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Isuzu Trooper LS 1990 - 1990 ENGINE PERFORMANCE Self-Diagnostics - Amigo, Pickup & Trooper Fuel Injection 2.6L
Isuzu Trooper LS 1990 - INTRODUCTION
If no faults were found while performing BASIC TESTING , proceed with ENTERING SELF-DIAGNOSTICS. If no fault codes or only pass codes are present, proceed to H - TESTS W/O CODE (F INJ) article for diagnosis by symptom (i.e. ROUGH IDLE, NO START, etc.).
Isuzu Trooper LS 1990 - SELF-DIAGNOSTIC SYSTEM HARD FAILURES
Hard failures cause CHECK ENGINE light to illuminate 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, the vehicle runs but driveability will not be optimum.
Isuzu Trooper LS 1990 - INTERMITTENT FAILURES
Intermittent failures may cause CHECK ENGINE light to flicker or illuminate and go out after the intermittent fault goes away. However, the 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 H - TESTS W/O CODE (F INJ) article.
Isuzu Trooper LS 1990 - RETRIEVING CODES
NOTE: Codes can also be retrieved using a Scan tester.
- The 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, code is present.
- If light did not come on with key on and engine off, the CHECK ENGINE light circuit must be checked before continuing. See AMIGO, PICKUP & TROOPER DIAGNOSTIC CIRCUIT CHECK in this article if CHECK ENGINE light failed to operate. Circuit checks are located within code charts.
- To retrieve codes, turn ignition on. Install jumper wire between diagnostic leads. See Fig. 1 . Count number of flashes from CHECK ENGINE light. A Code 12 is identified by a flash, pause and flash, flash. A long pause occurs and Code 12 repeats 3 times. See Fig. 2 . Each additional code flashes 3 times starting with lowest code to the highest and repeat 3 times.
- If system is operating properly (with no codes), a Code 12 should exist with ignition on and engine off. This indicates the diagnostic system is capable of storing codes.
- Each additional code repeats 3 times and then the next code follows. See Fig. 2 . Once all codes are displayed, codes will repeat. After codes are retrieved, remove jumper wire from diagnostic leads to exit diagnostic mode.
Fig. 1: Isuzu Trooper LS 1990 - Component Locations - Locating Diagnostic Leads
Fig. 2: Isuzu Trooper LS 1990 - Component Locations - Displaying Codes
Isuzu Trooper LS 1990 - CLEARING CODES
After repairs are performed, clear ECM memory of all stored codes. To clear memory, turn ignition off and remove appropriate fuse from fuse block. See CLEARING CODES table.
Isuzu Trooper LS 1990 CLEARING CODES
Application Fuse Number Amigo & Pickup (1) 3 Trooper (2) 6
(1) Fuse is located in instrument panel fuse block. Code can also be cleared by removing MAIN fuse (60A), located in engine compartment fuse block.
(2) Fuse is located in fuse block, on left front corner of engine compartment.
Isuzu Trooper LS 1990 ECM LOCATIONS
Model Location Amigo & Pickup Near Left Kick Panel Trooper Below Center Console Between Seats
Isuzu Trooper LS 1990 - DIAGNOSTIC CIRCUIT CHECK
Fig. 3: Isuzu Trooper LS 1990 - Component Locations - Flow Chart - Diagnostic Circuit Check
Isuzu Trooper LS 1990 - TROUBLE CODE CHARTS
Isuzu Trooper LS 1990 TROUBLE CODE IDENTIFICATION
Code System Affected Probable Cause 12 System Normal System Normal 13 O2 Sensor Circuit Sensor/Circuit, ECM 14 Coolant Temp. (Shorted) Temp. Sensor/Circuit, ECM Sensor 15 Coolant Temp. (Open) Temp. Sensor/Circuit, ECM Sensor 21 Throttle Valve Switch (Idle & Full Throttle) Switch/Circuit, ECM 22 Starter Signal Circuit, ECM 23 Power Transistor (Shorted) Transistor/Circuit, ECM 25 Press. 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 Temp. 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 Press., Airflow Sensor, O2 Sensor Circuit Cool. Temp. Sensor, ECM 45 O2 Sensor (Lean/Rich) Injectors, Fuel Press., Airflow Sensor, O2 Sensor Circuit Cool. Temp. Sensor, ECM 51 Faulty ECM ROM Defective ECM 52 Faulty ECM RAM Defective ECM 53 Press. 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 Trooper LS 1990 - ECU TERMINAL IDENTIFICATION
Fig. 4: Isuzu Trooper LS 1990 - Component Locations - ECU Terminal Identification
Isuzu Trooper LS 1990 - TEST 1: ECM POWER SUPPLY
Isuzu Trooper LS 1990 - TEST 2: "CHECK ENGINE" LIGHT INOP
Isuzu Trooper LS 1990 - TEST 3: WILL NOT FLASH CODE 12
Isuzu Trooper LS 1990 - CODE 12: SYSTEM NORMAL
Code 12 is always displayed when the key is in the "ON" position and the engine is not running and ONLY means that the engine is not running. Code 12 is not stored in memory.
