Isuzu Rodeo S 1992 - 1992 ENGINE PERFORMANCE Self-Diagnostics - Amigo, Pickup & Rodeo - Fuel Injection - 2.6L

Isuzu Rodeo S 1992 - INTRODUCTION

If no faults were found while performing BASIC TESTING , proceed with self-diagnostics. If no fault codes or only pass codes are present after entering self-diagnostics, proceed to TESTS W/O CODES article in the ENGINE PERFORMANCE Section for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.).

Isuzu Rodeo S 1992 - SELF-DIAGNOSTIC SYSTEM HARD FAILURES

Hard failures cause CHECK ENGINE light 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. If a sensor fails, Electronic Control Module (ECM) 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 Rodeo S 1992 - INTERMITTENT FAILURES

Intermittent failures may cause CHECK ENGINE light to flicker or glow and go out after intermittent fault goes away. However, corresponding trouble code will be retained in Electronic Control Module (ECM) memory. If related fault does not reoccur within a certain time frame, related trouble code will be erased from ECM memory. Intermittent failures may be caused by a sensor, connector or wiring related problems. See INTERMITTENTS in appropriate TESTS W/O CODES article in the ENGINE PERFORMANCE Section.

Isuzu Rodeo S 1992 - RETRIEVING CODES

NOTE:

Codes can also be retrieved using a scan tester. Diagnostic connector may also be referred to as ALDL test lead.

1. Code retrieval starts with DIAGNOSTIC CIRCUIT CHECK. CHECK ENGINE light will come on when ignition is on and engine is not running. When engine is started, CHECK ENGINE light should go off. If light remains on while engine is running, a trouble code is present.
2. If light did not come on with key on and engine off, inspect CHECK ENGINE light circuit before continuing. If CHECK ENGINE light failed to operate, see DIAGNOSTIC CIRCUIT CHECK.
3. To retrieve codes, install jumper wire between ALDL diagnostic leads. See Fig. 1 . Turn ignition on. Count number of flashes from CHECK ENGINE light. See Fig. 2 . A Code 12 is identified by a flash, pause and flash, flash. A long pause will occur. Code 12 will repeat 3 times. Each additional code will flash 3 times starting with lowest number code. Once all codes are displayed, codes will repeat.
4. If system is operating properly (with no codes), a Code 12 should exist with ignition on and engine off. This indicates diagnostic system is capable of storing codes. After codes are retrieved, remove jumper wire from diagnostic leads to exit diagnostic mode.

Fig. 1: Isuzu Rodeo S 1992 - Component Locations - Locating Diagnostic Leads

Fig. 2: Isuzu Rodeo S 1992 - Component Locations - Code Display (Typical)

Isuzu Rodeo S 1992 - CLEARING CODES

1. After repairs are performed, clear ECM memory of all stored codes. To clear memory, turn ignition off and remove fuse No. 3 from instrument panel fuse block. Code can also be cleared by removing 60-amp MAIN fuse, located in engine compartment fuse block.
2. Trouble codes can also be cleared by disconnecting negative battery cable. However, other memory functions (clock, radio, etc.) will require resetting.

Isuzu Rodeo S 1992 - CODE CHARTS READ THIS FIRST

NOTE:

To identify ECM connector terminals, see ECM TERMINAL IDENTIFICATION. To test ECM power supply, go to TEST NO. 1.

Isuzu Rodeo S 1992 - ECM LOCATION

ECM is located near left kick panel on all models.

