step.
Check for short to ground in O2S 1 signal circuit. Repair as necessary. After repairs, go to step 7). If wiring is okay, go to next step.
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0131. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time. See DIAGNOSTIC AIDS.

Isuzu Hombre S 1997 - DTC P0132 - O2S CIRCUIT HIGH VOLTAGE SENSOR 1

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

Engine coolant temperature is greater than 158?F (70?C).
TP sensor angle is 5-50 percent.
Air/fuel ratio is 14.5:1-14.7:1.
Engine is in closed loop.
O2S 1 voltage is greater than 1042 mV for 50 seconds.
O2S 1 voltage is greater than 738 mV in deceleration mode for 50 seconds.

Isuzu Hombre S 1997 - Diagnostic Aids

Check if fuel pressure is too high. PCM can compensate for some increase, however, if fuel pressure is too high, DTC will set. Check for leaking injector(s) or faulty fuel pressure regulator. See appropriate SYSTEM & COMPONENT TESTING article.

Check EVAP system for fuel saturation. Disconnect MAP sensor harness connector and see if rich condition is corrected. If rich condition is corrected, check for faulty MAP sensor. Check for oxygen sensor silicone contamination. Check TP sensor. See appropriate SYSTEM & COMPONENT TESTING article.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
Ensure engine is at normal operating temperature. Turn ignition on, with engine off. Using scan tool, observe O2S 1 sensor voltage. If voltage stays at greater than 1042 mV, go to step 4). If voltage does not stay at greater than 1042 mV, go to next step.
Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Observe O2S 1 sensor voltage. If voltage stays at greater than 1042 mV, go to next step. If voltage does not stay at greater than 1042 mV, go to step 8).
Disconnect O2S 1 connector. Connect a jumper wire between ground and O2S 1 harness connector. Observe O2S 1 voltage. If voltage is less than 350 mV, go to step 7). If voltage is 350 mV or greater, go to next step.
Check for short to ground in O2S 1 signal circuit. Repair as necessary. After repairs, go to step 7). If wiring is okay, go to next step.
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0132. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time. See DIAGNOSTIC AIDS.

Isuzu Hombre S 1997 - DTC P0133 - O2S SLOW RESPONSE SENSOR 1

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

Powertrain Control Module (PCM) continuously monitors Oxygen Sensor 1 (O2S 1) activity for 100 seconds. During the monitor period, PCM counts number of times O2S 1 switches from rich to lean and from lean to rich. PCM then adds amount of time O2S 1 took to complete all switches. With this information, an average time for all switches can be determined. Whenever average time to switch is too slow, a DTC P0133 will set.

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

Average O2S 1 response times are greater than 249 milliseconds for rich to lean or lean to rich sweeps.
Engine speed is 1600-2600 RPM.
TP sensor angle is 8-20 percent.
Ratio of response times is greater than 3.5 or less than .4.
Purge learned memory is greater than 191.
Evaporative emission control system is commanded open for greater than 60 percent Pulse Width Modulated (PWM).

Isuzu Hombre S 1997 - Diagnostic Aids

Check if fuel pressure is too high. PCM can compensate for some increase; however, if fuel pressure is too high, DTC will set. Check for leaking injector(s) or faulty fuel pressure regulator. See appropriate SYSTEM & COMPONENT TESTING article.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
If other DTCs are present, diagnose affected DTC(s). If no other DTCs are present, go to next step.
Start engine. Ensure engine is at normal operating temperature.
Operate vehicle within the conditions required for setting this DTC. Using scan tool, monitor the following:
- LEAN/RICH AVG. (ms).
- RICH/LEAN AVG. (ms).
- RICH/LEAN to LEAN/RICH RATIO SEN. 1 (greater than, less than).
  If average values are less than 249 ms, 249 ms, or ratios greater than 3.5, 0.4, go to next step. If average values are not less than 249 ms, 249 ms, or ratios are not greater than 3.5, 0.4, go to next step.
Inspect the following:
- Check for proper O2S 1 installation.
- Check O2S 1 connector and wiring for corrosion or damage.
- Check O2S 1 ground circuit.
  If a problem is found, go to step 9). If no problems are found, go to next step.
Check exhaust manifold for leaks. Repair as necessary. After repair is completed, repeat step 3). If exhaust is okay, go to next step.
Disconnect O2S 1 connector. Turn ignition on. Using scan tool, monitor O2S 1 voltage. If voltage is 407-509 mV, go to next step. If voltage is not 407-509 mV, go to step 10).
Connect a jumper wire between ground and signal circuit terminal at O2S 1 harness connector. If voltage is less than 200 mV, go to next step. If voltage is 200 mV or greater, go to step 11).
Replace oxygen sensor. Determine cause of sensor contamination, otherwise new sensor will be damaged. After repair is completed, go to step 17).
Repair wiring or terminal as necessary. DO NOT attempt to repair damaged oxygen sensor connector or wiring. If damage is detected, replace oxygen sensor. After repairs, go to step 17).
Repair short to ground in O2S 1 signal circuit. After repairs, go to step 17).
Remove jumper wire. Measure voltage between ground and signal circuit at O2S 1 harness connector. If voltage is greater than 407 mV, go to next step. If voltage is not greater than 407 mV, go to step 13).
Turn ignition off. Reconnect O2S 1 connector. Disconnect PCM connectors. Check resistance between ground and O2S 1 ground circuit terminal at PCM connector. If resistance is less than 5 ohms, go to step 14). If resistance is not less than 5 ohms, repair open in ground circuit. After repairs, go to step 17).
Turn ignition off. Disconnect PCM harness connectors. Check resistance of signal circuit between O2S 1 harness connector and PCM connector. If resistance is less than 5 ohms, go to step 15). If not, repair open in sensor signal circuit. After repairs, go to step 17).
Check O2S 1 ground circuit terminal connection at PCM connector. Repair or replace terminal as necessary. After repairs, go to step 17). If ground circuit terminal is okay, go to step 16).
Check O2S 1 signal circuit terminal connection at PCM connector. Repair or replace terminal as necessary. After repairs, go to step 17). If ground circuit terminal is okay, go to next step.
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0133. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Isuzu Hombre S 1997 - DTC P0134 - O2S INSUFFICIENT ACTIVITY SENSOR 1

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

Powertrain Control Module (PCM) supplies about .45 volt to Oxygen Sensor 1 (O2S 1). The O2S 1 supplies a varying voltage from about one volt when exhaust is rich to about .10 volt when exhaust is lean. PCM monitors and stores sensor voltage information and evaluates the voltage samples to determine amount of time sensor voltage is out of range. If PCM detects O2S 1 voltage remains at or near .45 volt for an extended period, DTC will set.

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

Engine coolant temperature is greater than 158?F (70?C).
Engine run time is greater than 2 minutes.
TP sensor angle is 8-55 percent.
O2S 1 voltage is 407-509 mV.

Isuzu Hombre S 1997 - Diagnostic Aids

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
Ensure engine is at normal operating temperature. Start engine. Increase engine speed to 1200 RPM for 2 minutes. If scan tool indicates closed loop, go to next step. If scan tool does not indicate closed loop, go to step 4).
Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. If scan tool indicates closed loop, go to next step. If scan tool does not indicate closed loop, go to step 12).
Turn ignition on, with engine off. Disconnect O2S 1 connector. Connect a jumper wire between ground and sensor signal circuit terminal at O2S 1 harness connector. If voltage is less than 200 mV, go to next step. If voltage is not less than 200 mV, go to step 6).
Turn ignition off. Inspect O2S 1 harness connector for faulty terminals or poor connection. Repair faulty terminals or poor connection as necessary. After repairs, go to step 12). If connector is okay, go to step 9).
Turn ignition on, with engine off. Disconnect jumper wire. Using DVOM, measure voltage between ground and sensor signal circuit terminal at O2S 1 harness connector. If voltage is greater than 600 mV, go to step 10). If voltage is not greater than 600 mV, go to next step.
If voltage reading in step 6) is less than 300 mV, go to step 11). If voltage reading is not less than 300 mV, go to next step.
Replace PCM. Program PCM using required equipment. After replacing PCM, go to next step.
Replace oxygen sensor. After replacing sensor, go to step 12).
Check O2S 1 ground circuit for open or poor connection at PCM. Repair as necessary. After repairs, go to step 12). If circuit is okay, go to step 8).
Check O2S 1 signal circuit for open or poor connection at PCM. Repair as necessary. After repairs, go to next step. If circuit is okay, go to step 8).
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0134. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Isuzu Hombre S 1997 - DTC P0137 - HO2S CIRCUIT LOW VOLTAGE SENSOR 2

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

The Heated Oxygen Sensor 2 (HO2S 2) located rear of catalytic converter, produces an output signal relative to oxygen storage capacity of catalytic converter. HO2S 2 signal is less active than signal produced by front oxygen sensor.

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

Engine coolant temperature is greater than 104?F (40?C).
Engine run time is greater than 25 seconds.
TP sensor angle is 5-50 percent.
Air/fuel ratio is 14.5:1-14.7:1.
Engine is in "closed loop".
HO2S 2 voltage is less than 43 mV for greater than 2 minutes.

Isuzu Hombre S 1997 - Diagnostic Aids

Inspect exhaust system for leaks. Check oxygen sensor pigtail wire for breaks, contamination or grounding on exhaust manifold. Check for intermittent short to ground in HO2S 2 signal circuit wire. DO NOT attempt to repair damaged oxygen sensor connector or wiring. If damage is detected, replace oxygen sensor.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
Turn ignition on, with engine off. Using scan tool, observe HO2S 2 voltage. If voltage is less than 200 mV, go to step 4). If voltage is not less than 200 mV, go to next step.
Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Using scan tool, observe HO2S 2 voltage. If voltage is less than 40 mV, go to next step. If voltage is not less than 40 mV, go to step 8).
Disconnect HO2S 2 connector. Connect a jumper wire between ground and ground circuit terminal at HO2S harness connector. If voltage is 350-550 mV, go to step 7). If voltage is not 350-550 mV, go to next step.
Turn ignition off. Disconnect PCM connectors. Check HO2S 2 signal circuit for a short to ground or a short to sensor ground circuit. Repair as necessary. After repairs, go to step 8). If circuit is okay, go to next step.
Replace and program replacement PCM. PCM requires special equipment for programming procedures. After replacing PCM, go to step 8).
Replace oxygen sensor. After replacing sensor, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0137. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Isuzu Hombre S 1997 - DTC P0138 - HO2S CIRCUIT HIGH VOLTAGE SENSOR 2

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

The Heated Oxygen Sensor 2 (HO2S 2), located rear of catalytic converter, produces an output signal relative to oxygen storage capacity of catalytic converter. HO2S 2 signal is less active than signal produced by front oxygen sensor.

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

Engine coolant temperature is greater than 158?F (70?C).
Engine run time is greater than 25 seconds.
TP sensor angle is 5-50 percent.
Air/fuel ratio is 14.5:1-14.7:1.
Engine is in "closed-loop".
HO2S 2 voltage is greater than 1042 mV for 50-75 seconds.

Isuzu Hombre S 1997 - Diagnostic Aids

Check oxygen sensor pigtail wire for breaks and contamination. Check for intermittent short to voltage in HO2S 2 ground circuit wire. DO NOT attempt to repair damaged oxygen sensor connector or wiring. If damage is detected, replace oxygen sensor.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
Turn ignition on, with engine off. Using scan tool, observe HO2S 2 voltage. If voltage is greater than 1042 mV, go to step 4). If voltage is not greater than 1042 mV, go to next step.
Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Using scan tool, observe HO2S 2 voltage. If voltage is greater than 1042 mV, go to next step. If voltage is not greater than 1042 mV, go to step 9).
Turn ignition off. Disconnect HO2S 2 connector. Disconnect PCM connectors. Using a DVOM, measure voltage between ground and signal circuit terminal at HO2S 2 harness connector. If voltage is .5 volt or less, go to next step. If voltage is not less than .5 volt, go to step 6).
Reconnect PCM harness connectors. Turn ignition on, with engine off. Connect a jumper wire between ground and sensor ground circuit and signal circuit terminals at HO2S 2 harness connector. If voltage is less than 100 mV, go to step 7). If not, go to step 8).
Repair short to voltage in HO2S 2 signal circuit. After repairs, go to step 9).
Replace oxygen sensor. After replacing sensor, go to step 9).
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0138. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Isuzu Hombre S 1997 - DTC P0140 - HO2S INSUFFICIENT ACTIVITY SENSOR 2

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

Engine coolant temperature is greater than 104?F (40?C).
Engine run time is greater than 30 seconds.
TP sensor angle is 5-50 percent.
Engine is in "closed loop".
HO2S 2 voltage is 425-460 mV for greater than one minute.

Isuzu Hombre S 1997 - Diagnostic Aids

Check oxygen sensor pigtail wire for breaks and contamination. An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation. Check for intermittent open in HO2S 2 signal circuit wire. DO NOT attempt to repair damaged oxygen sensor connector or wiring. If damage is detected, replace oxygen sensor.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
Ensure engine is at normal operating temperature. Start engine. Increase engine speed to 1200 RPM for 2 minutes. Observe HO2S voltage. If voltage is 425-456 mV, go to step 4). If voltage is not 425-456 mV, go to next step.
Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Observe HO2S 2 voltage. If voltage is 425-456 mV, go to next step. If voltage is not 425-456 mV, go to step 11).
Turn ignition on, with engine off. Disconnect HO2S 2 connector. Connect a jumper wire between ground and sensor signal circuit and ground circuit terminals at HO2S 2 harness connector. If voltage is less than 100 mV, go to next step. If voltage is not less than 100 mV, go to step 6).
Turn ignition off. Check for open or poor connection at HO2S 2 harness connector. Repair as necessary. After repairs, go to step 11). If circuit is okay, go to step 7).
Turn ignition off. Remove jumper wire and reconnect HO2S 2 connector. Disconnect PCM connector. Connect a test light between positive battery terminal and sensor ground circuit terminal at PCM harness connector. If test light illuminates, go to step 8). If test light does not illuminate, go to step 9).
Replace oxygen sensor. After replacing sensor, go to step 11).
Check HO2S 2 signal circuit for open or poor connection. Repair circuit as necessary. After repairs, go to step 11). If circuit is okay, go to step 10).
Repair open in HO2S 2 ground circuit. After repairs, go to step 11).
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0140. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Isuzu Hombre S 1997 - DTC P0141 - HO2S HEATER CIRCUIT SENSOR 2

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

Engine coolant temperature is less than 104?F (40?C).
Intake air temperature is less than 104?F (40?C).
TP sensor angle is greater than 20 percent for greater than 4 seconds.
Temperature difference between ECT and IAT sensor is less than 45?F (7?C).
HO2S 2 voltage changes less than 148 mV in 100-190 seconds.

Isuzu Hombre S 1997 - Diagnostic Aids

Check oxygen sensor pigtail wire for breaks and contamination. An intermittent problem can be caused by misrouted harness, rubbed through wire insulation or broken wire inside insulation. DO NOT attempt to repair damaged oxygen sensor connector or wiring. If damage is detected, replace oxygen sensor.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.

NOTE: If engine has been operating, turn ignition off and allow engine to cool down for about 1/2 hour before proceeding.
Turn ignition on, with engine off. Using scan tool, observe HO2S 2 voltage reading. If voltage gradually changes towards zero or one volt, go to step 13). If voltage does not gradually change towards zero or one volt, go to next step.
Disconnect HO2S 2 connector. Connect a test light between ground and ignition feed circuit terminal at HO2S 2 harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 5).
Connect a test light between ground circuit and ignition feed circuit terminals at HO2S 2 harness connector. If test light illuminates, go to step 6). If test light does not illuminate, go to step 7).
Remove and inspect fuse for HO2S 2 ignition feed circuit. If fuse is blown, go to step 8). If fuse is okay, go to step 9).
Inspect HO2S 2 harness connector for faulty terminals or poor connection. Repair terminals as necessary. After repairs, go to step 13). If connector is okay, go to step 10).
Inspect HO2S 2 harness connector for faulty terminals or poor connection. Repair terminals as necessary. After repairs, go to step 13). If connector is okay, go to step 11).
Check for short to ground in HO2S 2 ignition feed circuit. Repair wiring as necessary. After repairs, replace fuse and go to step 13).
Inspect HO2S 2 harness connector for faulty terminals or poor connection. Repair terminals as necessary. After repairs, go to step 13).
Replace oxygen sensor. After replacing sensor, go to next step.
Repair open in ground circuit. After repairs, go to step 13).
Repair open in ignition feed circuit. After repairs, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0141. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Isuzu Hombre S 1997 - DTC P0171 - FUEL TRIM SYSTEM LEAN Circuit Description

PCM monitors oxygen sensor signal voltage and adjusts fuel delivery based on signal voltage. A change made to fuel delivery is indicated by the long and short term fuel trim values. Ideal fuel trim value is about 128 (zero percent).

A fuel trim value of greater than 128 indicates that PCM is adding fuel to compensate for a lean condition. A fuel trim value less than 128 indicates that PCM is reducing amount of fuel to compensate for rich condition. DTC will set if PCM detects an excessively lean condition.

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

IAT -13 to 175?F (-25 to 115?C).
ECT 140-239?F (60-115?C).
Engine speed is 750-3400 RPM.
Vehicle speed is less than 70 MPH.
MAP greater than 27 kPa.
BARO greater than 73.8 kPa.
EVAP purge is not occurring.
Fuel trim index is greater than 160.
Conditions present for longer than 4 seconds.

Isuzu Hombre S 1997 - Diagnostic Aids

If DTC P0171 cannot be duplicated, problem may have been caused by engine running out of fuel. A fuel delivery malfunction will cause DTC to set. Check all items that can cause a lean condition.