NOTE: If Code 12 is only displayed when the function key is operated after clearing the memory, it indicates that the ECM electrical circuits and self-diagnosis system are functioning properly.
Isuzu Trooper LS 1990 - CODE 13: O2 SENSOR CIRCUIT
Isuzu Trooper LS 1990 - CODE 14: COOLANT TEMP SENSOR SHORTED
Isuzu Trooper LS 1990 - CODE 15: COOLANT TEMP SENSOR OPEN
Isuzu Trooper LS 1990 - CODE 21: THROTTLE VALVE SWITCH (IDLE & FULL THROTTLE)
Isuzu Trooper LS 1990 - CODE 22: STARTER SIGNAL
Isuzu Trooper LS 1990 - CODE 23: POWER TRANSISTOR CIRCUIT
Isuzu Trooper LS 1990 - CODE 25: PRESSURE REGULATOR VSV
Isuzu Trooper LS 1990 - CODE 26 & 27: CANISTER PURGE VSV
Isuzu Trooper LS 1990 - CODE 32: EGR SYSTEM MALFUNCTION
Fig. 19: Isuzu Trooper LS 1990 - Component Locations - Code 32: Specified Reappearance Pattern
Isuzu Trooper LS 1990 - CODE 33: FUEL INJECTOR CIRCUIT (OPEN OR GROUNDED)
Fig. 21: Isuzu Trooper LS 1990 - Component Locations - Code 33: Circuit Diagram Fuel Injector
Isuzu Trooper LS 1990 - CODE 34: EGR GAS TEMPERATURE SENSOR
Fig. 22: Isuzu Trooper LS 1990 - Component Locations - Code 34: Flow Chart EGR Temp Sensor (1 of 2)
Fig. 23: Isuzu Trooper LS 1990 - Component Locations - Code 34: Flow Chart EGR Temp Sensor (2 of 2)
Fig. 24: Isuzu Trooper LS 1990 - Component Locations - EGR Gas Temperature Sensor Circuit Diagram
Isuzu Trooper LS 1990 - CODE 35: POWER TRANSISTOR CIRCUIT
Fig. 25: Isuzu Trooper LS 1990 - Component Locations - Code 35: Flow Chart Power Transistor Circuit
Isuzu Trooper LS 1990 - CODE 41: CRANK ANGLE SENSOR SIGNAL
Fig. 26: Isuzu Trooper LS 1990 - Component Locations - Code 41: Flow Chart Crank Angle Sensor Signal
Isuzu Trooper LS 1990 - CODE 43: THROTTLE VALVE SWITCH
Fig. 28: Isuzu Trooper LS 1990 - Component Locations - Code 43: Flow Chart Throttle Valve Switch
Isuzu Trooper LS 1990 - CODE 44 & 45: O2 SENSOR - LEAN/RICH FUEL MIXTURE
Fig. 31: Isuzu Trooper LS 1990 - Component Locations - Code 44 & 45: O2 Sensor Circuit Diagram
Isuzu Trooper LS 1990 - FUEL METERING LEAN FAULTY INSPECTION PROCEDURE
Isuzu Trooper LS 1990 - FUEL METERING RICH FAULTY INSPECTION PROCEDURE
Isuzu Trooper LS 1990 - CODE 51 & 52: FAULTY ECM RAM/ROM Circuit Connections
- Disconnect the control unit harnesses at connector and check for proper connections at terminals.
- Regardless of terminal conditions, road test the vehicle with all the harnesses reconnected at the connector.
- Obtain display of trouble code and see if the trouble has been corrected. If the trouble persists, replace ECM.
Isuzu Trooper LS 1990 - Test
Start engine. Is code 51, 52 displayed? If not, end of test. If yes, replace ECM.
Isuzu Trooper LS 1990 - CODE 53: PRESSURE REGULATOR VSV
Isuzu Trooper LS 1990 - CODE 54: POWER TRANSISTOR CIRCUIT
Isuzu Trooper LS 1990 - CODE 61 & 62: AIRFLOW SENSOR CIRCUIT
Fig. 38: Isuzu Trooper LS 1990 - Component Locations - Airflow Sensor Schematic & Circuit Voltages
Isuzu Trooper LS 1990 - CODE 63: VSS SIGNAL
Fig. 40: Isuzu Trooper LS 1990 - Component Locations - Code 63: Car Speed Sensor Test & Test Points
Isuzu Trooper LS 1990 - CODE 64: FUEL INJECTOR CIRCUIT (ECM TRANSISTOR)
Fig. 42: Isuzu Trooper LS 1990 - Component Locations - Location Of Test Connector "H14"
Isuzu Trooper LS 1990 - CODE 65: THROTTLE VALVE SWITCH
Fig. 43: Isuzu Trooper LS 1990 - Component Locations - Code 65: Flow Chart, Throttle Valve Switch
Isuzu Trooper LS 1990 - SUMMARY
If no hard fault codes (or only pass codes) are present, driveability symptoms exist or intermittent codes exist, proceed to H - TESTS W/O CODE (F INJ) article for diagnosis by symptom (i.e. ROUGH IDLE, NO START, etc.) or intermittent diagnosis procedures.