Isuzu Rodeo S 1992 - TROUBLE CODE DEFINITION

Isuzu Rodeo S 1992 TROUBLE CODE IDENTIFICATION

Code	System Affected	Probable Cause
12	System Normal	System Normal
13	O2 Sensor Circuit	Sensor/Circuit, ECM
14	Coolant Temperature Sensor (Shorted)	Temperature Sensor/Circuit, ECM
15	Coolant Temperature Sensor (Open)	Temperature Sensor/Circuit, ECM
21	Throttle Valve Switch (Idle & Full Throttle)	Switch/Circuit, ECM
22	Starter Signal	Circuit, ECM
23	Power Transistor (Shorted)	Transistor/Circuit, ECM
25	Pressure Regulator VSV	VSV/Circuit, ECM
26	Canister Purge VSV	VSV/Circuit, ECM
27	Canister Purge VSV	VSV/Circuit, ECM
32	EGR System	EGR Valve, Backpressure Transducer, Vacuum Switching Valve
33	Fuel Injector Circuit (Open or Grounded)	Wiring, Dropping Resistor, ECM
34	EGR Temperature Sensor	Sensor/Circuit, ECM
35	Power Transistor (Open)	Transistor/Circuit, ECM
41	Crank Angle Sensor	Sensor/Circuit, ECM
43	Throttle Valve Switch (Idle Position)	Switch/Circuit, ECM
44	O2 Sensor (Lean/Rich)	Injectors, Fuel Pressure, Airflow Sensor, O2 Sensor Circuit, Coolant Temperature Sensor, ECM
45	O2 Sensor (Lean/Rich)	Injectors, Fuel Pressure, Airflow Sensor, O2 Sensor Circuit, Coolant Temperature Sensor, ECM
51	Faulty ECM ROM	Defective ECM
52	Faulty ECM RAM	Defective ECM
53	Pressure Regulator VSV	VSV/Circuit, ECM
54	Power Transistor (Grounded)	Transistor/Circuit, ECM
61	Airflow Sensor	Sensor/Circuit, ECM
62	Airflow Sensor	Sensor/Circuit, ECM
63	Vehicle Speed Sensor	Sensor/Circuit, ECM
64	Fuel Injector Circuit (ECM Transistor)	Wiring Harness, ECM
65	Throttle Valve Switch (Full Throttle)	Switch/Circuit, ECM

Isuzu Rodeo S 1992 - ECM TERMINAL IDENTIFICATION

Fig. 3: Isuzu Rodeo S 1992 - Component Locations - ECM Terminal Identification

Isuzu Rodeo S 1992 - DIAGNOSTIC CIRCUIT CHECK

Fig. 4: Isuzu Rodeo S 1992 - Component Locations - Diagnostic Circuit Check Flow Chart

Isuzu Rodeo S 1992 - TEST NO. 1 - ECM POWER SUPPLY

Checking ECM Unit Power Supply Circuit

Isuzu Rodeo S 1992 - Confirmation

1. Disconnect ECM unit harnesses at connectors.
2. Turn key switch to ON position.
3. Check that power voltage is present at connector terminals No. 33, 12 or 21.
4. Check that continuity exists between the connector terminals No. 11, 20 and ground.

Isuzu Rodeo S 1992 - Inspection And Correction

1. When power voltage is not present at terminals No. 33 and 12 or 21. Check the main relay, starter switch, fuses, fusible link wires and related circuits and correct or replace the parts as necessary.
2. if the circuit tester does not indicate continuity across the terminals No. 11, 20 and ground, correct or replace grounding cable.
3. Connect the ECM unit harnesses at connector properly.

Fig. 5: Isuzu Rodeo S 1992 - Component Locations - Test No. 1 Schematic - ECM Power Supply

Isuzu Rodeo S 1992 - TEST NO. 2 - CHECK ENGINE LIGHT INOPERATIVE

NOTE:

Before replacing ECM, use an ohmmeter and check resistance of each ECM controlled relay and solenoid coil. See ECM wiring diagram for coil terminal identification for solenoid(s) and relay(s) to be checked. Replace any relay or solenoid if the coil resistance measures less than 20 ohms.