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation. DO NOT attempt to repair damaged oxygen sensor connector or wiring. If damage is detected, replace oxygen sensor.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
If any other DTCs are set, diagnose DTCs as necessary before proceeding. If no other DTCs are set, go to next step.
Start and warm engine to normal operating temperature. Ensure system is in closed loop. Using scan tool, select FUEL TRIM INDEX. If fuel trim index is less than 160, go to next step. If fuel trim index is greater than specified, go to step 5).
Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. If fuel trim index is less than 160, go to step 16). If fuel trim index is greater than specification, go to next step.
Check vacuum hoses for splits, kinks and proper routing. Check PCV valve for proper installation. Check for fuel contamination. Check PCM and sensor grounds. Check O2S 1 for correct installation and ensure O2S 1 wiring is not in contact with exhaust manifold. If no problems are found, go to next step. If any problem is found, go to step 7).
Disconnect MAP sensor connector. Operate vehicle in closed loop while monitoring FUEL INDEX TRIM. If fuel trim index is 160 or less, go to step 16). If fuel trim index is 161 or greater, go to step 9).
Repair fault that was detected in step 5). Operate vehicle in "closed-loop" while monitoring FUEL INDEX TRIM. If fuel trim index is less than 165, go to next step. If fuel trim index is greater than 160, go to step 9).
Lean condition is not present at this time. If a driveability problem exists, go to appropriate TROUBLE SHOOTING - NO CODES article. If no driveability problem exist, go to step 16).
Check vacuum hoses for splits, kinks and proper routing. Check throttle body, intake manifold and injector "O" rings for vacuum leaks. Repair as necessary. After repairs, go to step 16). If no repairs are necessary, go to next step.
Start engine and allow it to idle. Using scan tool, check IAC count. If IAC count is greater than 5, go to next step. If IAC count is 5 or less, go to step 12).
Check for fuel contamination. Repair as necessary. After repairs, go to step 16). If fuel is okay, go to step 13).
Go to DTC P0506 or P0507 to check IAC valve performance. Repair as necessary. After repairs, go to step 16). If IAC valve is okay, go to next step.
Connect a fuel pressure gauge to fuel system. Cycle ignition switch 2-3 times. With fuel pump running, observe fuel pressure. If fuel pressure is 41-47 psi (284-325 kPa), go to next step. If fuel pressure is not 41-47 psi (284-325 kPa), repair fuel system as necessary. See appropriate SYSTEM & COMPONENTS TESTING article.
Ensure engine is at normal operating temperature. Start engine and let idle. Observe fuel pressure. Fuel pressure noted in step 13) should drop 3-10 psi (21-69 kPa). If fuel pressure is as specified, perform injector balance test. See FUEL SYSTEM in appropriate SYSTEM & COMPONENT TESTING article. If fuel pressure is not as specified, see BASIC FUEL SYSTEM CHECKS in appropriate BASIC DIAGNOSTIC PROCEDURES article.
Replace MAP sensor. After repair is completed, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0171. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time. See DIAGNOSTIC AIDS.

Isuzu Hombre S 1997 - DTC P0172 - FUEL TRIM SYSTEM RICH Circuit Description

A fuel trim value greater than 128 indicates that PCM is adding fuel to compensate for a lean condition. A fuel trim value less than 128 indicates that PCM is reducing amount of fuel to compensate for rich condition. DTC will set if PCM detects an excessively rich condition.

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

IAT -13 to 175?F (-25 to 115?C).
ECT 140-239?F (60-115?C).
Vehicle speed is less than 70 MPH.
Engine speed is 750-3400 RPM.
Fuel trim index is less than 80.
EVAP purge is not occurring.
Conditions present for 16 seconds.

Isuzu Hombre S 1997 - Diagnostic Aids

Disconnect and inspect PCM connector. Inspect for damaged pins, corrosion and loose wires. Check oxygen sensor wiring harness for intermittent. An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation. DO NOT attempt to repair damaged oxygen sensor connector or wiring. If damage is detected, replace oxygen sensor.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
If any other DTCs are set, diagnose DTCs as necessary before proceeding. If no other DTCs are set, go to next step.
Start and warm engine to normal operating temperature. Ensure system is in closed loop. Using scan tool, select FUEL TRIM INDEX. If fuel trim index is less than 80, go to step 5). If fuel trim index is not less than 80, go to next step.
Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. If fuel trim index is less than 80, go to step 21). If fuel trim index is not less than 80, go to next step.
Turn ignition off. Check air filter. Replace filter as necessary. After repair is completed, go to step 21). If air filter is okay, go to next step.
Check for collapsed or restricted air intake duct. Repair as necessary. After repairs, go to step 21). If air intake duct is okay, go to next step.
Inspect throttle body inlet for damage or foreign objects that may block airflow. Repair as necessary. After repairs, go to step 21). If no repair is necessary, go to next step.
Inspect throttle body bore, throttle plate and IAC passages for carbon build up and foreign objects. Repair as necessary. After repairs, go to step 21). If no repair is necessary, go to next step.
Start engine. Ensure all accessories are off. Note idle condition. If idle is low or unstable, go to next step. If not, go to step 12).
Using scan tool, check IAC count. If IAC count is less than 100, go to step 12). If IAC count is not less than 100, go to next step.
Disconnect MAP sensor connector. Start and warm engine to normal operating temperature. Ensure system is in closed loop. Using scan tool, select FUEL TRIM INDEX display. If fuel trim index is greater than 80, go to step 20). If fuel trim index is not greater than 80, go to next step.
Go to DTC P0506 or P0507 to check IAC valve performance. Repair as necessary. After repairs, go to step 21). If IAC valve is okay, go to next step.
Disconnect fuel pressure regulator vacuum hose. Check vacuum hose for presence of fuel. If fuel is present, replace fuel pressure regulator. After repairs, go to step 21). If fuel pressure regulator is okay, go to next step.
Turn ignition on, with engine off. Using scan tool, monitor THROT POSITION display while slowly depressing accelerator pedal. If reading increases steadily from minimum voltage to maximum voltage at wide open throttle, go to next step. If reading does not increase steadily from minimum voltage to maximum voltage, go to step 19).
Perform BASIC FUEL SYSTEM CHECKS in appropriate BASIC DIAGNOSTIC PROCEDURES article. Repair fuel system as necessary. After repairs, go to step 21) If fuel system is okay, go to next step.
Check fuel evaporation system for proper operation. Ensure canister purge solenoid is functioning properly. See appropriate SYSTEM & COMPONENT TESTING article. Repair as necessary. After repairs, go to step 21). If fuel evaporation system is functioning properly, go to next step.
Perform INJECTOR BALANCE TEST. See FUEL SYSTEM in appropriate SYSTEM & COMPONENT TESTING article. Repair as necessary. After repairs, go to step 21). If no problems are found, go to next step.
Remove and inspect Oxygen Sensor 1 (O2S 1) for silicone contamination. If contamination exists, a powdery White deposit on portion of sensor exposed to exhaust system will be present. If silicone contamination is present, locate and repair source of contamination. Replace O2S 1. After repair is completed, go to step 21). If no contamination exists, see DIAGNOSTIC AIDS.
Check Throttle Position (TP) sensor mounting screws. Tighten or replace screws as necessary. After repair is completed, go to step 21). If mounting screws are okay, replace TP sensor. After replacing sensor, go to step 21).
Replace MAP sensor. After replacing sensor, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0172. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Isuzu Hombre S 1997 - DTC P0200 - INJECTOR CONTROL CIRCUIT

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

Powertrain Control Module (PCM) has 4 injector driver circuits, one for each injector. PCM monitors current in each driver circuit by measuring a voltage drop through a fixed resistor and is able to control it. Current through each driver is allowed to rise to a peak or 4-amps to quickly open injectors. Current is then reduced to one amp to keep injector open. If current cannot reach 4-amps or injector driver is shorted to voltage, DTC P0200 will set.

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

Injector current is less than 4 amps.
Battery voltage is greater than 9 volts.
Conditions met for 5 seconds.

Isuzu Hombre S 1997 - Diagnostic Aids

An injector that is shorted to voltage or is disconnected while engine is operating will cause a DTC P0200 to set. A misfire related DTC should also be set indicating which cylinder is inoperative.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
Attempt to start engine. If engine starts, go to next step. If engine will not start, go to NO START DIAGNOSIS in appropriate BASIC DIAGNOSTIC PROCEDURES article.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow engine to idle for one minute. If DTC P0220 resets, go to step 5). If DTC P0220 does not reset, go to next step.
Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. If DTC P0220 resets, go to next step. If DTC P0220 does not reset, go to step 16).
Turn ignition off. Remove air cleaner outlet resonator. Disconnect all injector connectors. Install an injector test light at No. 1 injector harness connector. Crank engine and observe test light. Check remaining fuel injectors. If test light flashes for all injectors, perform INJECTOR BALANCE TEST. See FUEL SYSTEM in appropriate SYSTEM & COMPONENT TESTING article. If test light does not flash at all injectors, go to next step.
If test light did not flash in step 5) but was on steady, go to next step. If test light did not flash in step 5) and was off, go to step 10).
Disconnect PCM connectors. With test light connected to positive battery terminal, probe affected injector driver circuits. If test light illuminates, go to next step. If test light does not illuminate, go to step 9).
Repair short to ground in injector driver circuit. After repairs, go to step 16).
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to step 16).
With test light connected to ground, probe ignition feed circuit terminal at affected injector harness connector. Crank engine. If test light does not illuminate, go to step 12). If test light illuminates, go to next step.
With test light still connected to ground, probe injector driver circuit terminal at affected injector harness connector. Crank engine. If test light does not illuminate, go to step 13). If test light illuminates, go to step 14).
Repair open in injection feed circuit. After repairs, go to step 16).
Check for open or faulty connection in injector driver circuit. Repair as necessary. After repairs, go to step 16). If circuit is okay, go to step 9).
Repair short to voltage in injector driver circuit. After repairs, go to step 16).
Repair open or faulty connection in injector driver circuit. After repairs, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC which was set. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Isuzu Hombre S 1997 - DTC P0300 - ENGINE MISFIRE DETECTED

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

Powertrain Control Module (PCM) monitors Crankshaft Position (CKP) sensor and Camshaft Position (CMP) sensor to detect if engine is misfiring. PCM looks for a sudden drop in crankshaft speed. This test is executed in blocks of 100 camshaft revolution tests. It may take several tests to set a DTC. Under light misfire conditions, it may take more than one trip to set a DTC. Severe misfire will flash Malfunction Indicator Light (MIL) indicating that catalytic converter damage is possible.

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

Misfire total is 12 counts or more.
Engine speed is 469-6406 RPM.
Battery voltage 9-17 volts.
ECT 20-254?F (-7 to 123?C).
Engine run time longer than 15 seconds.
TP sensor angle has not changed more than 8 percent in one second.

Isuzu Hombre S 1997 - Diagnostic Aids

A intermittent can be caused by a defective CKP sensor reluctor wheel. Remove CKP sensor. Inspect reluctor wheel through CKP sensor mounting hole. Check porosity and condition of reluctor wheel. If reluctor wheel is okay, see TROUBLE SHOOTING - NO CODES article for intermittent diagnosis.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
If DTC P0200 is also set, diagnose that DTC before proceeding. If DTC P0200 is not set, go to next step.
Perform a visual inspection of the following. Check vacuum hoses for splits, kinks and proper routing. Check for leaks at throttle body, intake manifold, EGR valve and PCV system. Check PCM grounds for proper connection. Check injector harness connectors for proper installation. Repair as necessary. After repairs, go to step 32). If no problems are found, go to next step.
Start and allow engine to idle. Using scan tool, select MISFIRE DATA LIST function and monitor MISFIRE CUR. COUNTERS (one counter per cylinder). If any MISFIRE CURRENT counters are incrementing, go to next step. If not, go step 6).
If all counters are equal (within a percentage of each other), go to step 7). If not, go to step 11).
Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. If any of MISFIRE CURRENT counters are incrementing, go to step 5). If MISFIRE CURRENT counters are not incrementing, see DIAGNOSTIC AIDS.
Turn ignition off. Install fuel pressure gauge. Start engine and allow it to idle. If fuel pressure is 41-47 psi (2.9-3.3 kg/cm² ), go to next step. If fuel pressure is not 41-47 psi (2.9-3.3 kg/cm² ), see BASIC FUEL SYSTEM CHECKS in BASIC DIAGNOSTIC PROCEDURES article.
Check for fuel contamination. If fuel is contaminated, go to step 10). If fuel is not contaminated, go to next step.
Check for a basic engine problem (compression, cam timing, throttle body leak, restricted air flow. etc.). Repair as necessary. After repairs, go to step 31).
Replace contaminated fuel. After repair is completed, go to step 31).
Turn ignition off. Disconnect fuel injector harness connector. Temporarily remove ignition coil and Ignition Control Module (ICM) assembly. Install Spark Plug Jumper Wires (J-36012) . Install Spark Tester (J-26792) to spark plug jumper for each cylinder, one at a time. Disconnect spark plug boot from companion cylinder at ignition coil housing and install a jumper wire between ground and spark plug connector at ignition coil housing (1-4 or 2-3). Crank engine and check for spark. If spark is present at all cylinders, go to next step. If spark is not present at one or more cylinders, go to step 20).
Check for faulty spark plugs. Replace defective spark plug(s) as necessary. After repairs, go to step 31). If spark plugs are okay, go to next step.
Turn ignition off. Disconnect fuel injector connectors from injectors. Install an injector test light on injector harness connector for cylinders that had misfired. Crank engine and note test light. If injector test light blinks, go to next step. If injector test light does not blink, go to step 15).
Perform fuel injector test. See SYSTEM & COMPONENT TESTING 9). If injectors are not okay, go to step 16).
Disconnect injector test light. Using a standard test light connected to ground, probe ignition feed of injector harness connector for each affected/misfiring injector. Crank engine. If test light illuminates, go to step 17). If test light does not illuminate, go to step 19).
Replace any faulty fuel injector(s). After replacing injector(s), go to step 31).
Check affected fuel injector driver circuit(s) for an open, short to ground or short to voltage. If problem is found, go to next step. If circuit is okay, go to step 28).
Repair as necessary. After repairs, go to step 31).
Repair open ignition feed circuit between fuel injector harness connector and fuel injector. After repairs, go to step 31).
Remove boot assemblies from affected spark plug cable. Using a DVOM, Check resistance of spark plug cable that did not have a spark. If resistance is less than 30,000 ohms, go to next step. If resistance is not less than 30,000 ohms, go to step 29).
Remove ignition coil from cylinder that did not spark. Check secondary resistance of coil. If resistance is 5000-8000 ohms, go to step 22). If resistance is not 5000-8000 ohms, go to step 30).
Turn ignition off. Disconnect 6-pin Ignition Control Module (ICM) harness connector. Using DVOM connected to ground, probe ignition control cavities. If resistance is 600-2600 ohms, go to next step. If not, go to step 25).
Install a known-good ignition coil. Reconnect ICM harness connector. With spark tester connected to problem cylinder, crank engine and observe spark tester. If spark is present, go to step 30). If spark is not present, go to next step.
Replace ICM module. After replacing module, go to step 31).
Inspect PCM harness connectors. If connectors are okay, go to step 31). If connectors are not okay, go to next step.
Check the ignition control circuit to affected cylinders for an open or short in circuit. Repair as necessary. After repairs, go to step 31). If circuit is okay, go to next step.
Repair or replace connectors. After repairs, go to step 31).
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to step 31).
Replace spark plug cables. After replacing cables, go to step 31).
Replace faulty ignition coil. After replacing ignition coil, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0300. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Isuzu Hombre S 1997 - DTC P0301 - CYLINDER NO. 1 MISFIRE DETECTED

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

Misfire is greater than 12 counts.
Engine speed is 469-6406 RPM.
Battery voltage 9-17 volts.
ECT 20-254?F (-7 to 123?C).
Engine run time is longer than 15 seconds.
TP sensor angle has not changed more than 8 percent in one second.

Isuzu Hombre S 1997 - Diagnostic Aids

An intermittent can be caused by a defective CKP sensor reluctor wheel. Remove CKP sensor. Inspect reluctor wheel through CKP sensor mounting hole. Check porosity and condition of reluctor wheel. If reluctor wheel is okay, see appropriate TROUBLE SHOOTING - NO CODES article for intermittent diagnosis.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
If any other DTCs are set, diagnose DTCs as necessary before proceeding. If no other DTCs are set, go to next step.
Perform a visual inspection of the following. Check vacuum hoses for splits, kinks and proper routing. Check for leaks at throttle body, intake manifold, EGR valve and PCV system. Check PCM grounds for proper connection. Check injector harness connectors for proper installation. Repair as necessary. After repairs, go to step 6). If no problems are found, go to next step.
Start engine and allow it to idle. Using scan tool, select MISFIRE DATA LIST function and monitor MISFIRE CUR. COUNTERS (one counter per cylinder). If MISFIRE CURRENT NO. 1 counter is incrementing, go to next step. If MISFIRE CURRENT NO. 1 counter is not incrementing, go to step 6).
Turn ignition off. Disconnect fuel injector harness connector. Install Spark Tester (J-26792) to cylinder No. 1 spark plug wire. Remove No. 4 spark plug wire from ignition coil. Connect a jumper wire between ground and ignition coil tower (where No. 4 spark plug wire was). Crank engine and check for spark. If spark is present, go to step 8). If spark is not present, go to step 9).
Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. If MISFIRE CURRENT NO. 1 counter is incrementing, go to step 5). If MISFIRE CURRENT NO. 1 counter is not incrementing, go to next step.
If a repair of vacuum hoses was made after visual inspection was performed in step 3), go to step 30). If no problems were found in visual inspection, see DIAGNOSTIC AIDS.
Remove spark plug from No. 1 cylinder. Replace spark plug with a known-good spark plug. Reconnect fuel injection harness connector. Operate vehicle within misfire conditions as recorded in FREEZE FRAME. If MISFIRE CURRENT NO. 1 counter is incrementing, go to step 13). If MISFIRE CURRENT NO. 1 counter is not incrementing, go to step 22).
Remove spark plug wire from No. 1 cylinder. Using DVOM, check plug wire resistance. If resistance is less than 3000 ohms, go to next step. If resistance is not less than 3000 ohms, go to step 23).
Remove ignition coil from cylinder that did not have spark. Check secondary resistance of coil. If resistance is 5000-8000 ohms, go to next step. If resistance is not 5000-8000 ohms, go to step 24).
Replace coil with a known-good coil. Crank engine and check for spark. If spark is present, go to step 24). If spark is not present, go to next step.
Disconnect and inspect Ignition Control Module (ICM) 6-pin connector. Repair as necessary. After repairs, go to step 30). If connector is okay, go to step 25).
Turn ignition off. Disconnect all fuel injector connectors. Install injector test light on injector harness connector for No. 1 cylinder. Crank engine and observe test light. If test light flashes, go to next step. If test light does not flash, go to step 15).
Perform INJECTOR BALANCE TEST. See FUEL SYSTEM in appropriate SYSTEM & COMPONENT TESTING article. If No. 1 injector is okay, go to step 28). If No. 1 injector is not okay, go to step 29).
Remove injector test light. Connect a standard test light between ground and ignition feed terminal at No. 1 injector harness connector. Crank engine and observe test light. If test light is on, go to next step. If test light is off, go to step 27).
Turn ignition off. Disconnect PCM connectors. With test light connected to ground, probe injector driver circuit terminal at No. 1 injector harness connector. If test light is off, go to next step. If test light is on, go to step 26).
With test light connected to positive battery terminal, probe injector No. 1 driver circuit terminal at No. 1 injector harness connector. If test light is off, go to next step. If test light is on, go to step 19).
Inspect PCM connectors for damaged pins, corrosion and loose wires. If connectors are okay, go to step 20). If connectors are not okay, go to step 21).
Repair short to ground in cylinder No. 1 fuel injector driver circuit. After repairs, go to step 30).
Replace PCM. Reprogram replacement PCM. After replacing PCM, go to step 30).
Repair connector or connections as necessary. After repairs, go to step 30).
Replace spark plug. After repairs, go to step 30).
Replace spark plug wire. After repairs, go to step 30).
Replace ignition coil. After repairs, go to step 30).
Replace ICM module. After replacing module, go to step 30).
Repair short to voltage in cylinder No. 1 fuel injector driver circuit. After repairs, go to step 30).
Repair open in ignition feed circuit. After repairs, go to step 30).
Check for a basic engine problem (compression, cam timing, throttle body leak, restricted air flow. etc.). Repair as necessary. After repairs, go to step 30).
Replace defective fuel injector. After replacing fuel injector, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0301. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Isuzu Hombre S 1997 - DTC P0302 - CYLINDER NO. 2 MISFIRE DETECTED

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

Misfire total is greater than 12 counts.
Engine speed is 469-6406 RPM.
Battery voltage is 9-17 volts.
ECT 20-254?F (-7 to 123?C).
Engine run time greater than 15 seconds.
TP sensor angle has not changed more than 8 percent in one second.

Isuzu Hombre S 1997 - Diagnostic Aids

An intermittent can be caused by a defective CKP sensor reluctor wheel. Remove CKP sensor. Inspect reluctor wheel through CKP sensor mounting hole. Check porosity and condition of reluctor wheel. If reluctor wheel is okay, see TROUBLE SHOOTING -NO CODES article for intermittent diagnosis.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
If any other DTCs are set, diagnose DTCs as necessary before proceeding. If no other DTCs are set, go to next step.
Perform a visual inspection of the following. Check vacuum hoses for splits, kinks and proper routing. Check for leaks at throttle body, intake manifold, EGR valve and PCV system. Check PCM grounds for proper connection. Check injector harness connectors for proper installation. Repair as necessary. After repairs, go to step 6). If no problems are found, go to next step.
Start engine and allow it to idle. Using scan tool, select MISFIRE DATA LIST function and monitor MISFIRE CUR. COUNTERS (one counter per cylinder). If MISFIRE CURRENT NO. 2 counter is incrementing, go to next step. If MISFIRE CURRENT NO. 2 counter is not incrementing, go to step 6).
Turn ignition off. Disconnect fuel injector harness connector. Install Spark Tester (J-26792) to cylinder No. 2 spark plug wire. Remove No. 3 spark plug wire from ignition coil. Connect a jumper wire between ground and ignition coil tower (where No. 3 spark plug wire was). Crank engine and check for spark. If spark is present, go to step 8). If spark is not present, go to step 9).
Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. If MISFIRE CURRENT NO. 2 counter is incrementing, go to step 5). If MISFIRE CURRENT NO. 2 counter is not incrementing, go to next step.
If a repair of vacuum hoses was made after visual inspection was performed in step 3), go to step 30). If no problems were found in visual inspection, see DIAGNOSTIC AIDS.
Remove spark plug from No. 2 cylinder. Replace spark plug with a known-good spark plug. Reconnect fuel injection harness connector. Operate vehicle within misfire conditions as recorded in FREEZE FRAME. If MISFIRE CURRENT NO. 2 counter is incrementing properly, go to step 13). If MISFIRE CURRENT NO. 2 counter is not incrementing properly, go to step 22).
Remove spark plug wire from No. 2 cylinder. Using DVOM, check plug wire resistance. If resistance is less than 3000 ohms, go to next step. If resistance is not less than 3000 ohms, go to step 23).
Remove ignition coil from cylinder that did not have spark. Check secondary resistance of coil. If resistance is 5000-8000 ohms, go to next step. If resistance is not 5000-8000 ohms, go to step 24).
Replace coil with a known-good coil. Crank engine and check for spark. If spark is present, go to step 24). If spark is not present, go to next step.
Disconnect and inspect Ignition Control Module (ICM) 6-pin connector. Repair as necessary. After repairs, go to step 30). If connector is okay, go to step 25).
Turn ignition off. Disconnect all fuel injector connectors. Install injector test light on injector harness connector for No. 2 cylinder. Crank engine and observe test light. If test light flashes, go to next step. If test light does not flash, go to step 15).
Perform INJECTOR BALANCE TEST. See FUEL SYSTEM in appropriate SYSTEM & COMPONENT TESTING article. If No. 2 injector is okay, go to step 28). If No. 2 injector is not okay, go to step 29).
Remove injector test light. Connect a test light between ground and ignition feed terminal at No. 2 injector harness connector. Crank engine and observe test light. If test light is on, go to next step. If test light is off, go to step 27).
Turn ignition off. Disconnect PCM connectors. With test light connected to ground, probe injector driver circuit terminal at No. 2 injector harness connector. If test light is off, go to next step. If test light is on, go to step 26).
With test light connected to positive battery terminal, probe injector driver circuit terminal at No. 2 injector harness connector. If test light is off, go to next step. If test light is on, go to step 19).
Inspect PCM connectors for damaged pins, corrosion and loose wires. If connectors are okay, go to step 20). If connectors are not okay, go to step 21).
Repair short to ground in cylinder No. 2 fuel injector driver circuit. After repairs, go to step 30).
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to step 30).
Repair connector or connections as necessary. After repairs, go to step 30).
Replace spark plug. After repairs, go to step 30).
Replace spark plug wire. After repairs, go to step 30).
Replace ignition coil. After repairs, go to step 30).
Replace ICM. After replacing module, go to step 30).
Repair short to voltage in cylinder No. 2 fuel injector driver circuit. After repairs, go to step 30).
Repair open in ignition feed circuit. After repairs, go to step 30).
Check for a basic engine problem (compression, cam timing, throttle body leak, restricted air flow. etc.). Repair as necessary. After repairs, go to step 30).
Replace defective fuel injector. After replacing injector, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0302. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Isuzu Hombre S 1997 - DTC P0303 - CYLINDER NO. 3 MISFIRE DETECTED

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

Misfire total is greater than 12 counts.
Engine speed is 469-6406 RPM.
Battery voltage 9-17 volts.
ECT 20-254?F (-7 to 123?C).
TP sensor angle has not changed more than 8 percent in one second.
Engine run time is more than 15 seconds.

Isuzu Hombre S 1997 - Diagnostic Aids

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
If any other DTCs are set, diagnose DTCs as necessary before proceeding. If no other DTCs are set, go to next step.
Perform a visual inspection of the following. Check vacuum hoses for splits, kinks and proper routing. Check for leaks at throttle body, intake manifold, EGR valve and PCV system. Check PCM grounds for proper connection. Check injector harness connectors for proper installation. Repair as necessary. After repairs, go to step 6). If no problems are found, go to next step.
Start engine and allow it to idle. Using scan tool, select MISFIRE DATA LIST function and monitor MISFIRE CUR. COUNTERS (one counter per cylinder). If MISFIRE CURRENT NO. 3 counter is incrementing, go to next step. If MISFIRE CURRENT NO. 3 counter is not incrementing, go to step 6).
Turn ignition off. Disconnect fuel injector harness connector. Install Spark Tester (J-26792) to cylinder No. 3 spark plug wire. Remove No. 2 spark plug wire from ignition coil. Connect a jumper wire between ground and ignition coil tower (where No. 2 spark plug wire was). Crank engine and check for spark. If spark is present, go to step 8). If spark is not present, go to step 9).
Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. If MISFIRE CURRENT NO. 3 counter is incrementing, go to step 5). If MISFIRE CURRENT NO. 3 counter is not incrementing, go to next step.
If a repair of vacuum hoses was made after visual inspection was performed in step 3), go to step 30). If no problems were found in visual inspection, see DIAGNOSTIC AIDS.
Remove spark plug from No. 3 cylinder. Replace spark plug with a known-good spark plug. Reconnect fuel injection harness connector. Operate vehicle within misfire conditions as recorded in FREEZE FRAME. If MISFIRE CURRENT NO. 3 counter is incrementing properly, go to step 13). If MISFIRE CURRENT NO. 3 counter is not incrementing properly, go to step 22).
Remove spark plug wire from No. 3 cylinder. Using DVOM, check plug wire resistance. If resistance is less than 3000 ohms, go to next step. If resistance is not less than 3000 ohms, go to step 23).
Remove ignition coil from cylinder that did not have spark. Measure secondary resistance of coil. If resistance is not 5000-8000 ohms, go to step 24). If resistance is 5000-8000 ohms, go to next step.
Replace coil with a known-good coil. Crank engine and check for spark. If spark is present, go to step 24). If spark is not present, go to next step.
Disconnect and inspect Ignition Control Module (ICM) 6-pin connector. Repair as necessary. After repairs, go to step 30). If connector is okay, go to step 25).
Turn ignition off. Disconnect all fuel injector connectors. Install injector test light on injector harness connector for No. 3 cylinder. Crank engine and observe test light. If test light flashes, go to next step. If test light does not flash, go to step 15).
Perform INJECTOR BALANCE TEST. See FUEL SYSTEM in appropriate SYSTEM & COMPONENT TESTING article. If No. 3 injector is okay, go to step 28). If No. 3 injector is not okay, go to step 29).
Remove injector test light. Connect a test light between ground and ignition feed terminal at No. 3 injector harness connector. Crank engine and observe test light. If test light is on, go to next step. If test light is off, go to step 27).
Turn ignition off. Disconnect PCM connectors. With test light connected to ground, probe injector driver circuit terminal at No. 3 injector harness connector. If test light is off, go to next step. If test light is on, go to step 26).
With test light connected to positive battery terminal, probe injector driver circuit terminal at No. 3 injector harness connector. If test light is off, go to next step. If test light is on, go to step 19).
Inspect PCM connectors for damaged pins, corrosion and loose wires. If connectors are okay, go to step 20). If connectors are not okay, go to step 21).
Repair short to ground in cylinder No. 3 fuel injector driver circuit. After repairs, go to step 30).
Replace PCM. Program replacement PCM using required equipment. After repairs, go to step 30).
Repair connector or connections as necessary. After repairs, go to step 30).
Replace spark plug. After repair is completed, go to step 30).
Replace spark plug wire. After repair is completed, go to step 30).
Replace ignition coil. After repair is completed, go to step 30).
Replace ICM. After repair is completed, go to step 30).
Repair short to voltage in cylinder No. 3 fuel injector driver circuit. After repair is completed, go to step 30).
Repair open in ignition feed circuit. After repair is completed, go to step 30).
Check for a basic engine problem (cam timing, throttle body leak, restricted air flow. etc.). Repair as necessary. After repair is completed, go to step 30).
Replace defective fuel injector. After repair is completed, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0303. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Isuzu Hombre S 1997 - DTC P0304 - CYLINDER NO. 4 MISFIRE DETECTED

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

Misfire total is greater than 12 counts.
Engine speed is 469-6406 RPM.
Battery voltage 9-17 volts.
ECT 20-254?F (-7 to 123?C).
TP sensor angle has not changed more than 8 percent in one second.
Engine run time is more than 15 seconds.

Isuzu Hombre S 1997 - Diagnostic Aids

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
If any other DTCs are set, diagnose DTCs as necessary before proceeding. If no other DTCs are set, go to next step.
Perform a visual inspection of the following. Check vacuum hoses for splits, kinks and proper routing. Check for leaks at throttle body, intake manifold, EGR valve and PCV system. Check PCM grounds for proper connection. Check injector harness connectors for proper installation. Repair as necessary. After repairs, go to step 6). If no problems are found, go to next step.
Start engine and allow it to idle. Using scan tool, select MISFIRE DATA LIST function and monitor MISFIRE CUR. COUNTERS (one counter per cylinder). If MISFIRE CURRENT NO. 4 counter is incrementing, go to next step. If MISFIRE CURRENT NO. 4 counter is not incrementing, go to step 6).
Turn ignition off. Disconnect fuel injector harness connector. Install Spark Tester (J-26792) to cylinder No. 4 spark plug wire. Remove No. 1 spark plug wire from ignition coil. Connect a jumper wire between ground and ignition coil tower (where No. 1 spark plug wire was). Crank engine and check for spark. If spark is present, go to step 8). If spark is not present, go to step 9).
Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. If MISFIRE CURRENT NO. 4 counter is incrementing, go to step 5). If MISFIRE CURRENT NO. 4 counter is not incrementing, go to next step.
If a repair of vacuum hoses was made after visual inspection was performed in step 3), go to step 30). If no problems were found in visual inspection, see DIAGNOSTIC AIDS.
Remove spark plug from No. 4 cylinder. Replace spark plug with a known-good spark plug. Reconnect fuel injection harness connector. Operate vehicle within misfire conditions as recorded in FREEZE FRAME. If MISFIRE CURRENT NO. 4 counter is incrementing properly, go to step 13). If MISFIRE CURRENT NO. 4 counter is not incrementing properly, go to step 22).
Remove spark plug wire from No. 4 cylinder. Using DVOM, measure plug wire resistance. If resistance is less than 3000 ohms, go to next step. If resistance is not less than 3000 ohms, go to step 23).
Remove ignition coil from cylinder that did not have spark. Measure secondary resistance of coil. If resistance is not 5000-8000 ohms, go to step 24). If resistance is 5000-8000 ohms, go to next step.
Replace coil with a known-good coil. Crank engine and check for spark. If spark is present, go to step 24). If spark is not present, go to next step.
Disconnect and inspect Ignition Control Module (ICM) 6-pin connector. Repair as necessary. After repairs, go to step 30). If connector is okay, go to step 25).
Turn ignition off. Disconnect all fuel injector connectors. Install injector test light on injector harness connector for No. 4 cylinder. Crank engine and observe test light. If test light flashes, go to next step. If test light does not flash, go to step 15).
Perform INJECTOR BALANCE TEST. See FUEL SYSTEM in appropriate SYSTEM & COMPONENT TESTING article. If No. 4 injector is okay, go to step 28). If No. 4 injector is not okay, go to step 29).
Remove injector test light. Connect a test light between ground and ignition feed terminal at No. 4 injector harness connector. Crank engine and observe test light. If test light is on, go to next step. If test light is off, go to step 27).
Turn ignition off. Disconnect PCM connectors. With test light connected to ground, probe injector driver circuit terminal at No. 4 injector harness connector. If test light is off, go to next step. If test light is on, go to step 26).
With test light connected to positive battery terminal, probe injector driver circuit terminal at No. 4 injector harness connector. If test light is off, go to next step. If test light is on, go to step 19).
Inspect PCM connectors for damaged pins, corrosion and loose wires. If connectors are okay, go to step 20). If connectors are not okay, go to step 21).
Repair short to ground in cylinder No. 4 fuel injector driver circuit. After repairs, go to step 30).
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to step 30).
Repair connector or connections as necessary. After repairs, go to step 30).
Replace spark plug. After repairs, go to step 30).
Replace spark plug wire. After repairs, go to step 30).
Replace ignition coil. After repairs, go to step 30).
Replace ICM. After repairs, go to step 30).
Repair short to voltage in cylinder No. 4 fuel injector driver circuit. After repairs, go to step 30).
Repair open in ignition feed circuit. After repairs, go to step 30).
Check for a basic engine problem (cam timing, throttle body leak, restricted air flow. etc.). Repair as necessary. Go to step 30).
Replace defective fuel injector. After repairs, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0304. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Isuzu Hombre S 1997 - DTC P0325 - KNOCK SENSOR CIRCUIT

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

Knock Sensor (KS) is used to detect engine detonation. PCM will retard spark timing based on signals from KS module. The KS produces an AC signal voltage that is sent to the KS module. The amount of AC voltage produced is proportional to the amount of knock.

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

Engine run time is greater than 20 seconds.
ECT is greater than 131?F (56?C).
KS instantaneous voltage is less than one volt.
Engine speed is greater than 2200 RPM.
MAP is greater than 60 kPa.