Fig. 6: Isuzu Rodeo S 1992 - Component Locations - Test No. 2 Schematic, Check Engine Light Inoperative

Fig. 7: Isuzu Rodeo S 1992 - Component Locations - Test No. 2 Flow Chart, Check Engine Light Inoperative

Isuzu Rodeo S 1992 - TEST NO. 3 - WILL NOT FLASH CODE NO. 12

Fig. 8: Isuzu Rodeo S 1992 - Component Locations - Test No. 3 Schematic, Won't Flash Code No. 12

Fig. 9: Isuzu Rodeo S 1992 - Component Locations - Test No. 3 Flow Chart, Won't Flash Code No. 12

Isuzu Rodeo S 1992 - CODE 12 - SYSTEM NORMAL

Code No. 12 is always displayed when the key is ON and the engine is not running and it only means that the engine is not running. This code No. 12 is not stored in memory.

NOTE:

If the signal code No. 12 only is displayed when the function key is operated after clearing the memory, it indicates that the ECM electrical circuits and self diagnosis system are functioning normally.

Isuzu Rodeo S 1992 - CODE 13 - OXYGEN SENSOR CIRCUIT

Fig. 10: Isuzu Rodeo S 1992 - Component Locations - Code No. 13 Schematic, Oxygen Sensor Circuit

Fig. 11: Isuzu Rodeo S 1992 - Component Locations - Code No. 13 Component Diagram, Secondary Air Injection Check

Fig. 12: Isuzu Rodeo S 1992 - Component Locations - Code No. 13 Flow Chart, Oxygen Sensor Circuit

Isuzu Rodeo S 1992 - CODE 14 & 15 - COOLANT TEMPERATURE SENSOR

Fig. 13: Isuzu Rodeo S 1992 - Component Locations - Code No. 14, 15 Schematic, Coolant Temperature Sensor

Fig. 14: Isuzu Rodeo S 1992 - Component Locations - Code No. 14, 15 Connector, Coolant Temperature Sensor

Fig. 15: Isuzu Rodeo S 1992 - Component Locations - Code No. 14 Flow Chart, Shorted CTS Sensor

Fig. 16: Isuzu Rodeo S 1992 - Component Locations - Code No. 15 Flow Chart, Open CTS Sensor

Isuzu Rodeo S 1992 - CODE 21 - THROTTLE VALVE SWITCH (IDLE & FULL THROTTLE)

Isuzu Rodeo S 1992 THROTTLE VALVE SWITCH RESISTANCE

Accelerator Pedal Position	Continuity I - P (Ohms)	Continuity P - F (Ohms)
Not Depressed	0	Infinity
Slightly Depressed	Infinity	Infinity
Fully Depressed	Infinity	0

Fig. 17: Isuzu Rodeo S 1992 - Component Locations - Code No. 21 Schematic, Throttle Valve Switch

Fig. 18: Isuzu Rodeo S 1992 - Component Locations - Code No. 21 Connector, Throttle Valve Switch

Fig. 19: Isuzu Rodeo S 1992 - Component Locations - Code No. 21 Flow Chart, Throttle Valve Switch

Isuzu Rodeo S 1992 - CODE 22 - STARTER SIGNAL

NOTE:

Starter relay is located in relay box, in engine compartment.

Fig. 20: Isuzu Rodeo S 1992 - Component Locations - Code No. 22 Schematic, Starter Signal

Fig. 21: Isuzu Rodeo S 1992 - Component Locations - Code No. 22 Flow Chart, Starter Signal

Isuzu Rodeo S 1992 - CODE 23, 35 & 54 - POWER TRANSISTOR CIRCUIT Diagnostic Aid

If code 23 is displayed, there should be no continuity between circuit 5 and ground. If code 35 is displayed, there should be continuity between STAY of power transistor and intake manifold. If code 54 is displayed, there should be continuity between circuit 10 and ground.

Fig. 22: Isuzu Rodeo S 1992 - Component Locations - Code No. 23, 35, 54 Schematic, Power Transistor Circuit

Fig. 23: Isuzu Rodeo S 1992 - Component Locations - Code No. 23, 35, 54 Flow Chart, Power Transistor Circuit

Isuzu Rodeo S 1992 - CODE 25 & 53 - PRESSURE REGULATOR VSV Diagnostic Aid

If code 25 is displayed, voltage between BLACK/WHITE wire and ground should be 12 volts and resistance between LIGHT GRAY/YELLOW wire and circuit No. 4 should be zero. If code 53 is displayed, resistance between circuits No. 9 and 10 and ground should be zero.