Isuzu Hombre S 1997 - Diagnostic Aids

Check knock sensor for proper connection. A loose or over-torqued knock sensor can cause DTC to set.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
Start engine. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Operate engine at 10 percent throttle angle. Check Malfunction Indicator Light (MIL). If MIL is on, go to 4). If MIL is off, go to next.
Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. If MIL is on, go to next step. If MIL is off, go to step 15).
While listening to engine, increase and decrease engine RPM. If an audible noise or knock is present, go to next step. If no audible noise or knock is present, go to step 6).
Repair cause of engine noise or knock. After repairs, go to step 15).
Slowly increase engine speed to 2500 RPM. Using scan tool, monitor KS activity. If KS activity increases with engine speed, go to next step. If KS activity does not increase with engine speed, go to step 11).
Check for a poor KS signal circuit terminal connection at PCM connector. Repair as necessary. After repairs, go to step 15). If terminal connection is okay, go to next step.
If KS module has previously been replaced, go to next step. If KS module has not previously been replaced, go to step 10).
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to step 15).
Replace KS module. After replacing module, go to step 15).
Turn ignition off. Disconnect PCM harness connectors. Check resistance between ground and signal circuit terminal at PCM connector. If resistance is 90-110 k/ohms, go to step 7). If resistance is not 90-110 k/ohms, go to next step.
Check KS connector for poor connection. Repair as necessary. After repairs, go to step 15). If connector is okay, go to next step.
Check KS signal circuit for an open, short to ground or short to voltage. Repair as necessary. After repairs, go to step 15). If circuit is okay, go to next step.
Replace KS. After replacing sensor, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0325. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Isuzu Hombre S 1997 - DTC P0335 - CRANKSHAFT POSITION SENSOR CIRCUIT

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

Powertrain Control Module (PCM) supplies battery power and ground to CKP sensor. CKP sensor sends a reference signal to PCM 7 times per revolution to indicate crankshaft position and engine speed. The seventh pulse is the sync pulse and is used for crankshaft position reference. PCM calculates when to pulse ignition coils based on these signals.

Isuzu Hombre S 1997 - Condition for setting this DTC is as follows:

7x resync counter is greater than 15 counts within 4 minutes and 15 seconds.

Isuzu Hombre S 1997 - Diagnostic Aids

If complaint is engine cranks but will not run, DTC P0335 may be set if engine is cranked more than 15 times without turning ignition off between starting attempts.

An intermittent can be caused by a defective CKP sensor reluctor wheel. Remove CKP sensor. Inspect reluctor wheel through CKP sensor mounting hole. Check porosity and condition of reluctor wheel. Intermittent can also be caused by a rubbed through wire insulation or a poor connection.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
If engine will not start, go to no-start diagnosis in BASIC DIAGNOSTIC PROCEDURES article. If engine will start, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle for 5 minutes or until Malfunction Indicator Light (MIL) turns on. If MIL is on, go to next step. If MIL is off, go to step 5).
With engine running, wiggle PCM connectors, CKP sensor connector and related wiring. If engine stumbles, go to step 6). If engine does not stumble, go to step 7).
Operate any non-engine related accessories on vehicle. If MED. RESOLUTION RESYNC CNTR on scan tool resyncs while operating accessories, go to step 9). If MED. RESOLUTION RESYNC CNTR on scan tool does not resync while operating accessories, go to step 4).
Repair poor connector connection, wiring or connector that caused engine to stumble. After repairs, go to step 13).
If MIL turned on in step 3), go to next step. If MIL did not turn on, go to step 13).
Check wiring to PCM, ICM and CKP sensor for pinched or worn through wire insulation. Repair wiring as necessary. After repairs, go to step 13). If wiring is okay, go to step 10).
Repair faulty circuit or accessory component that caused MED. RESOLUTION RESYNC CNTR on scan tool to resync. After repairs, go to step 13).
Replace CKP sensor. Start engine and allow it to idle for 5 minutes or until Malfunction Indicator Light (MIL) turns on. If MIL is on, go to next step. If MIL is off, go to step 13).
Replace PCM. Program replacement PCM using required equipment. Start engine and allow it to idle for 5 minutes or until Malfunction Indicator Light (MIL) turns on. If MIL is on, go to next step. If MIL is off, go to step 13).
Replace ICM. Start engine and allow it to idle for 5 minutes or until Malfunction Indicator Light (MIL) turns on. If MIL is on, go to DIAGNOSTIC AIDS. If MIL is off, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0335. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 3).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Isuzu Hombre S 1997 - DTC P0341 - CAMSHAFT POSITION SENSOR CIRCUIT

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

Powertrain Control Module (PCM) uses CMP sensor signal to determine which cylinder is misfiring when a misfire is present. When PCM receives an intermittent signal from CMP sensor, the CMP RESYNC counter will increment.

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

Engine is running.
CMP RESYNC counter is greater than 15 counts in less than 256 seconds.

Isuzu Hombre S 1997 - Diagnostic Aids

An intermittent problem can be caused by a poor connection, rubbed through wire insulation or broken wire inside insulation. Whenever PCM sees less than 15 resyncs in 256 seconds, counter is reset to zero. If a poor CMP sensor connection is present, CAM SENSOR REFERENCE ACTIVITY counter will stop incrementing and CAM SENSOR RESYNC counter will start incrementing.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
Start engine and allow it to idle. Install scan tool. If CMP RESYNC counter is incrementing, go to next step. If CMP RESYNC counter is not incrementing, go to step 4).
Turn ignition off. Disconnect CMP sensor connector. Turn ignition on. If CMP RESYNC counter is incrementing, go to step 5). If CMP RESYNC counter is not incrementing, go to step 6).
With engine running, carefully wiggle CMP sensor connector. If CMP RESYNC counter is incrementing, go to next step. If CMP RESYNC counter is not incrementing, go to step 8).
Check for poor connection at CMP sensor connector. Repair connector as necessary. After repairs, go to step 9). If connector is okay, go to step 7).
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to step 9).
Replace CMP sensor. After replacing sensor, go to step 9).
Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. If CMP RESYNC counter is incrementing, go to step 3). If CMP RESYNC counter is not incrementing, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0341. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Isuzu Hombre S 1997 - DTC P0342 - CAMSHAFT POSITION SENSOR CIRCUIT LOW

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

Engine is running.
CMP ACTIVITY counter does not increment.

Isuzu Hombre S 1997 - Diagnostic Aids

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
Start engine and allow it to idle. Install scan tool. If CMP ACTIVITY counter is incrementing, go to next step. If CMP ACTIVITY counter is not incrementing, go to step 4).
Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. If CMP ACTIVITY counter is incrementing, go to step 16). If CMP ACTIVITY counter is not incrementing, go to next step.
Disconnect CMP sensor connector. With test light connected to ground, probe CMP feed circuit terminal at CMP sensor harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 6).
With test light connected to positive battery terminal, probe CMP ground circuit terminal at CMP sensor harness connector. If test light illuminates, go to step 7). If test light does not illuminate, go to step 8).
Check for poor connection at CMP feed circuit at PCM connector. Repair as necessary. After repairs, go to step 16). If connection is okay, go to step 15).
Reconnect CMP harness sensor connector. Turn ignition off. Disconnect PCM C2 harness connector. Connect a jumper wire between positive battery terminal and ignition feed circuit terminal at PCM C2 harness connector. With DVOM connected to ground, probe CMP signal circuit terminal at PCM connector. If voltage varies from zero volts to battery voltage, go to step 15). If voltage does not vary from zero volts to battery voltage, go to step 9).
Check for poor connection or open in CMP ground circuit. Repair circuit as necessary. After repairs, go to step 16). If circuit is okay, go to step 15).
If DVOM reading in step 7) is a constant voltage (either zero or battery voltage), go to next step. If voltage reading is not a constant voltage, go to step 11).
Check for a short to voltage in CMP signal circuit. Repair as necessary. After repairs, go to step 16). If circuit is okay, go to step 14).
Disconnect CMP sensor connector. With DVOM connected to positive battery terminal, probe CMP signal circuit terminal at CMP sensor harness connector. If voltage is greater than .5 volt, go to next step. If voltage is not greater than .5 volt, go to step 13).
Repair short to ground in CMP signal circuit. After repairs, go to step 16).
Check for poor connection or an open in CMP signal circuit. Repair as necessary. After repairs, go to step 16). If circuit is okay, go to next step.
Replace CMP sensor. After replacing sensor, go to step 16).
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0342. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Isuzu Hombre S 1997 - DTC P0401 - EGR SYSTEM INSUFFICIENT FLOW

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

A linear Exhaust Gas Recirculation (EGR) valve is used on this system. Powertrain Control Module (PCM) commands EGR valve to operate when necessary by controlling a ground signal through PCM. This can be monitored on a scan tool by selecting DESIRED EGR POSITION function. Ignition voltage is supplied to EGR valve thorough a fuse. PCM monitors results of its command through a feedback signal. Feedback signal is the actual position of the EGR pintle. This feedback signal can also be monitored on a scan tool by selecting ACTUAL EGR POSITION function. The ACTUAL EGR POSITION should always be near the commanded or DESIRED EGR POSITION.

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

Engine speed is 1000-2200 RPM.
Engine speed is 900-1700 RPM (A/T).
Engine coolant temperature is greater than 167?F (75?C).
Barometric Pressure (BARO) is greater than 72 kPa.
Manifold Absolute Pressure (MAP) is 13-32 kPa.
TP angle is less than one percent.
Vehicle speed is greater than 20 MPH.
Decel Exponentially Weighted Moving Average (EWMA) is greater than 2.44 kPa (A/T) or 1.66 kPa (M/T).

Isuzu Hombre S 1997 - Diagnostic Aids

Decel Exponentially Weighted Moving Average (EWMA) value is an average of the difference in expected MAP change and actual MAP change caused by opening EGR valve during deceleration. By driving vehicle to 60 MPH and decelerating to 20 MPH, it can be determined if EGR system is okay, partially restricted or fully restricted.

A negative number; less than -3 indicates system is functioning properly. A positive number indicates system is fully restricted and the expected amount of EGR flow is incorrect. A number that falls between -3 and +2 indicates system is partially restricted. The Decel EWMA value should always be -3 or less. If value becomes more positive, check for damaged EGR pipe, restricted EGR passage or defective EGR valve.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
Start engine and allow it to idle. Using scan tool, command EGR valve to 50 percent. If engine stalls or runs rough, go to step 5). If engine does not stall or run rough, go to next step.
Turn ignition off. Remove EGR valve. Inspect EGR valve, passages and pipe for restriction or damage. Repair as necessary. After repairs, go to step 5). If no problems are found, go to next step.
Replace EGR valve. After repairs, go to next step.
Disconnect negative battery cable for 10 seconds, then reconnect cable. Road test vehicle. Increase vehicle speed to 60 MPH, then release accelerator and allow vehicle to decelerate to 20 MPH. If Decel Exponentially Weighted Moving Average (EWMA) value is not greater than zero, return to step 3). If EWMA is greater than zero, go to next step.

NOTE: For more information on Decel EWMA, see DIAGNOSTIC AIDS.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0401. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Isuzu Hombre S 1997 - DTC P0404 - EGR VALVE PINTLE POSITION OPEN

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

A linear EGR is used to accurately supply exhaust gasses to engine without the use of intake manifold vacuum. EGR is controlled by the PCM using inputs from TP and MAP sensors. PCM monitors the results of its command through a feedback signal. By sending a 5-volt reference and ground to EGR, a voltage signal representing the EGR valve pintle position is sent to PCM. This feedback signal can also be monitored on scan tool and is the actual position of EGR pintle. The actual EGR position should always be near the commanded or desired EGR position.

Isuzu Hombre S 1997 - Conditions for setting DTC:

Ignition voltage is greater than 11.7 volts.
EGR commanded on (desired EGR position is greater than zero percent).
Actual EGR position differs from desired EGR position by greater than 9 percent for 18 seconds.

Isuzu Hombre S 1997 - Diagnostic Aids

Due to moisture in exhaust system, EGR valve may sometimes freeze and stick in colder weather. Problem may disappear after vehicle is brought into a warm shop for repairs. By using scan tool and watching actual EGR and desired EGR positions on a cold engine, fault can be easily verified. Check FREEZE FRAME data to determine if DTC set when vehicle was cold by viewing ECT.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
Turn ignition on, with engine off. Using scan tool, command EGR valve to 25, 50, 75, 100 percent. If actual EGR position follow the desired EGR position, go to step 19). If not, go to next step.
Disconnect EGR harness connector. Using a test light connected to battery voltage, probe EGR valve harness connector ground circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 5).
Connect test light to ground. Probe EGR harness connector control circuit. Using scan tool, command EGR to 25, 50, 75, 100 percent. If test light flash, maintain a steady glow or illuminates and gets brighter as command is raised, go to step 6). If not, go to step 7).
Repair open or poor connection in EGR ground circuit. After repairs, go to step 19).
With test light still connected to ground, probe EGR signal circuit. If test light illuminates, go to step 8). If test light does not illuminate, go to step 9).
With test light still connected to ground, probe EGR control circuit without commanding EGR with scan tool. If test light illuminates, go to step 10). If test light does not illuminate, go to step 11).
Check signal circuit for short to voltage. Repair as necessary. After repairs, go to step 19). If circuit is okay, go to step 12).
Using a DVOM connected to ground, probe 5-volt reference circuit. If voltage reading is about 5 volts, go to step 13). If voltage reading is not about 5 volts, go to step 14).
Check control circuit for short to voltage. Repair as necessary. After repairs, go to step 19). If circuit is okay, go to step 12).
Connect test light to battery voltage and probe EGR control circuit. If test light illuminates, go to step 15). If test light does not illuminate, go to step 16).
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to step 19).
Check EGR ground circuit for poor connection or proper terminal tension at PCM and repair as necessary. After repairs, go to step 19). If circuit is okay, go to step 17).
Check 5-volt reference circuit for short to voltage and repair as necessary. After repair of short, go to step 19). If circuit is okay, go to step 12).
Check control circuit for short to ground. Repair as necessary. After repairs, go to step 19). If circuit is okay, go to step 12).
Check control circuit for an open or poor connection at EGR harness connector. Repair as necessary. After repairs, go to step 19). If circuit is okay, go to step 18).
Replace EGR valve. After replacing EGR, go to step 19).
Check for poor connection at PCM harness connector. Repair as necessary. After repairs, go to next step. If connection is okay, go to step 12).
Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0404. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool did not indicate that this test ran and passed, repeat step 2).
Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

Isuzu Hombre S 1997 - DTC P0405 - EGR VALVE SENSOR SIGNAL LOW

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

Isuzu Hombre S 1997 - Conditions for setting DTC:

Ignition voltage is greater than 11.7 volts.
PCM sees less than 0.11 volt from EGR valve sensor.
Malfunction present for about 25 seconds.

Isuzu Hombre S 1997 - Diagnostic Aids

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
Turn ignition on, with engine off. Using scan tool, command EGR valve to 25, 50, 75, 100 percent. If actual EGR position follow the desired EGR position, go to step 15). If not, go to next step.
Disconnect EGR harness connector. Using DVOM connected to ground, probe EGR valve harness connector 5-volt reference circuit. If DVOM reads about 5 volts, go to next step. If not, go to step 5).
Using a jumper wire, jumper EGR 5-volt reference circuit to signal circuit. If actual EGR position display is 100 percent, go to step 6). If display is not 100 percent, go to step 7).
Using a test light connected to battery voltage, probe EGR 5-volt reference circuit. If test light illuminates, go to step 8). If test light does not illuminate, go to step 9).
Check 5-volt reference and signal circuits for poor connection or proper terminal tension. Repair circuits as necessary. If repairs, go to step 15). If circuits are okay, go to step 10).
Using test light connected to battery voltage, probe EGR signal circuit. If test light illuminates, go to step 11). If test light does not illuminate, go to step 12).
Check for short to ground in EGR 5-volt reference circuit. Repair circuit as necessary. After repairs, go to step 15). If circuit is okay, go to step 13).
Check for open in EGR 5-volt reference circuit. Repair circuit as necessary. After repairing circuit, go to step 15). If circuit is okay, go to step 14).
Replace EGR valve. After replacing EGR, go to step 15).
Check for short to ground in EGR signal circuit. Repair circuit as necessary. After repairing circuit, go to step 15). If circuit is okay, go to step 13).
Check for open in EGR signal circuit. Repair as necessary. After repairs, go to step 15). If circuit is okay, go to step 14).
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to step 15).
Check affected circuit for poor connection or proper terminal tension at PCM. Repair as necessary. After repairs, go to step 15). If circuit is okay, go to step 13).
Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0404. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool did not indicate that this test ran and passed, repeat step 2).
Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

Isuzu Hombre S 1997 - DTC P0420 - TWC SYSTEM LOW EFFICIENCY Circuit Description

A 3-Way catalytic converter is used to maintain low emissions. The PCM monitors exhaust gasses from converter using Heated Oxygen Sensor (HO2S). HO2S is located in exhaust stream past the 3-way catalytic converter. HO2S produces an output signal which indicates the oxygen capacity of the catalyst. This determines the catalyst's ability to convert exhaust emissions effectively.

During normal operation, HO2S signal will be less active than that produced by the front Oxygen Sensor (O2S). Powertrain Control Module (PCM) monitors catalyst efficiency in 2 stages. If catalyst efficiency falls to less than 75 percent, PCM will set a stage one fail flag, but will not illuminate Malfunction Indicator Light (MIL). If catalyst efficiency falls to less than 50 percent, PCM will set a stage 2 fail flag and MIL will be illuminated.

Isuzu Hombre S 1997 - Conditions for setting this DTC are:

Engine speed running for greater than 510 seconds.
BARO greater than 72 kPa.
System in "closed-loop".
Driven for greater than 1200 RPM for longer than 180 seconds. Or with vehicle stopped
Idling at less than 150 RPM from desired idle.
Transmission in Drive (A/T) or Neutral (M/T).
TP angle at zero percent.
ECT greater than 167?F (75?C).
IAT at greater than -4?F (-20?C) but less than 176?F (80?C).
Short term fuel trim is between 103-153.
Catalytic temperature is greater than 644?F (340?C) on 2.2L engines.

Isuzu Hombre S 1997 - Diagnostic Aids

An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
If any other DTCs are set, diagnose DTCs as necessary before proceeding. If no other DTCs are set, go to next step.
Check for exhaust system leak, especially near HO2S. Ensure HO2S connectors are secured and not touching exhaust. If a problem is found, go to next step. If no problem is found, go to step 5).
Repair exhaust system as necessary. After repairs, go to step 6).
Replace catalytic converter. After repairs, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0420. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Isuzu Hombre S 1997 - DTC P0440 - EVAP SYSTEM

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

Evaporative leak detection strategy is based on applying vacuum to EVAP system and monitoring vacuum decay. Powertrain Control Module (PCM) monitors vacuum level by means of fuel tank vacuum sensor input. At a predetermined time, EVAP purge solenoid and EVAP vent solenoid are turned on. This allows engine vacuum to draw a small vacuum on entire EVAP system. Whenever a sufficient vacuum level cannot be achieved, a large leak or faulty EVAP purge solenoid is indicated.

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

BARO greater than 75 kPa.
IAT and ECT are 41-84?F (5-29?C).
IAT is not greater than 2?F (1?C), greater than ECT at start-up.
ECT is not greater than 12?F (7?C), greater than IAT at start-up.
Fuel tank level is 26-74 percent.
EVAP solenoid is enabled.
EVAP system is unable to achieve or maintain vacuum during diagnostic test. Amount of vacuum decay will vary with fuel level.

Isuzu Hombre S 1997 - Diagnostic Aids

Check for the following:

Cranked and punctured EVAP canister.
Damaged or disconnected source vacuum line, EVAP purge line, vent hose, for fuel tank vapor line.
Poor connection at PCM.
Inspect harness connectors for backed out terminals, improper mating, broken lock, damaged terminals, or poor wire connection.
Check for intermittent in circuit.
Check for kinked, pinched or plugged vacuum lines to EVAP purge or fuel tank vapor line. Also check for restrictions.
Faulty or damaged evaporative canister.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
If DTC P0460 is also set, go to that DTC first. If not, go to step 3).
Check fuel cap for missing or loose condition. If problem is found, repair as necessary. After repairs, go to step 20). If repair is not necessary, go to next step.
Turn ignition on, with engine off. Using scan tool, command EVAP canister purge valve and EVAP vent solenoid on and off. If purge valve and vent solenoid click, go to next step. If purge valve and/or vent solenoid do not click, go to PCM OUTPUTS DIAGNOSIS.
Ignition off. Remove fuel filler cap. Ignition on. If fuel tank pressure parameter on scan tool is less than one in. H2O, go to step 8). If not less than one in. H2O, go to next step.
If battery has been disconnected, go to appropriate SYSTEM & COMPONENT TESTING article to diagnose evaporative control system. If not, go to next step.
Disconnect battery cables. After disconnecting battery, go to step 5).
Reinstall fuel cap. Using scan tool, command EVAP vent solenoid on (closed). Zero EVAP pressure and vacuum gauges on EVAP Pressure/Purge Cart (J-41413) . Connect EVAP pressure/purge cart to EVAP service port. Attempt to pressurize EVAP system to 5 in. H2O. Monitor pressure using gauge on EVAP pressure/purge cart. If pressure can be achieved, go to next step. If pressure cannot be achieved, go to step 10).
Maintain EVAP system pressure at 5 in. H2O. Using scan tool, observe FUEL TANK VACUUM PRESSURE. If pressure reading is 3-7 in H2O, go to step 12). If pressure reading is not 3-7 in. H2O, go to step 11).
Disconnect fuel tank vapor and EVAP purge hoses from EVAP canister. Plug canister fitting for fuel tank vapor hose. Ensure EVAP vent solenoid is still commanded on. Connect a hand-held vacuum pump to EVAP purge hose fitting on EVAP canister and apply 5 in. Hg. If vacuum holds, go to step 15). If vacuum does not hold, go to step 14).
Check for restricted fuel tank vapor and EVAP purge hoses. Repair as necessary. After repair is completed, go to step 20). If hoses are okay, check fuel tank pressure sensor. See appropriate SYSTEM & COMPONENT TESTING article. Replace fuel tank pressure sensor or repair related wiring as necessary.
Disconnect vacuum hose at EVAP canister purge valve (from throttle body). Connect a hand-held vacuum pump to EVAP canister purge valve vacuum source fitting. Apply 10 in. Hg. Using scan tool, command EVAP canister purge valve on. If vacuum is released, go to next step. If vacuum holds, go to step 17).
Connect a vacuum gauge to EVAP canister purge valve vacuum hose (from throttle body). Start engine. Increase engine speed to 2500 RPM. If vacuum is greater than 10 in. Hg, see DIAGNOSTIC AIDS. If vacuum is 15 in. Hg or less, go to step 18).
Check for disconnected or damaged vent hose. Also, check for damaged EVAP canister. Repair as necessary. After repair is completed, go to step 20). If no problem is found, go to step 19).
Check for missing or faulty fuel cap. Check for disconnected or leaking fuel tank vapor hose or disconnected or damaged EVAP purge hose. Repair as necessary. After repairs, go to step 20). If no problem is found, go to next step.
Using scan tool, command EVAP vent solenoid on. With EVAP pressure/purge cart connected to EVAP service port, attempt to pressurize EVAP system by leaving cart control knob in PRESSURIZE position. Using Ultrasonic Leak Detector (J-41416) , locate and repair EVAP system leak. It may be necessary to partially lower fuel tank to examine hose connections at top of tank. After repair is completed, go to step 20).
Replace EVAP canister purge valve. After repair is completed, go to step 20).
Locate and repair cause of low or no vacuum. After repair is completed, go to step 20).
Replace EVAP vent solenoid. After repair is completed, go to next step.
Turn ignition on, with engine off. Using scan tool, command EVAP vent solenoid on (closed). Using EVAP pressure/purge cart, pressurize EVAP system to 15 in. H2O. Set rotary switch on pressure/purge cart to HOLD and observe EVAP pressure gauge. If pressure decreases to less than 10 in. H2O within 2 minutes, system is functioning properly. If pressure does not decrease to less than 10 in. H2O within 2 minutes, go to step 3).

Isuzu Hombre S 1997 - DTC P0442 - EVAP SYSTEM SMALL LEAK DETECTED

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

Evaporative leak detection strategy is based on applying vacuum to EVAP system and monitoring vacuum decay. Powertrain Control Module (PCM) monitors vacuum level by means of fuel tank vacuum sensor input. At a predetermined time, EVAP purge solenoid and EVAP vent solenoid are turned on. This allows engine vacuum to draw a small vacuum on entire EVAP system. After desired vacuum level has been achieved, EVAP purge solenoid is turned off, sealing the system. If a small leak is detected, a DTC P0442 will set.

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

BARO is greater than 75 kPa.
ECT and IAT is 41-84?F (5-29?C) at engine start-up.
IAT is not greater than 2?F (1?C) of ECT at engine start-up.
ECT is not greater than 12?F (7?C) of IAT at engine start-up.
Fuel tank level is 26-74 percent.
TP angle is 9-35 percent.
EVAP solenoid is enabled.
EVAP system is unable to achieve or maintain vacuum during diagnostic test. Amount of vacuum decay will vary with fuel level.

Isuzu Hombre S 1997 - Diagnostic Aids

Check for missing or damaged "O" rings at EVAP canister fuel vapor fittings and purge line fittings. Check for cracked EVAP canister. Check for damaged or disconnected vacuum source hose, EVAP purge hose, vent hose or fuel tank vapor hose. Check PCM connector for poor terminal connections. Check for damaged EVAP related wiring harness.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
If DTC P0460 is also set, go to that DTC first. If not, go to next step.
Turn ignition on, with engine off. Using scan tool, command EVAP canister purge valve and EVAP vent solenoid on and off. If purge valve and vent solenoids click, go to next step. If purge valve and/or vent solenoid does not click, see PCM OUTPUTS DIAGNOSIS in DTC P0440.
Remove fuel cap. Using scan tool, observe FUEL TANK VACUUM PRESSURE. If pressure is less than one in. H2O, go to step 7). If pressure is greater than one in. H2O, go to next step.
If battery has been disconnected, check fuel tank pressure sensor. See appropriate SYSTEM & COMPONENT TESTING article. Replace fuel tank pressure sensor or repair related wiring as necessary. If battery has not been disconnected, go to next step.
Disconnect battery cables. After disconnecting battery, go to step 4).
Reinstall fuel cap. Using scan tool, command EVAP vent solenoid on (closed). Zero EVAP pressure and vacuum gauges on EVAP Pressure/Purge Cart (J-41413) . Connect EVAP pressure/purge cart to EVAP service port. Pressurize EVAP system to 5 in. H2O. Monitor pressure using gauge on EVAP pressure/purge cart. If pressure is 3-7 in. H2O, go to next step. If pressure is not 3-7 in. H2O, check fuel tank pressure sensor. See appropriate SYSTEM & COMPONENT TESTING article. Replace fuel tank pressure sensor or repair related wiring as necessary.
Turn ignition on, with engine off. Using scan tool, command EVAP vent solenoid on (closed). Using EVAP pressure/purge cart, pressurize EVAP system to 15 in. H2O. Set rotary switch on pressure/purge cart to HOLD, and observe EVAP pressure gauge. If pressure decreases to less than 10 in. H2O within 2 minutes, go to next step. If pressure does not decrease to less than 10 in. H2O within 2 minutes, see DIAGNOSTIC AIDS.
Disconnect fuel tank vapor and EVAP purge hoses from EVAP canister. Plug canister fitting for fuel tank vapor hose. Connect a vacuum pump to EVAP purge hose fitting on EVAP canister. Ensure EVAP vent solenoid is still commanded on. Apply 5 in. Hg. If vacuum holds, go to step 12). If vacuum does not hold, go to next step.
Check for disconnected or damaged vent hose. Also, check for damaged EVAP canister. Repair as necessary. After repairs, go to step 14). If no problem is found, go to next step.
Replace defective EVAP vent solenoid. After replacing solenoid, go to step 14).
Check for missing or faulty fuel cap. Check for disconnected or leaking fuel tank vapor hose or disconnected or damaged EVAP purge hose. Repair as necessary. After repairs, go to step 14). If no problem is found, go to next step.
Using scan tool, command EVAP vent solenoid on. With EVAP pressure/purge cart connected to EVAP service port, attempt to pressurize EVAP system by leaving cart control knob in PRESSURIZE position. Using Ultrasonic Leak Detector (J-41416) , locate and repair EVAP system leak. It may be necessary to partially lower fuel tank to examine hose connections at top of tank. After repair is completed, go to next step.
Turn ignition on, with engine off. Using scan tool, command EVAP vent solenoid on (closed). Using EVAP pressure/purge cart, pressurize EVAP system to 15 in. H2O. Set rotary switch on pressure/purge cart to HOLD, and observe EVAP pressure gauge. If pressure decreases to less than 10 in. H2O within 2 minutes, system is functioning properly. If pressure does not decrease to less than 10 in. H2O within 2 minutes, repeat step 3).

Isuzu Hombre S 1997 - DTC P0446 - EVAP SYSTEM CANISTER VENT BLOCKED

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

With EVAP vent solenoid open, any vacuum in system should decrease quickly unless vent path is blocked.

Isuzu Hombre S 1997 - Conditions required to test for DTC are:

BARO is greater than 75 kPa.
ECT and IAT sensor temperature is 41-84?F (5-29?C) at engine start-up.
IAT is not greater than 2?F (1?C) of ECT at engine start-up.
ECT is not greater than 12?F (7?C) of IAT at engine start-up.
Fuel tank level is 26-74 percent.
TP angle is 9-35 percent.
EVAP system is unable to achieve or maintain vacuum during diagnostic test. The amount of decay will vary with fuel level.

Isuzu Hombre S 1997 - Diagnostic Aids

Check for kinked, pinched or plugged vent hose between EVAP canister and EVAP vent solenoid. Check PCM connector for poor terminal connections. Check for damaged EVAP related wiring harness.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
If DTC P0460 is also set, go to that DTC first. If not, go to next step.
Turn ignition on, with engine off. Using scan tool, command EVAP canister purge valve and EVAP vent solenoids on and off. If purge valve and vent solenoids click, go to next step. If purge valve and/or vent solenoid do not click, see PCM OUTPUTS DIAGNOSIS in DTC P0440.
Remove fuel cap. Using scan tool, observe FUEL TANK VACUUM PRESSURE. If pressure is less than one in. H2O, go to step 7). If pressure is more than one in. H2O, go to next step.
If battery has been disconnected, check fuel tank pressure sensor. See appropriate SYSTEM & COMPONENT TESTING article. Replace fuel tank pressure sensor or repair related wiring as necessary. If battery has not been disconnected, go to next step.
Disconnect battery cables. Go to step 4).
Reinstall fuel cap. Using scan tool, command EVAP vent solenoid on (closed). Zero EVAP pressure and vacuum gauges on EVAP Pressure/Purge Cart (J-41413) . Connect EVAP pressure/purge cart to EVAP service port. Pressurize system to 5 in. H2O. Monitor pressure using gauge on EVAP pressure/purge cart. If pressure is 3-7 in. H2O, go to next step. If pressure is not 3-7 in. H2O, check fuel tank pressure sensor. See appropriate SYSTEM & COMPONENT TESTING article. Replace fuel tank pressure sensor or repair related wiring as necessary.
Turn ignition on, with engine off. Monitor pressure using gauge on EVAP pressure/purge cart. Maintain pressure at 5 in. H2O. Using scan tool, command EVAP vent solenoid off (open). If pressure drops to zero in. H2O within 5 seconds, see DIAGNOSTIC AIDS. If pressure does not drop to zero, go to next step.
Disconnect fuel tank vent hose (large hose marked AIR) from EVAP canister. Set rotary switch on pressure/purge cart to PURGE. Start vehicle and allow engine to reach normal operating temperature. Using scan tool, command purge solenoid to 100 percent. Increase engine speed to 2500 RPM and observe vacuum gauge for 5 seconds. If vacuum remains less than 30 in. H2O, go to next step. If vacuum does not remain less than 30 in. H2O, go to step 12).
Check for kinked, pinched or blocked EVAP vent hose between EVAP canister and EVAP vent solenoid. Replace hose as necessary. After repair is completed, go to step 13). If vent hose is okay, go to next step.
Replace defective EVAP vent solenoid. After repair is completed, go to step 13).
Replace EVAP canister. After repair is completed, go to next step.
Turn ignition on, with engine off. Using scan tool, command EVAP vent solenoid on (closed). Using EVAP pressure/purge cart, pressurize EVAP system to 5 in. H2O. Set rotary switch on pressure/purge cart to HOLD, and observe EVAP pressure gauge. If pressure decreases to zero in. H2O within 5 seconds, system is functioning properly. If pressure does not decrease to zero in. H2O within 5 seconds, repeat step 3).

Isuzu Hombre S 1997 - DTC P0460 - FUEL LEVEL SENSOR CIRCUIT

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

Powertrain Control Module (PCM) uses fuel level input from instrument panel cluster to calculate expected vapor pressures within fuel system. Vapor pressure varies as fuel level changes.

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

Fuel level has not changed greater than 1.6 percent (4 counts) in 120 miles.

Isuzu Hombre S 1997 - Diagnostic Aids

When DTC P0460 is set and an EVAP system DTC is also set, the EVAP DTC cannot be considered valid until DTC P0460 is repaired and cleared.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
Using scan tool, observe fuel level. If scan tool displays either zero percent or 100 percent, go to next step. If not, see DIAGNOSTIC AIDS.
Turn ignition off. Disconnect fuel buffer module connector. Turn ignition on. Check fuel level using scan tool. If scan tool indicates zero percent, go to next step. If not, go to step 6).
Using a jumper wire, jumper fuel buffer module 5-volt reference circuit to signal circuit. Check scan tool display. If scan tool indicates 100 percent, go to next step. If not, go to step 8).
Using a test light connected to battery voltage, probe fuel buffer module sensor ground. If test light illuminates, diagnose instrument cluster. If test light does not illuminate, go to step 7).
Check fuel buffer module sensor signal circuit for short to voltage. Repair as necessary. After repairs, go to step 12). If circuit is okay, go to step 11).
Check for open or malfunctioning connections on fuel buffer module sensor ground circuit. Repair as necessary. After repairs, go to step 12). If circuit is okay, go to step 11).
With test light connected to battery voltage, probe fuel buffer module sensor signal circuit. If scan tool indicates 100 percent value, go to next step. If not, go to step 10).
Check for open or malfunctioning connections on fuel buffer module sensor 5-volt reference circuit. Repair as necessary. After repairs, go to step 12). If circuit is okay, go to step 11).
Check for open or malfunctioning connections on fuel buffer module sensor signal circuit. Repair circuit as necessary. After repairs, go to step 12). If circuit is okay, go to next step.
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0460. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Isuzu Hombre S 1997 - DTC P0480 - COOLING FAN CIRCUIT

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

The cooling fan is controlled by PCM through the fan relay based on inputs from ECT sensor, IAT sensor, A/C selector switch, A/C refrigerant pressure switch and vehicle speed sensor. PCM controls cooling fan by grounding cooling fan control circuit which turns on cooling fan relay.

The fan relay will be commanded on when ECT reaches 223?F (106?C) or greater, A/C is requested or vehicle speed is less than 38 MPH. Cooling fan relay will also be commanded on regardless of vehicle speed when a DTC is set requesting cooling fan to be on, ECT is 304?F (151?C) or greater, or A/C refrigerant pressure is high. Cooling fan may also be commanded on when engine is not running, on certain conditions.

Isuzu Hombre S 1997 - Conditions for setting DTC:

Battery voltage greater than 9.5 volts.
Cooling fan fault line detects a malfunction for 6 seconds.