Fig. 24: Isuzu Rodeo S 1992 - Component Locations - Code No. 25, 53 Schematic, Pressure Regulator VSV

Fig. 25: Isuzu Rodeo S 1992 - Component Locations - Code No. 25, 53 Connector, Pressure Regulator VSV

Fig. 26: Isuzu Rodeo S 1992 - Component Locations - Code No. 25, 53 Flow Chart, Pressure Regulator VSV

Isuzu Rodeo S 1992 - CODE 26 & 27 - CANISTER PURGE VSV

Fig. 27: Isuzu Rodeo S 1992 - Component Locations - Code No. 26, 27 Schematic, Canister Purge VSV

Fig. 28: Isuzu Rodeo S 1992 - Component Locations - Code No. 26, 27 Connector, Canister Purge VSV

Fig. 29: Isuzu Rodeo S 1992 - Component Locations - Code No. 26, 27 Flow Chart, Canister Purge VSV

Isuzu Rodeo S 1992 - CODE 32 - EGR SYSTEM MALFUNCTION Specified Reappearance Pattern

1. Run engine at idle condition, at normal operating temperature.
2. Keep at idle for more than 10 seconds, with vehicle stopped
3. Drive vehicle at just over 10 MPH. Accelerate quickly to more than 30 MPH (must reach 30 MPH within 10 seconds of starting acceleration).
4. Within 30 seconds, decelerate safely to a complete stop. See Fig. 30 .
5. Repeat above procedure 2) through 4) several times.

Fig. 30: Isuzu Rodeo S 1992 - Component Locations - Code No. 32 Acceleration Chart

Fig. 31: Isuzu Rodeo S 1992 - Component Locations - Code No. 32 Flow Chart, EGR System Malfunction (1 of 3)

Fig. 32: Isuzu Rodeo S 1992 - Component Locations - Code No. 32 Flow Chart, EGR System Malfunction (2 of 3)

Fig. 33: Isuzu Rodeo S 1992 - Component Locations - Code No. 32 Flow Chart, EGR System Malfunction (3 of 3)

Isuzu Rodeo S 1992 - CODE 33 - FUEL INJECTOR CIRCUIT (OPEN OR GROUNDED)

Fig. 34: Isuzu Rodeo S 1992 - Component Locations - Code No. 33 Schematic, Fuel Injector Circuit

Fig. 35: Isuzu Rodeo S 1992 - Component Locations - Code No. 33 Flow Chart, Fuel Injector Circuit

Isuzu Rodeo S 1992 - CODE 34 - EGR GAS TEMPERATURE SENSOR Diagnostic Aid

Resistance between ECM terminal 26 and GRY/YEL and between ECM terminal 38 and BLK should be zero ohms. Resistance between ECM terminal 38 and ground should be zero ohms. Resistance between ECM terminals 11 and 20 and ground should be zero.

Fig. 36: Isuzu Rodeo S 1992 - Component Locations - Code No. 34 Schematic, EGR Gas Temperature Sensor

Fig. 37: Isuzu Rodeo S 1992 - Component Locations - Code No. 34 Connector, EGR Gas Temperature Sensor

Fig. 38: Isuzu Rodeo S 1992 - Component Locations - Code No. 34 Flow Chart, EGR Gas Temperature Sensor (1 of 2)

Fig. 39: Isuzu Rodeo S 1992 - Component Locations - Code No. 34 Flow Chart, EGR Gas Temperature Sensor (2 of 2)

Isuzu Rodeo S 1992 - CODE 35 - POWER TRANSISTOR CIRCUIT

See Code No. 23.