Isuzu Hombre S 1997 - Diagnostic Aids

If complaint is an overheating problem, determine if complaint is due to an actual boil-over, temperature light, or if temperature gauge indicated overheating.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
Check cooling system. Ensure coolant level and belt tension are correct. Adjust/repair as necessary. After repairs, go to step 24). If no adjustment or repairs were required, go to next step.
Turn ignition on, with engine off. Using scan tool, check if cooling fan is operating with ECT at less than 209?F (98?C). If cooling fan is off, go to next step. If cooling fan is on, go to step 5).
Command cooling fan relay on. If cooling fan does not operate, go to step 6). If cooling fan operates, go to step 24).
Turn ignition off. Disconnect PCM harness connector. If cooling fan turns off, go to step 23). If cooling fan does not turn off, go to step 7).
Disconnect cooling fan relay harness connector. Using a test light connected to ground, probe battery feed circuits in relay harness connector. If test light illuminates on both terminals, go to step 8). If test light does not illuminate on both terminals, go to step 9).
Disconnect cooling fan relay harness connector. With test light connected to ground, probe battery feed circuit in relay harness connector. If test light illuminates, go to step 10). If test light does not illuminate, go to step 11).
Connect a jumper wire between cooling fan relay battery feed and cooling fan battery feed circuit. If cooling fan operates, go to step 12). If cooling fan does not operate, go to step 13).
Repair open in battery feed circuit. After repairs, go to step 24).
Repair short to voltage in cooling fan battery feed circuit. After repairs, go to step 24).
Connect test light battery voltage and probe cooling fan control circuit. If test light illuminates, go to step 14). If test light does not illuminate, go to step 22).
Connect test one end of light to battery voltage and probe cooling fan control circuit. Using scan tool, command cooling fan on. If test light illuminates, go to step 15). If test light does not illuminate, go to step 16).
With jumper wire still connected, disconnect cooling fan harness connector. Using test light connected to ground, probe cooling fan battery feed circuit. If test light illuminates, go to step 17). If test light does not illuminate, go to step 18).
Repair short to ground in cooling fan control circuit. After repairs, go to step 24).
Check terminals to cooling fan relay. Repair as necessary. After repairs, go to step 24). If terminals are okay, go to step 22).
Check cooling fan control circuit for open or poor connection. Repair as necessary. After repairs, go to step 24). If circuit or connection is okay, go to step 23).
Connect test light to battery voltage and probe cooling fan ground circuit. If test light illuminates, go to step 19). If test light does not illuminate, go to step 20).
Repair open or poor connection in cooling fan ignition feed circuit. After repairs, go to step 24).
Check for poor connections at cooling fan harness connector. Repair as necessary. After repairs, go to step 24). If connections are okay, go to step 21).
Repair open or poor connection in cooling fan ground circuit. After repairs, go to step 24).
Replace cooling fan motor. After replacing cooling and motor, go step 24).
Replace cooling fan relay. After replacing relay, go to step 24).
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Turn ignition on, with engine off. Command cooling fan on. If cooling fan operates, system is okay. If cooling fan does not operate, repeat step 2).

Isuzu Hombre S 1997 - DTC P0502 - VSS CIRCUIT LOW INPUT MANUAL TRANSAXLE

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

Vehicle Speed Sensor (VSS) is a permanent magnet generator that is mounted on transaxle. VSS produces a pulsing voltage whenever vehicle speed is greater than 3 MPH. A/C voltage and number of pulses increases with vehicle speed. Powertrain Control Module (PCM) then supplies VSS signal to instrument cluster for speedometer, odometer, electronic transaxle (if equipped) and cruise control operation.

Isuzu Hombre S 1997 - Conditions for setting DTC:

Vehicle speed is less than 2 MPH.
Engine speed is 1700-3600 RPM.
TP angle 8-20 percent.
Engine vacuum between 38-55 kPa.
Conditions met for 5 seconds.

Isuzu Hombre S 1997 - Diagnostic Aids

Scan tool should indicate vehicle speed whenever drive wheel is turning at greater than 3 MPH. A DTC P0502 can falsely set if engine is "brake torqued" in gear. Disregard code if set while drive wheel is not turning. An intermittent problem can be caused by a poor connection, rubbed through wire insulation or broken wire inside insulation. Thoroughly check VSS circuits.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.

CAUTION: Support lower control arms so drive axles are in normal horizontal position or drive axles will be damaged.
Turn ignition off. Raise and support drive axles. Start engine. With engine at idle, place transmission in gear. Using scan tool, monitor vehicle speed. If displayed vehicle speed is greater than zero MPH, go to next step. If displayed vehicle speed is zero MPH, go to step 4).
Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Using scan tool, monitor vehicle speed. If displayed vehicle speed is greater than zero MPH, go to step 12). If displayed vehicle speed is zero MPH, go to next step.
Disconnect PCM connectors. Connect DVOM between VSS terminals. Rotate drive wheel by hand and note A/C voltage reading. If voltage is .5 volt or greater, go to next step. If voltage is not .5 volt or greater, go to step 7).
Check vehicle calibration code. If calibration is incorrect, go to next step. If calibration is correct, go to step 13).
Install proper or most current calibration code. After entering calibration code, go to step 14).
Ensure ignition is off. Check resistance between VSS terminals. If resistance is greater than 1950 ohms, go to next step. If resistance is not greater than 1950 ohms, go to step 9).
Check for an open in VSS signal circuit. Repair as necessary. After repairs, go to step 14). If circuit is okay, go to step 11).
If resistance reading in step 7) is 1300-1950 ohms, go to next step. If resistance is not 1300-1500 ohms, go to step 11).
Check for short to ground in VSS signal circuit. Also, check if VSS circuits are shorted together. Repair circuits as necessary. After repairs, go to step 14). If circuit is okay, go to next step.
Remove VSS. Check resistance between VSS terminals. If resistance is 1300-1950 ohms, go to step 13). If resistance is not 1300-1950 ohms, go to next step.
Replace VSS. After replacing sensor, go to step 14).
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0502. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Isuzu Hombre S 1997 - DTC P0506 - IAC SYSTEM RPM LOW

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

The Idle Air Control (IAC) valve is controlled by the Powertrain Control Module (PCM). PCM uses the IAC to maintain a desired idle speed, which can vary depending on input to PCM. Scan tool reads IAC valve pintle position in counts. The higher the counts, the more air that is allowed to by-pass the throttle plate.

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

IAC valve counts are greater than 145.
BARO is greater than 72 kPa.
TP angle is less than one percent.
Engine run time is greater than 20 seconds.
Idle speed is greater than 60 RPM less than desired RPM for more than 5 seconds.

Isuzu Hombre S 1997 - Diagnostic Aids

Inspect IAC valve connector for proper connection. Inspect throttle stop screw for signs of tampering. Inspect throttle linkage for signs of binding or excessive wear.

A slow or unstable idle may be caused by one of the following:

Fuel system too rich or too lean.
Foreign material in throttle body bore or in air induction system.
Leaking or restricted intake manifold.
Excessive engine overloading.
Too high a viscosity engine oil.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
Turn ignition on, with engine off. Ensure engine is at normal operating temperature, transmission is in Park or Neutral, parking brake is set and A/C is off. Using scan tool, command IAC valve from 900-2000 RPM. If engine RPM changes smoothly, go to next step. If engine RPM does not change smoothly, go to step 5).
Turn ignition off. Disconnect IAC valve connector. Remove IAC valve. Check resistance IAC windings between IAC valve terminals "A" and "B", and then terminals "C" and "D". If one or both readings are not 40-80 ohms, go to step 13). If each reading is 40-80 ohms, go to next step.
Measure resistance between IAC valve terminals "B" and "C", and then between terminals "A" and "D". If each reading is infinite, go to step 15). If one or both readings are not infinite, go to step 13).
Turn ignition on, with engine off. Disconnect IAC valve connector. With test light connected to ground, probe all 4 terminals at IAC valve harness connector. If test light illuminates on 2 terminals, go to next step. If test light does not illuminate on 2 terminals, go to step 7).
With test light connected to positive battery terminal, probe all 4 terminals at IAC valve harness connector. If test light illuminates on 2 terminals, go to step 8). If test light does not illuminate on 2 terminals, go to step 9).
Check for an open or short to ground in IAC valve low and high circuits. Repair as necessary. After repairs, go to step 15). If circuits are okay, go to step 10).
Start engine and allow it to idle. With test light connected to ground, probe all 4 terminals at IAC valve harness connector. If test light flashes on and off for all 4 terminals, go to step 11). If test light does not flash on and off for all 4 terminals, go to step 12).
Check for an open or short to voltage in IAC valve low and high circuits. Repair as necessary. After repairs, go to step 15). If circuits are okay, go to next step.
Check PCM connector for poor terminal connections. Repair as necessary. After repairs, go to step 15). If connector is okay, go to step 14).
Inspect IAC valve passages. Repair as necessary. After repairs, go to step 15). If IAC passages are okay, go to step 13).
If test light remained on constantly for terminals that did not flash in step 8), go to step 9). If test light did not remain on constantly for terminals that did not flash, go to step 7).
Replace IAC valve. After repair is completed, go to step 15).
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0506. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time. See DIAGNOSTIC AIDS.

Isuzu Hombre S 1997 - DTC P0507 - IAC SYSTEM RPM HIGH

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

IAC valve counts are less than 2 counts.
BARO is greater than 72 kPa.
ECT greater than 104?F (40?C).
Idle speed deviates less than desired RPM by greater than 60 RPM for more than 5 seconds.
TP angle is less than 1 percent.

Isuzu Hombre S 1997 - Diagnostic Aids

Inspect IAC valve connector for proper connection. Check for damaged wiring harness. Check for disconnected, cracked or split vacuum hoses. Check PCV valve for proper installation. Inspect intake manifold for cracks.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
Turn ignition on, with engine off. Ensure engine is at normal operating temperature, transmission is in Park or Neutral, parking brake is set and A/C is off. Using scan tool, command IAC valve from 900-2000 RPM. If engine RPM changes smoothly, go to next step. If engine RPM does not change smoothly, go to step 5).
Turn ignition off. Disconnect IAC valve connector. Remove IAC valve. Measure resistance IAC windings between IAC valve terminals "A" and "B", and then terminals "C" and "D". If each reading is 40-80 ohms, go to next step. If one or both readings are not 40-80 ohms, go to step 13).
Measure resistance between IAC valve terminals "B" and "C", and then between terminals "A" and "D". If each reading is infinite, go to step 15). If one or both readings are not infinite, go to step 13).
Turn ignition on, with engine off. Disconnect IAC valve connector. With test light connected to ground, probe all 4 terminals at IAC valve harness connector. If test light turns on for 2 terminals, go to next step. If test light does not turn on for 2 terminals, go to step 7).
With test light connected to positive battery terminal, probe all 4 terminals at IAC valve harness connector. If test light turns on for 2 terminals, go to step 8). If test light does not turn on for 2 terminals, go to step 9).
Check for an open or short to ground in IAC valve lo and high circuits. Repair as necessary. After repair is completed, go to step 15). If circuits are okay, go to step 10).
Start engine and allow to idle. With test light connected to ground, probe all 4 terminals at IAC valve harness connector. If test light flashes on and off for all 4 terminals, go to step 11). If test light does not flash on and off for all 4 terminals, go to step 12).
Check for an open or short to voltage in IAC valve lo and high circuits. Repair as necessary. After repair is completed, go to step 15). If circuits are okay, go to next step.
Check PCM connector terminals for poor connections. Repair as necessary. After repair is completed, go to step 15). If connector is okay, go to step 14).
Inspect IAC valve passages. Repair as necessary. After repair is completed, go to step 15). If IAC passages are okay, go to step 13).
If test light remained on constantly for terminals that did not flash in step 8), go to step 9). If test light did not remain on constantly for terminals that did not flash, go to step 7).
Replace IAC valve. After repair is completed, go to step 15).
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0507. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time. See DIAGNOSTIC AIDS.

Isuzu Hombre S 1997 - DTC P0530 - A/C REFRIGERANT PRESSURE SENSOR CIRCUIT

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

A/C refrigerant pressure sensor responds to changes in A/C refrigerant high side pressure. Powertrain Control Module (PCM) supplies and monitors 5-volt reference circuit to the pressure sensor. Pressure sensor operating range is 0-450 psi. At zero psi, signal voltage should be about .1 volt. At 450 psi or greater, signal voltage should be about 4.9 volts.

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

A/C pressure sensor signal is greater than 453 psi (4.94 volts) with A/C on.
A/C pressure sensor signal is greater than 363 psi (4.0 volts) with A/C off.
Refrigerant pressure is less than zero psi (0.20 volt), IAT signal is greater than 32?F (0?C) and DTC P0112 or P0113 is not set.
Refrigerant pressure is less than zero psi (0.10 volt), IAT signal is greater than 32?F (0?C) and DTC P0112 or P0113 is set.
Conditions exist for greater than 15 seconds.

Isuzu Hombre S 1997 - Diagnostic Aids

Using FREEZE FRAME data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in the FREEZE FRAME data can be useful in determining how many miles since the DTC set. The FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles the diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. Store FREEZE FRAME and FAILURE RECORDS data for conditions which set code. After performing OBD system check, go to next step.
Turn ignition on, with engine off. Using scan tool, check for MAP or TP sensor DTCs. If DTCs are present, go to appropriate DTC for diagnosis. If DTCs are not present, go to next step.
Scan A/C high side value. If high side value is less than 363 psi (4.0 volts), go to step 4). If not, go to step 5).
Unplug A/C pressure sensor connector. If high side value is now less than 76 psi (1.0 volt), go to step 6). If not, go to step 11).
If A/C high side value is less than zero psi (0.20 volt), go to step 7). If not, go to step 8).
Connect positive DVOM lead to battery voltage. Probe A/C pressure sensor ground circuit with negative DVOM lead. If battery voltage is displayed, go to step 9). If not, go to step 10).
Unplug A/C pressure sensor connector. With DVOM to ground, probe A/C pressure sensor harness 5-volt reference circuit. If DVOM displays about 5 volts, go to step 12). If not, go to step 13).
Start engine. Turn A/C switch to OFF position. If A/C clutch remains engaged, go to step 14). If not, go to step 25).
Replace A/C pressure sensor, and go to step 25).
Repair open or poor connection in pressure sensor ground circuit. After repair, go to step 25).
If voltage displayed on scan tool with pressure sensor connector unplugged is greater than 4-6 volts, go to step 16). If voltage displayed is not greater than specification, go to step 17).
Jumper A/C pressure sensor harness connector 5-volt reference circuit to refrigerant pressure signal circuit. If scan tool pressure sensor high side parameter now displays greater than 421 psi (4.6 volts), go to step 9). If not greater than specification, go to step 18).
Repair open or poor connection in pressure sensor 5-volt reference circuit. After repairs, go to step 25).
Unplug A/C relay. With test light connected to battery voltage, probe A/C relay harness control (driver) circuit terminal. If test light illuminates, go to step 19). If not, go to step 20).
Replace PCM. Prior to replacement, check PCM terminals, connectors and wiring harness for damage. After replacing PCM, go to step 25).
Check for short to voltage on pressure sensor signal circuit. If circuit requires repair, repair as necessary. After repairs, go to step 25). If circuit does not require repair, go to step 15).
Check pressure sensor signal circuit for short to 5-volt reference and repair as necessary. If circuit requires repair, repair as necessary and go to step 25). If circuit does not require repair, go to step 15).
With positive DVOM lead connected to positive battery voltage, probe A/C pressure sensor signal circuit at pressure sensor connector with negative lead. If voltage is greater than 0.5 volt, go to step 21). If voltage is less than 0.5 volt, go to step 22).
Check A/C clutch relay control circuit for a short to ground between PCM and relay connector. If circuit requires repair, repair as necessary and go to step 25). If circuit does not require repair, go to step 15.
If A/C clutch disengaged when relay was removed, go to step 23). If not, go to step 24).
Check for short to ground or short to sensor ground in A/C pressure sensor signal circuit. If circuit requires repair, repair as necessary and go to step 25). If circuit does not require repair, go to step 15).
Check for open in pressure sensor signal circuit. Repair circuit as necessary. After repairing circuit, go to step 25). If circuit is okay, go to step 15).
Replace A/C compressor relay. After replacing compressor, go to next step.
Repair short to battery voltage in A/C compressor clutch ignition feed circuit or faulty A/C compressor clutch. After repairing circuit, go to step 25).
Clear DTCs. Start engine and idle to normal operating temperature. Operate vehicle within conditions which set code. If scan tool indicates this code diagnostic has ran and passed, go to next step. If not ran and passed, go to step 2).
Check for additional codes. If additional codes are set, service as necessary. If not, system is okay, see DIAGNOSTIC AIDS.

Isuzu Hombre S 1997 - DTC P0562 - SYSTEM VOLTAGE LOW

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

Powertrain Control Module (PCM) monitors system voltage on ignition feed circuit terminals to PCM. If voltage is less than calibrated value, DTC will set.

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

System voltage is less than 10 volts.
Engine speed is greater than 1300 RPM.
Fault is present for greater than 4 minutes.

Isuzu Hombre S 1997 - Diagnostic Aids

If DTC sets when an accessory is operated, check for poor connection or excessive current draw.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
Start engine. Increase engine speed to 1400 RPM. Load electrical system (turn on headlights, high blower, etc.). Using scan tool, check ignition voltage. If voltage is less than 10 volts, go to next step. If voltage is 10 volts or greater, go to step 8).
Ensure engine speed is still at 1400 RPM. Using DVOM, check voltage at battery. If voltage is greater than 12 volts, go to next step. If voltage is 12 volts or less, repair charging system as necessary.
Turn ignition off. Disconnect PCM connectors. Turn ignition on, with engine off. Using DVOM, check voltage between ground and ignition feed circuit No. 2 terminal at PCM connector. If voltage is greater than 10 volts, go to next step. If voltage is 10 volts or less, go to step 6).
Check for poor connections at PCM harness connector terminals. Repair as necessary. After repairs, go to step 8). If connector terminals are okay, go to step 7).
Repair poor connection in ignition feed circuit No. 2. After repairs, go to step 8).
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0562. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time. See DIAGNOSTIC AIDS.

Isuzu Hombre S 1997 - DTC P0563 - SYSTEM VOLTAGE HIGH

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

Powertrain Control Module (PCM) monitors system voltage on ignition feed circuit terminals to PCM. If voltage is greater than calibrated value, DTC will set.

Isuzu Hombre S 1997 - Condition for setting this DTC is as follows:

System voltage is greater than 17 volts.

Isuzu Hombre S 1997 - Diagnostic Aids

If DTC sets when an accessory is operated, check for poor connection or excessive current draw.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
Turn all accessories off. Start engine. Increase engine speed to 1400 RPM. Using scan tool, check ignition voltage. If voltage is 17 volts or less, go to step 5). If voltage is greater than 17 volts, go to next step.
Increase engine speed to 2000 RPM. Using DVOM, check voltage at battery. If voltage is less than 17 volts, go to next step. If voltage is 17 volts or greater, repair charging system as necessary.
Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0563. If scan tool indicates TEST RAN AND PASSED, no problem is indicated at this time. See DIAGNOSTIC AIDS. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).

Isuzu Hombre S 1997 - DTC P0601 - PCM MEMORY Circuit Description

An Electronically Erasable Programmable Read Only (EEPROM) is used to contain the program information and calibrations required for engine, transmission and powertrain diagnostics operation. Powertrain Control Module (PCM) uses a value called a checksum for error detection of software. Checksum is a value that is equal to all numbers in software added together. PCM adds all values in the software and if that value does not equal the checksum value, a DTC will set.

Isuzu Hombre S 1997 - Condition for setting this DTC is as follows:

PCM detects more than 3 incorrect checksums.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0601. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Isuzu Hombre S 1997 - DTC P0602 - PCM NOT PROGRAMMED Circuit Description

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
If PCM was just replaced, go to next step. If PCM was not just replaced, go to step 4).
Program replacement PCM using required equipment. If DTC resets, attempt to reprogram PCM again (maximum of 3 times). If DTC still resets, go to next step. If DTC does not reset, go to step 5).
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0602. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Isuzu Hombre S 1997 - DTC P1133 - O2S INSUFFICIENT SWITCHING SENSOR 1

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

Powertrain Control Module (PCM) continuously monitors Oxygen Sensor 1 (O2S 1) activity for 100 seconds. During the monitor period, PCM counts number of times than O2S 1 switches from rich to lean and from lean to rich. If total number of switches is less than calibrated value, a DTC P1133 will set.

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

Number of lean to rich counts is less than 15 or rich to lean counts is less than 10.
Engine speed is 1600-2600 RPM.
TP sensor angle is 8-20 percent.
Purge learn memory is greater than 191.
Evaporative emission control system is commanded open for greater than 50 percent Pulse Width Modulated (PWM).

Isuzu Hombre S 1997 - Diagnostic Aids

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
If other DTCs are present, diagnose affected DTCs. If no other DTCs are present, go to next step.
Start engine. Ensure engine is at normal operating temperature. Operate vehicle within the conditions required for setting this DTC. Using scan tool, monitor LEAN/RICH transition and note number of switches. Also, note number of RICH/LEAN transitions. If LEAN/RICH transitions are less than 15 and RICH/LEAN transitions are less than 10, go to next step. If LEAN/RICH transitions are 15 or greater and RICH/LEAN transitions are 10 or greater, go to step 18).
Inspect the following:
- Check for proper O2S 1 installation.
- Check O2S 1 harness connector and wiring for corrosion or damage.
- Check O2S 1 ground circuit.
Repair as necessary. After repairs, go to step 9). If no problems were found, go to next step.
Check exhaust manifold for leaks. Repair as necessary. After repair is completed, repeat step 3). If exhaust is okay, go to next step.
Disconnect O2S 1 connector. Turn ignition on. Using scan tool, monitor O2S 1 voltage. If voltage is 407-509 mV, go to next step. If voltage is not 407-509 mV, go to step 10).
Connect a jumper wire between ground and signal circuit terminal at O2S 1 harness connector. If voltage is less than 200 mV, go to next step. If voltage is not less than 200 mV, go to step 11).
Replace oxygen sensor. Determine cause of sensor contamination, otherwise new sensor will be damaged. After repairs, go to step 17).
Repair wiring or terminal as necessary. DO NOT attempt to repair damaged oxygen sensor connector or wiring. If damage is detected, replace oxygen sensor. After repairs, go to step 17).
Repair short to ground in O2S 1 signal circuit. After repairs, go to step 17).
Remove jumper wire. Check voltage between ground and signal circuit at O2S 1 harness connector. If voltage is greater than 407 mV, go to next step. If voltage is not greater than 407 mV, go to step 13).
Turn ignition off. Disconnect PCM connectors. Check resistance between ground and O2S 1 ground circuit at PCM connector. If resistance is less than 5 ohms, go to step 14). If resistance is not less than 5 ohms, repair open in ground circuit. After repairs, go to step 17).
Turn ignition off. Disconnect PCM connectors. Check resistance of signal circuit between O2S 1 harness connector and PCM connector. If resistance is less than 5 ohms, go to step 15). If resistance is not less 5 ohms, repair open in sensor signal circuit. After repairs, go to step 17).
Check O2S 1 ground circuit terminal connection at PCM connector. Repair or replace terminal as necessary. After repairs, go to step 17). If ground circuit terminal is okay, go to step 16).
Check O2S 1 signal circuit terminal connection at PCM connector. Repair or replace terminal as necessary. After repairs, go to step 17). If ground circuit terminal is okay, go to next step.
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P1133. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, go to DIAGNOSTIC AIDS.

Isuzu Hombre S 1997 - DTC P1171 - FUEL SYSTEM LEAN DURING ACCELERATION Circuit Description

Powertrain Control Module (PCM) internal circuitry can identify if vehicle fuel system is capable of supplying adequate amounts of fuel during heavy acceleration (power enrichment). When a power enrichment mode of operation is requested, PCM will allow additional fuel to be provided to the engine. If PCM does not detect a rich exhaust, a DTC P1171 will set.

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

O2S 1 voltage is less than 300 mV for 5 seconds.
O2S 1 is operating in closed loop.
Fuel injector BPW is greater than zero.
Fuel delivery system is in power enrichment mode.

Isuzu Hombre S 1997 - Diagnostic Aids

A restricted fuel filter can supply adequate amounts of fuel at idle, but may not be able to supply enough fuel during heavy acceleration. Water or alcohol in fuel may cause low O2S 1 voltage during acceleration. Check for defective or plugged fuel injectors.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
If other DTCs are present, diagnose affected DTC(s). If no other DTCs are present, go to next step.
Check fuel level in tank. Add fuel as necessary. If fuel level was low (almost empty), go to step 5). If fuel level was okay, go to next step.
Start engine. Ensure coolant temperature is 167-203?F (75-95?C). Raise engine speed to 1200 RPM. Using scan tool, observe O2S 1 voltage. Voltage should vary within a range of 100-900 mV. Occasionally voltage should increase by more than 447 mV (during power enrichment mode). If voltage is as specified, go to BASIC FUEL SYSTEM CHECKS in appropriate BASIC DIAGNOSTIC PROCEDURES article. If voltage is not as specified, go to DTC P0134.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P1171. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time. See DIAGNOSTIC AIDS.

Isuzu Hombre S 1997 - DTC P1336 - CKP SYSTEM VARIATION NOT LEARNED

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

The crankshaft position system variation learning feature is used to calculate reference period errors caused by slight tolerance variations in the crankshaft, the crankshaft balancer interrupter rings, and the crankshaft position sensor hall effect switches. The calculated error allows PCM to accurately compensate for reference period variations. The crankshaft position system variation learning feature enhances the ability of the PCM to detect misfire events over a wider range of engine speed and load.

The crankshaft position system variation learning procedure must be performed anytime a change is made to the CKP sensor to crankshaft relationship, or if PCM is replaced or reprogrammed.

DTC P1336 set indicates that the crankshaft position system variation values have not been stored in the PCM and the crankshaft position system variation learn procedure must be performed.

The learn procedure is required after the following service procedures have been performed, regardless of whether or not DTC P1336 is set:

PCM replacement
Engine replacement
Crankshaft balancer replacement
Crankshaft position sensor replacement
Any engine repair(s) which disturbs crankshaft/harmonic balancer to crankshaft position sensor relationship.

Isuzu Hombre S 1997 - Conditions for setting DTC:

Crankshaft position system variation values are not stored in the PCM memory.

Isuzu Hombre S 1997 - Diagnostic Aids

DTC P1336 will only set if PCM has not learned the crankshaft position system variation. PCM only needs to learn this variation once per life cycle of vehicle unless the CKP sensor to crankshaft relationship is disturbed. Removing a part for inspection and then reinstalling the same part is considered a disturbance. A fully warmed up engine is critical to learning the variation correctly. If a valid learn occurs, no other learns can be completed that ignition cycle.

If engine cuts out before the specified learn procedure engine speed or at normal fuel cut-off RPM, the PCM is not in the learn procedure mode. Review crankshaft position system variation learning procedure and re-enable the learn procedure. Verify that scan tool indicates Test In Progress.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
Perform crankshaft position system variation learn position as follows:
- Install scan tool.
- Vehicle in Park or Neutral.
- ECT at 158?F (70?C).
- Engage parking brake.
- Block vehicle drive wheels.
- All accessories off.
- Enable crankshaft position system variation learning procedure with scan tool.
- Raise engine speed to 3920 RPM and release throttle as soon as engine cuts out.
  If scan tool indicates that crankshaft position system variation has been performed, go to step 5). If not, go to next step.
Attempt crankshaft position system variation learning procedures for about 10 times. If crankshaft variation has not been learned, go to next step. If crankshaft variation has been learned, go to step 5).
Check for problem with crank sensor to crankshaft relationship. Repair as necessary. After repairs, go to next step.
Using scan tool, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P1336. Operate vehicle within the conditions for setting this DTC. If scan tool indicates test ran and passed, go to next step. If scan tool does not indicate test ran and passed, repeat step 2).
Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

Isuzu Hombre S 1997 - DTC P1380 - ABS DTC ROUGH ROAD DATA UNUSABLE Circuit Description

PCM detects engine misfire by detecting variations in crankshaft deceleration between firing strokes. For accurate detection of engine misfire, PCM must be able to distinguish between crankshaft deceleration caused by actual misfire or deceleration caused by rough road conditions.

The ABS system can detect if vehicle is on a rough road based on wheel acceleration/deceleration data supplied by the wheel speed sensors. If ABS system detects rough road above a predetermined threshold, this information is sent to the PCM via the serial data (UART). PCM can then take the rough road into account when calculating misfire. Even if the ABS is malfunctioning and cannot detect rough roads, the misfire diagnostic will continue to run. However, if a misfire DTC is set, this additional DTC P1380 will also set indicating that rough road data was not available during the misfire calculation due to ABS system malfunction.

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

Vehicle speed is greater than one MPH.
MAP is less than 99 kPa.
Engine speed is less than 3400 RPM.
An ABS DTC is set.

Isuzu Hombre S 1997 - Diagnostic Aids

Setting of this DTC indicates that a misfire was detected and that the PCM could not determine if fault was a true misfire or due to operating vehicle on a rough surface. A misfire can be a true misfire with or without setting this DTC. Check Electronic Brake Control Module (EBCM) for poor connections at serial data (UART) terminals.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
Turn ignition on, with engine off. Using scan tool, check for ABS DTCs. If any ABS DTCs are set, go to next step. If no ABS DTCs are set, go to step 4).
Repair ABS system as necessary. See appropriate ANTI-LOCK BRAKES article in appropriate MITCHELL manual.
Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. If misfire DTC set, go to next step. If misfire DTC did not set, go to step 9).
If DTC P1380 also set, go to next step. If DTC P1380 did not set, go to step 7).
If ABS DTC is also set, go to step 3). If ABS DTC is not set, go to step 8).
Repair condition causing misfire as necessary. After repairs, go to step 9).
Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P1380. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Isuzu Hombre S 1997 - DTC P1381 - MISFIRE DETECTED - NO EBCM/PCM SERIAL DATA Circuit Description

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

Vehicle speed is greater than one MPH.
MAP is less than 99.7 kPa.
Engine speed is less than 3406 RPM.
PCM received no ABS information for 2.5 seconds.

Isuzu Hombre S 1997 - Diagnostic Aids

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
Turn ignition on, with engine off. Using scan tool, attempt to display ABS data. If ABS data can be displayed, go to next step. If ABS data cannot be displayed, go to step 4).
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. If a misfire DTC set, go to step 5). If a misfire DTC did not set, go to step 9).
Repair condition causing ABS data not to be displayed. See appropriate ANTI-LOCK BRAKES article in appropriate MITCHELL manual. After repairs, go to step 3).
If DTC P1381 also set, go to next step. If DTC P1381 did not set, go to step 7).
If ABS data can be displayed, go to step 8). If ABS data cannot be displayed, go to step 4).
Repair condition causing misfire as necessary. After repair is completed, go to step 9).
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P1381. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Isuzu Hombre S 1997 - DTC P1404 - EGR VALVE CLOSED PINTLE POSITION

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

Ignition voltage greater than 11.7 volts.
EGR commanded off (desired EGR position is 0%).
Actual EGR position is greater than 15% for 20 seconds.

Isuzu Hombre S 1997 - Diagnostic Aids

Moisture in exhaust system may cause EGR valve to freeze or stick in colder weather. After vehicle is brought into a warm shop for repairs, EGR valve warms and the problem goes away. By watching ACTUAL EGR POSITION and DESIRED EGR POSITION on a cold vehicle with a scan tool. View FREEZE FRAME data to determine if DTC set when vehicle was cold by viewing ENGINE COOLANT TEMPERATURE and INTAKE AIR TEMPERATURE.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
Turn ignition on, with engine off. Using scan tool, command EGR valve to 25, 50, 75 and 100 percent. If ACTUAL EGR POSITION follows the DESIRED EGR POSITION, go to step 13). If ACTUAL EGR POSITION does not follow the DESIRED EGR POSITION, go to next step.
Disconnect EGR valve connector. If ACTUAL EGR POSITION is near 100 percent, go to next step. If not, go to step 5).
Check signal circuit for short to voltage. Repair as necessary. After repairs, go to step 13). If circuit is okay, go to step 6).
Using DVOM connected to ground, probe EGR 5-volt reference circuit terminal at harness connector. If voltage is 5 volts, go to step 7). If voltage is not 5 volts, go to step 8).
Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to step 13).
Using a test light connected to ground, probe EGR control circuit. If test light illuminates, go to step 9). If test light does not illuminate, go to step 10).
Check EGR valve 5-volt reference circuit for short to voltage. Repair circuit as necessary. After repairs, go to step 13). If circuit is okay, go to step 6).
Check EGR control circuit for short to voltage. Repair as necessary. After repairs, go to step 13). If circuit is okay, go to step 6).
Check EGR sensor ground circuit for open or poor connection at EGR harness connector. Repair as necessary. After repairs, go to step 13). If circuit is okay, go to step 12).
Replace EGR valve. After replacing EGR, go to step 13).
Check PCM harness connector for poor connection. Repair as necessary. After repairs, go to next step. If connections are okay, go to step 6).
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P1406. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time. See DIAGNOSTIC AIDS.

Isuzu Hombre S 1997 - DTC P1406 - EGR VALVE PINTLE POSITION CIRCUIT

Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
Turn engine on and allow it to idle. Using scan tool, read EGR ACTUAL POS. If scan tool displays zero percent, go to next step. If scan tool does not display zero percent, go to step 10).
Using scan tool, select MISC. TESTS and command EGR duty cycle through 25, 50, 75 and 100 percent positions. Compare scan tool display EGR DESIRED POSITION and EGR ACTUAL POS. If both readings are close, go to next. If readings are not close, go to step 5).
Turn ignition on, engine off. Using scan tool, read and record FAILS RECORD DATA. Operate vehicle within conditions noted in FAILED RECORDS DATA. Read SPECIFIC DTC. If scan tool displays DTC P1406 FAILED THIS IGN, go to next step. If scan tool does not display DTC P1406 FAILED THIS IGN, check for an intermittent problem. See TESTS W/O CODES article.
Disconnect EGR valve harness connector. Connect a DVOM between EGR harness connector control and ignition feed circuits. Using scan tool, command EGR duty cycle to 25, 50, 75 and 100 percent position while observing voltage reading on DVOM. If readings are approximately 3 volts at 25 percent and increases to battery voltage at 100 percent, go to step 16). If voltage does not increase as specified, go to next step.
Turn ignition on. Connect a test light between engine ground and EGR valve harness connector ignition feed circuit. If test light illuminates, go to step 8). If test light does not illuminate, go to next step.
Check EGR valve ignition feed circuit fuse. If fuse is blown, locate and repair short to ground in ignition feed circuit. Retest system. If fuse is okay, go to step 23).
Turn ignition off. Disconnect PCM connectors. Check EGR control circuit for an open. If an open is found, repair as necessary. Retest system. If no open is found, go to next step.
Check for faulty EGR control circuit connection at PCM. If faulty connection is found, repair as necessary. Retest system. If connection is okay, go to step 29).
Disconnect EGR valve harness connector. Using scan tool, read EGR ACTUAL POS. If scan tool displays zero percent, go to step 12). If scan tool does not display zero percent, go to next step.
Turn ignition off. Disconnect PCM connectors. Turn ignition on. Check voltage between engine grounds and EGR pintle position circuit. If voltage is about zero volts, go to step 29). If voltage is not as specified, go to step 26).
Connect a test light between battery voltage terminal and EGR harness connector sensor ground circuit. If test light illuminates, go to step 14). If test light does not illuminate, go to next step.
Check sensor ground circuit for faulty connection at PCM or an open between PCM and EGR valve. If a problem is found, repair as necessary. Retest system. If no problem is found, go to step 29).
Connect a test light between battery voltage terminal and EGR harness connector control circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 26).
Turn ignition off. Disconnect PCM. Turn ignition on. Connect test light between battery voltage terminal and EGR control circuit. If test light illuminates, go to step 27). If test light does not illuminate, go to step 29).
Check voltage between EGR valve harness connector sensor ground and 5-volt reference circuits. If voltage is 5 volts, go to next step. If voltage is not as specified, go to step 22).
Connect test light between battery voltage terminal and EGR valve harness connector pintle position circuit. If test light illuminates, go to step 20). If test light does not illuminate, go to next step.
Connect a jumper wire between EGR valve connector 5-volt reference and pintle position circuits. Using scan tool, read EGR DUTY CYCLE. If scan tool displays 100 percent, go to step 21). If scan tool does not display 100 percent, go to next step.
Turn ignition off. Disconnect PCM connectors. Check pintle position circuit for open or faulty connection at PCM. If a problem is found, repair as necessary. Retest system. If no problem is found, go tostep 29).
Turn ignition off. Disconnect PCM connectors. Connect test light between battery voltage terminal and pintle position circuit. If test light illuminates, go to step 28). If test light does not illuminate, go tostep 29).
Check for faulty connection at EGR valve. If faulty connection is found, repair as necessary. Retest system. If connection is okay, go to step 26).
Check for open or short to ground in EGR 5-volt reference circuit. If a problem is found, repair as necessary. Retest system. If no problem is found, go to step 24).
Locate and repair open ignition feed circuit. Retest system.
Check EGR 5-volt reference circuit for faulty connection at PCM. If faulty connection is found, repair as necessary. Retest system. If connection is okay, go to step 29).
Locate and repair short to voltage in pintle position circuit. Retest system.
Replace EGR valve. Retest system.
Locate and repair short to ground in EGR control circuit. Retest system.
Locate and repair short to ground in pintle position circuit. Retest system.
Replace PCM. Retest system.