Isuzu Rodeo S 1992 - CODE 41 - CRANK ANGLE SENSOR SIGNAL

NOTE:

Wire colors may vary. See WIRING DIAGRAMS article in the ENGINE PERFORMANCE Section..

Isuzu Rodeo S 1992 - Diagnostic Aid

1. Disconnect crank angle sensor harnesses at crank angle sensor connector.
2. Disconnect all connectors at ECM.
3. Turn ignition ON. Measure resistance between terminals 34 and WHITE, 35 and GREEN and BLACK and ground. Resistance should be zero.
4. Measure voltage between GREEN/BLACK and ground. Voltage should be 10-14 volts.
5. When circuit is found to be in normal condition, replace distributor assembly.

Fig. 40: Isuzu Rodeo S 1992 - Component Locations - Code No. 41 Schematic, Crank Angle Sensor Circuit

Fig. 41: Isuzu Rodeo S 1992 - Component Locations - Code No. 41 Connector, Crank Angle Sensor Circuit

Fig. 42: Isuzu Rodeo S 1992 - Component Locations - Code No. 41 Flow Chart, Crank Angle Sensor Circuit

Isuzu Rodeo S 1992 - CODE 43 & 65 - THROTTLE VALVE SWITCH

Isuzu Rodeo S 1992 THROTTLE VALVE SWITCH RESISTANCE

Accelerator Pedal Position	Continuity I - P (Ohms)	Continuity P - F (Ohms)
Not Depressed	0	Infinity
Slightly Depressed	Infinity	Infinity
Fully Depressed	Infinity	0

Fig. 43: Isuzu Rodeo S 1992 - Component Locations - Code No. 43, 65 Schematic, Throttle Valve Switch

Fig. 44: Isuzu Rodeo S 1992 - Component Locations - Code No. 43, 65 Connector, Throttle Valve Switch

Fig. 45: Isuzu Rodeo S 1992 - Component Locations - Code No. 43, 65 Flow Chart, Throttle Valve Switch

Isuzu Rodeo S 1992 - CODE 44 & 45 - OXYGEN SENSOR-LEAN/RICH FUEL MIXTURE

Fig. 46: Isuzu Rodeo S 1992 - Component Locations - Code No. 44, 45 Schematic, O2 Sensor-Lean/Rich Fuel Mixture

Fig. 47: Isuzu Rodeo S 1992 - Component Locations - Code No. 44, 45 Schematic, O2 Sensor-Lean/Rich Fuel Mixture

Fig. 48: Isuzu Rodeo S 1992 - Component Locations - Code No. 44, 45 Flow Chart, O2 Sensor-Lean/Rich Fuel Mixture

Isuzu Rodeo S 1992 - Fuel Metering Lean-Faulty Inspection Procedure

Fig. 49: Isuzu Rodeo S 1992 - Component Locations - Fuel Metering Lean Fault Flow Chart

Isuzu Rodeo S 1992 - Fuel Metering Rich Faulty Inspection Procedure

Fig. 50: Isuzu Rodeo S 1992 - Component Locations - Fuel Metering Rich Fault Schematic

Fig. 51: Isuzu Rodeo S 1992 - Component Locations - Fuel Metering Rich Fault Flow Chart

Isuzu Rodeo S 1992 - CODE 51 & 52 - FAULTY ECM RAM/ROM Circuit Connections

1. Disconnect the control unit harnesses at connector and check for proper connections at terminals.
2. Regardless of terminal conditions, road test the vehicle with all the harnesses reconnected at the connector.
3. Obtain display of trouble code and see if the trouble has been corrected. If the trouble persists, replace the ECM.

Isuzu Rodeo S 1992 - CODE 53 - PRESSURE REGULATOR VSV

See Code No. 25.

Isuzu Rodeo S 1992 - CODE 54 - POWER TRANSISTOR CIRCUIT

See Code No. 23.