Isuzu Hombre S 1997 - DTC P1441 - EVAP SYSTEM FLOW DURING NON-PURGE

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

Evaporative Emission (EVAP) system is checked by applying vacuum to EVAP system and monitoring vacuum decay. Powertrain Control Module (PCM) monitors vacuum level by means of fuel tank vacuum sensor input. At a predetermined time, EVAP purge solenoid and EVAP vent solenoid are turned on. This allows engine vacuum to draw a small vacuum on entire EVAP system.

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

BARO is greater than 75 kPa.
IAT 41-84?F (5-29?C).
ECT 41-84?F (5-29?C) at engine start-up.
IAT is not greater than 2?F (1?C) of ECT at engine start-up.
ECT is not greater than 2?F (1?C) of IAT at engine start-up.
Fuel tank level is 26-74 percent.
TP sensor is 9-35 percent.
EVAP solenoid is at 50 percent PWM within 65 seconds of engine run time.
A continuous purge flow condition is detected during diagnostic test.

Isuzu Hombre S 1997 - Diagnostic Aids

Check for incorrect vacuum hose routing to EVAP canister purge valve. Check PCM connector for poor terminal connections. Check for damaged EVAP related wiring harness.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. After performing OBD system check, go to next step.
Turn ignition on, with engine off. Using scan tool, command EVAP canister purge valve and EVAP vent solenoid on and off. If purge valve and vent solenoid click, go to next step. If purge valve and/or vent solenoid do not click, repair wiring or replace purge valve and/or vent solenoid as necessary.
Remove fuel cap. Using scan tool, observe FUEL TANK VACUUM PRESSURE. If pressure is zero in. H2O, go to next step.
If battery has been disconnected, check fuel tank pressure sensor. See appropriate SYSTEM & COMPONENT TESTING article. Replace fuel tank pressure sensor or repair related wiring as necessary. If battery has not been disconnected, go to next step.
Disconnect battery cables, and go to step 3).
Reinstall fuel cap. Using scan tool, command EVAP VENT SOLENOID ON (closed). Zero EVAP pressure and vacuum gauges on EVAP Pressure/Purge Cart (J-41413) . Connect EVAP pressure/purge cart to EVAP service port. Attempt to pressurize EVAP system to 5 in. H2O. Monitor pressure using gauge on EVAP pressure/purge cart. If pressure can be achieved, go to next step. If pressure cannot be achieved, go to step 8).
Maintain EVAP system pressure at 5 in. H2O. Using scan tool, observe FUEL TANK VACUUM PRESSURE. If pressure reading is 4-6 in. H2O, go to next step. If pressure reading is not 4-6 in. H2O, check fuel tank pressure sensor. See appropriate SYSTEM & COMPONENT TESTING article. Replace fuel tank pressure sensor or repair related wiring as necessary.
Disconnect vacuum hose at EVAP canister purge valve (from throttle body). Connect a vacuum pump to EVAP canister purge valve vacuum source fitting. Apply 15 in. Hg vacuum. Using scan tool, command EVAP canister purge valve on. If vacuum holds, go to next step. If vacuum is released, go to step 10).
Check EVAP canister purge valve vacuum hoses for correct routing. If vacuum hoses are routed incorrectly, go to step 11). If vacuum hoses are routed correctly, see DIAGNOSTIC AIDS. If vacuum hoses are routed correctly, go to step 11).
Replace EVAP canister purge valve. After replacing valve, go to step 12).
Correct vacuum hose routing. After repairs, go to next step.
Start engine. Remove fuel cap. Using scan too, command EVAP vent solenoid on (closed) and EVAP canister vent valve off (zero percent). Reinstall fuel cap. While monitoring FUEL TANK VACUUM PRESSURE on scan tool, raise engine speed to 2500 RPM. If pressure is zero in. H2O, system is functioning properly. If pressure is more than zero in. H2O, repeat step 2).

Isuzu Hombre S 1997 - DTC P1520 - PARK NEUTRAL POSITION (PNP) SWITCH CIRCUIT

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

Powertrain Control Module (PCM) supplies ignition voltage to PNP switch through the signal circuit. PNP switch contacts are closed when transmission is in Park or Neutral and open when transmission is in Drive and Reverse.

Isuzu Hombre S 1997 - Conditions required to test for DTC are:

TP angle is 7-26 percent.
Vehicle speed is greater than 40 MPH.
Engine speed 1600-2800 RPM.
PNP switch shows P/N regardless of range selected.
Conditions present for 27 seconds.

Isuzu Hombre S 1997 - Diagnostic Aids

An IAC which is stopped and cannot respond to the VCM, a throttle stop screw which has been tampered with, or a damaged throttle or linkage could cause this DTC to set. A slow, unstable, or fast idle may be caused by a non-IAC system problem that cannot be overcome by the IAC valve.

If scan tool reads an out of range IAC count of greater than 60 counts when idle is too low and zero when idle is too high, check the following:

Fuel system too lean or rich.
Check throttle body bore for foreign material.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
Shift transmission into Park. If scan tool indicates P/N, go to next step. If scan tool does not indicate P/N, go to step 5).
Shift transmission into Drive. If scan tool indicates R/DL, no fault is indicated at this time. If scan tool does not indicate a value of R/DL, go to next step.
Disconnect PNP switch connector. If scan tool indicates R/DL, go to step 11). If scan tool does not indicate R/DL, go to step 9).
Disconnect PNP switch connector. Connect a fused jumper wire between PNP switch harness connector terminals. If scan tool indicates P/N, go to step 11). If scan tool does not indicate P/N, go to next step.
Connect a fused jumper wire between ground and signal circuit terminal at PNP switch harness connector. If scan tool indicates R/DL, go to next step. If scan tool does not indicate R/DL, go to step 8).
Repair open in PNP switch ground circuit. After open circuit is repaired, go to step 13).
Check for an open or short in PNP switch signal circuit. Repair circuit as necessary. After repairs, go to step 13). If circuit is okay, go to step 12).
Check for a short to ground in PNP switch signal circuit. Repair as necessary. After repairs, go to step 13). If circuit is okay, go to next step.
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to step 13).
Check PNP switch adjustment. Adjust switch as necessary. After repairs, go to step 13). If adjustment is okay, go to next step.
Replace PNP switch. After replacing switch, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P1520. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Isuzu Hombre S 1997 - DTC P1601 - SERIAL COMMUNICATION MALFUNCTION

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

Serial data communication bus consists of 4 components. Powertrain Control Module (PCM), Diagnostic Energy Reserve Module (DERM), Electronic Brake Control Module (EBCM) and electronic Instrument Panel Cluster (IPC). IPC is the master of this network and sends out a message through serial data to other modules. Each module responds back to IPC with updated information. If any module does not respond back to IPC, a DTC is set in each applicable module.

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

PCM does not receive 25 valid responses from IPC.
System voltage is greater than 6.8 volts.
Conditions are met for 10 seconds.

Isuzu Hombre S 1997 - Diagnostic Aids

An intermittent problem can be caused by a poor connection, rubbed through wire insulation or broken wire inside insulation.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
Turn ignition on, with engine off. Install scan tool. If scan tool can communicate with EBCM, go to next step. If scan tool cannot communicate with EBCM, go to step 4).
Check the Class 2 serial data for open in circuit. Repair as necessary. After repairs, go to step 8). If circuit is okay, go to step 5).
Check the Class 2 serial data for a short to ground or to voltage. Repair as necessary. After repairs, go to step 8). If circuit is okay, go to step 6).
Check PCM harness connector for poor connection. Repair connections as necessary. After repairs, go to step 8). If connections are okay, go to step 7).
Turn ignition off. Disconnect PCM harness connector. Turn ignition on. Using scan tool, attempt to communicate with EBCM. If communication is established, go to next step. If not, diagnose instrument cluster assembly.
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC which was set. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Isuzu Hombre S 1997 - DTC P1602 - EBCM/EBTCM SERIAL DATA CIRCUIT

NOTE:

For circuit reference, see WIRING DIAGRAMS article.

Isuzu Hombre S 1997 - Circuit Description

A Class II serial data communications system is used on these vehicles to allow various modules to communicate and share information with each other. Each bit of information has 2 lengths, long or short. This allows vehicle wiring to be reduced and the transmission and reception of multiple signals over a single wire. The messages carried on a Class II serial data streams are also prioritized. If two messages attempt to establish communications on the data line at the same time, the message with a higher priority will continue. The message with a lower priority will wait. If a module cannot respond to the PCM, a DTC will set.

Isuzu Hombre S 1997 - Conditions for setting DTC:

PCM cannot communicate with EBCM.

Isuzu Hombre S 1997 - Diagnostic Aids

An intermittent may be caused by poor connection, rubbed through wire insulation or a wire broken inside the insulation.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
Check if scan tool can communicate with EBCM. If communication is established, go to next step. If not, go to step 4).
Check Class 2 serial data circuit for short, or open connection on serial data circuit. Repair as necessary. After repairs, go to step 8). If circuit is okay, go to step 5).
Check Class 2 serial data circuit for poor connection. Repair as necessary. After repairs, go to step 8). If circuit is okay, go to step 6).
Check PCM connector for poor connection. Repair as necessary. After repairs, go to step 8). If connections are okay, go to step 7).
Turn ignition off. Disconnect PCM harness connector. Turn ignition on. Attempt to communicate with EBCM using scan tool. If scan tool communicates with EBCM, go to next step. If not, diagnose instrument cluster assembly.
Replace PCM. Replacement PCM requires special equipment for programming procedures. After replacing PCM, go to next step.
Using scan tool, clear DTCs. Start and warm engine to normal operating temperature. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this diagnostic ran and passed, go to next step. If not, repeat step 2).
Check if any additional DTCs are set. Diagnose affected DTCs. If DTCs are not set, system is okay.

Isuzu Hombre S 1997 - DTC P1621 - PCM MEMORY PERFORMANCE Circuit Description

PCM is the control center of the fuel injection system. It constantly looks at information from various sensors, and controls the systems that affect vehicle performance. PCM also performs the diagnostic function of the system. If can recognize operational problems, alert the driver through the MIL, and store DTC(s).

Isuzu Hombre S 1997 - Condition for setting DTC:

PCM cannot communicate internally.

Isuzu Hombre S 1997 - Diagnostic Procedures

Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Using scan tool, CLEAR INFO or CLEAR DTCS function to clear DTC. Start and warm engine to normal operating temperature. Operate vehicle within the conditions foe setting DTC. If scan tool indicates that diagnostic has ran and passed, go to next step. If scan tool does not indicate that diagnostic has ran and passed, repeat step 2).
Check if any additional DTC(s) are present. If additional DTCs are present, diagnose affected DTC first. If no other DTCs are present, system is okay.

Isuzu Hombre S 1997 - SUMMARY

If no hard fault codes are present, driveability symptoms exist or intermittent codes exist, proceed to TESTS W/O CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.

Isuzu Hombre S 1997 – 1997 ENGINE PERFORMANCE Self Diagnostics Hombre 2 2L

Isuzu Hombre S 1997 - 1997 ENGINE PERFORMANCE Self-Diagnostics - Hombre - 2.2L

Isuzu Hombre S 1997 - INTRODUCTION

Isuzu Hombre S 1997 - SYSTEM DESCRIPTION

Isuzu Hombre S 1997 - TRIP DETECTION LOGIC

Isuzu Hombre S 1997 - Each test is separated in to four types:

Isuzu Hombre S 1997 - SELF-DIAGNOSTIC SYSTEM HARD FAILURES

Isuzu Hombre S 1997 - INTERMITTENT FAILURES

Isuzu Hombre S 1997 - FREEZE-FRAME DATA

Isuzu Hombre S 1997 - DATA LINK CONNECTOR LOCATION

Isuzu Hombre S 1997 - RETRIEVING CODES

Isuzu Hombre S 1997 - CLEARING CODES

Isuzu Hombre S 1997 - PCM REPROGRAM PROCEDURE

Isuzu Hombre S 1997 - PCM LOCATION

Isuzu Hombre S 1997 - CIRCUIT TESTING

Isuzu Hombre S 1997 - DTC P0106 - MAP SENSOR SYSTEM PERFORMANCE

Isuzu Hombre S 1997 - Circuit Description

Isuzu Hombre S 1997 - Diagnostic Aids

Isuzu Hombre S 1997 - Diagnostic Procedures

Isuzu Hombre S 1997 - DTC P0107 - MAP SENSOR CIRCUIT LOW VOLTAGE

Isuzu Hombre S 1997 - Circuit Description

Isuzu Hombre S 1997 - Conditions required to test for DTC are:

Isuzu Hombre S 1997 - Diagnostic Aids

Isuzu Hombre S 1997 - Diagnostic Procedures

Isuzu Hombre S 1997 - DTC P0108 - MAP SENSOR CIRCUIT HIGH VOLTAGE

Isuzu Hombre S 1997 - Circuit Description

Isuzu Hombre S 1997 - Conditions for setting DTC are:

Isuzu Hombre S 1997 - Diagnostic Aids

Isuzu Hombre S 1997 - Diagnostic Procedures

Isuzu Hombre S 1997 - DTC P0112 - IAT SENSOR CIRCUIT LOW VOLTAGE

Isuzu Hombre S 1997 - Circuit Description

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

Isuzu Hombre S 1997 - Diagnostic Aids

Isuzu Hombre S 1997 - Diagnostic Procedures

Isuzu Hombre S 1997 - IAT TEMPERATURE-TO-RESISTANCE VALUES

Isuzu Hombre S 1997 - DTC P0113 - IAT SENSOR CIRCUIT HIGH VOLTAGE

Isuzu Hombre S 1997 - Circuit Description

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

Isuzu Hombre S 1997 - Diagnostic Aids

Isuzu Hombre S 1997 - Diagnostic Procedures

Isuzu Hombre S 1997 - DTC P0117 - ECT SENSOR CIRCUIT LOW VOLTAGE

Isuzu Hombre S 1997 - Circuit Description

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

Isuzu Hombre S 1997 - Diagnostic Aids

Isuzu Hombre S 1997 - Diagnostic Procedures

Isuzu Hombre S 1997 - DTC P0118 - ECT SENSOR CIRCUIT HIGH VOLTAGE

Isuzu Hombre S 1997 - Circuit Description

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

Isuzu Hombre S 1997 - Diagnostic Aids

Isuzu Hombre S 1997 - Diagnostic Procedures

Isuzu Hombre S 1997 - DTC P0121 - TP SENSOR SYSTEM PERFORMANCE

Isuzu Hombre S 1997 - Circuit Description

Isuzu Hombre S 1997 - Conditions required to test for DTC are:

Isuzu Hombre S 1997 - Diagnostic Aids

Isuzu Hombre S 1997 - Diagnostic Procedures

Isuzu Hombre S 1997 - DTC P0122 - TP SENSOR CIRCUIT LOW VOLTAGE

Isuzu Hombre S 1997 - Circuit Description

Isuzu Hombre S 1997 - Condition for setting DTC is follows:

Isuzu Hombre S 1997 - Diagnostic Aids

Isuzu Hombre S 1997 - Diagnostic Procedures

Isuzu Hombre S 1997 - DTC P0123 - TP SENSOR CIRCUIT HIGH VOLTAGE

Isuzu Hombre S 1997 - Circuit Description

Isuzu Hombre S 1997 - Conditions for setting DTC are as follows:

Isuzu Hombre S 1997 - Diagnostic Aids

Isuzu Hombre S 1997 - Diagnostic Procedures

Isuzu Hombre S 1997 - DTC P0125 - ECT EXCESSIVE TIME TO REACH CLOSED LOOP

Isuzu Hombre S 1997 - Circuit Description

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

Isuzu Hombre S 1997 - Diagnostic Aids

Isuzu Hombre S 1997 - Diagnostic Procedures

Isuzu Hombre S 1997 - DTC P0131 - O2S CIRCUIT LOW VOLTAGE SENSOR 1

Isuzu Hombre S 1997 - Circuit Description

Isuzu Hombre S 1997 - Conditions for setting this DTC:

Isuzu Hombre S 1997 - Diagnostic Aids

Isuzu Hombre S 1997 - Diagnostic Procedures

Isuzu Hombre S 1997 - DTC P0132 - O2S CIRCUIT HIGH VOLTAGE SENSOR 1

Isuzu Hombre S 1997 - Circuit Description

Isuzu Hombre S 1997 - Conditions for setting this DTC are as follows:

Isuzu Hombre S 1997 - Diagnostic Aids

Isuzu Hombre S 1997 - Diagnostic Procedures