Isuzu Rodeo S 1992 - CODE 61 & 62 - AIRFLOW SENSOR SIGNAL Inspection Of Airflow Sensor

Uncover the rubber boot on the air flow sensor side of the harness connector. Check resistance an voltage of terminals. See AIRFLOW SENSOR SIGNAL table.

Isuzu Rodeo S 1992 AIRFLOW SENSOR SIGNAL

Wiring	Ignition Switch	Volts	Resistance (Ohms)
Red-Ground	ON	10 - 14	0
Red-Ground	ON	Below 0.2	0
White-Ground	ON (1)	0.5-1.5	0
Black-Ground	ON/OFF	Below 0.2	0
(1) While breathing.

Isuzu Rodeo S 1992 CIRCUIT WIRING RESISTANCE

Wiring	Resistance (Ohms)
W To Circuit 31	0
W To Ground	Infinity
R To Circuit 32	0
R To Ground	Infinity
B to Circuit 40	0

Fig. 52: Isuzu Rodeo S 1992 - Component Locations - Code No. 61, 62 Schematic, Airflow Sensor Signal

Fig. 53: Isuzu Rodeo S 1992 - Component Locations - Code No. 61, 62 Flow Chart, Airflow Sensor Signal (1 of 2)

Fig. 54: Isuzu Rodeo S 1992 - Component Locations - Code No. 61, 62 Flow Chart, Airflow Sensor Signal (2 of 2)

Isuzu Rodeo S 1992 - CODE 63 - VEHICLE SPEED SENSOR SIGNAL

Code 63 may be displayed even if the system is normal if the vehicle is used under the following conditions:

• A/T; In "D" range, while depressing the brake pedal, the accelerator pedal is depressed over 1/2 throttle for more than 3 seconds
• M/T; Under the severe climbing conditions, keep the vehicle stopped while the accelerator pedal depressed over 1/2 throttle for more than 3 seconds

Isuzu Rodeo S 1992 - Sensor & Equipment

1. Connect a circuit tester between the control unit harness connector terminal 41 and ground.
2. Disconnect speedometer cable at transmission end and turn the inner cable slowly.
3. If the tester indicates continuity and open circuit condition alternately as the cable is turned, the car speed sensor and circuit are operating normally

Isuzu Rodeo S 1992 - Wiring Circuits

Check resistance between YELLOW and Circuit 41, See Fig. 55 , reading should be zero ohms. Check resistance between BLACK and ground, there should be infinite resistance.

Isuzu Rodeo S 1992 - Car Speed Sensor

1. Remove the speedometer assembly.
2. Connect the leads of a circuit tester across terminals 1 and 2 at rear face of the meter assembly. See Fig. 56 .
3. Turn the inner shaft slowly and check that the tester indicates a continuity and open circuit condition alternately. If speed sensor is inoperative, replace speedometer assembly.

Fig. 55: Isuzu Rodeo S 1992 - Component Locations - Code No. 63 Schematic, Vehicle Speed Sensor Signal

Fig. 56: Isuzu Rodeo S 1992 - Component Locations - Code No. 63 Speed Sensor Check

Fig. 57: Isuzu Rodeo S 1992 - Component Locations - Code No. 63 Flow Chart, Vehicle Speed Sensor Signal

Isuzu Rodeo S 1992 - CODE 64 - FUEL INJECTOR CIRCUIT (ECM TRANSISTOR)

Fig. 58: Isuzu Rodeo S 1992 - Component Locations - Code No. 64 Schematic, Fuel Injector Ckt. (ECM Transistor)

Fig. 59: Isuzu Rodeo S 1992 - Component Locations - Code No. 64 Harness Connectors, Fuel Injector Ckt. (ECM Transistor)

Fig. 60: Isuzu Rodeo S 1992 - Component Locations - Code No. Flow Chart, Fuel Injector Ckt. (ECM Transistor)

Isuzu Rodeo S 1992 - CODE 65 - THROTTLE VALVE SWITCH

See Code No. 43.

Isuzu Rodeo S 1992 - SUMMARY

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