Engine Controls - Basic Testing: Other Isuzu Trooper II

Compression

Check engine mechanical condition with a compression gauge, vacuum gauge, or an engine analyzer. See engine analyzer manual for specific instructions.

Exhaust System Backpressure

The exhaust system can be checked with a vacuum or pressure gauge. If using a pressure gauge, remove oxygen sensor or air injection check valve (if equipped). Connect a 0-5 psi pressure gauge and run engine at 2000 RPM. If exhaust system backpressure is greater than 2 psi, exhaust system or catalytic converter is plugged.

If a vacuum gauge is used, connect vacuum gauge hose to intake manifold vacuum port and start engine. Observe vacuum gauge, while opening throttle part way and hold steady. If vacuum gauge reading slowly drops after stabilizing, check exhaust system for restriction.

FUEL SYSTEM

FUEL SYSTEM PRESSURE RELEASE

1. Loosen fuel tank filler cap to relieve tank pressure. Remove fuel pump relay from underhood fuse/relay box. Start and operate engine until it stalls. Crank engine an additional 30 seconds.
2. Loosen hose clamp of fuel line on side of pressure regulator, coming from fuel line inlet distributor pipe. Cover fuel hose with a shop towel, and slowly pull hose from pressure regulator to relieve fuel pressure. When fuel stops leaking, reinstall hose and clamp.

Ignition Coil

Information is not available from manufacturer.

Ignition System Check

See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK under appropriate TROUBLE SHOOTING.

IDLE SPEED & IGNITION TIMING

For adjustment procedures, see ADJUSTMENTS article.

IDLE SPEED SPECIFICATIONS

IGNITION TIMING (Degrees BTDC @ RPM)

NO MALFUNCTION INDICATOR LIGHT (MIL)

1. Perform On-Board Diagnostic (OBD) System Check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-16258-S04817147262000122900000) . After performing OBD system check, go to next step.
2. Attempt to start engine. If engine does not start, go to step 6). If engine starts, go to next step.
3. Check METER GAUGE fuse C-10 (10-amp) located in dash fuse box. If fuse is okay, go to next step. If fuse is blown, go to step 16).
4. Turn ignition on. Using test light connected to ground, probe ignition feed circuit at instrument cluster terminal No. 14 (Blue/Yellow wire). If test light illuminates, go to next step. If test light does not illuminate, go to step 13).
5. Turn ignition off. Disconnect PCM C-1 electrical connector. Connect a jumper wire between ground and MIL control circuit at PCM connector C-1 terminal A13 (Purple wire). Turn ignition on. If MIL comes on, go to step 10). If MIL does not come on, go to step 11).
6. Check ENGINE fuse C-8 (15-amp) located in dash fuse box. Check PCM fuse F-3 (30-amp) in fuse/relay box located in engine compartment. If fuses are okay, go to next step. If fuses are blown, go tostep 15).
7. Turn ignition off. Disconnect PCM C-3 electrical connector. Turn ignition on. Using test light connected to ground, probe ignition feed circuits at PCM connector C-3 terminal E16 and F16 (Red/Blue wires). If test light illuminates, go to next step. If test light does not illuminate, go to step 12).
8. Using test light connected to ground, probe battery feed circuit at PCM connector C-1 terminal A4 (Red/White wire). If test light illuminates, go to next step. If test light does not illuminate, go tostep 14).
9. Check for faulty PCM ground connections. Repair as necessary. If connections are okay, go to next step.
10. Check PCM connectors for damaged terminals. If any terminals are damaged, replace PCM. If PCM connector terminals are okay, go to step 17).
11. Check for an open in MIL control circuit (Purple wire) between PCM and MIL. Repair as necessary. If circuit is okay, go to step 18).
12. Substitute PCM main relay with a known good relay. PCM main relay is located in fuse/relay box in engine compartment. Observe MIL. If MIL operates properly, replace PCM main relay. If MIL still does not operate, go to next step.
13. Repair open in ignition feed circuit (Black/Yellow wire) between PCM main relay and dash fuse box.
14. Repair open in PCM battery feed circuit (Red/White wire) between PCM and fuse/relay box located in engine compartment.
15. Repair short to ground in PCM ignition feed circuit (Black/Yellow or Red/Blue wire) or PCM battery feed circuit (Red/White wire). See appropriate wiring diagram in «WIRING DIAGRAMS»(ref-16267) article. Replace fuse.
16. Repair the short to ground in ignition feed circuit (Blue/Yellow wire) between instrument cluster and dash fuse box. Replace fuse.
17. Replace PCM. Verify proper system operation.
18. Check MIL driver circuit (Purple wire) for poor connection at instrument cluster connector. Repair as necessary. If no problem is found, diagnose problem in instrument cluster. See appropriate repair information.

MIL ON STEADY

1. Perform On-Board Diagnostic (OBD) System Check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-16258-S04817147262000122900000) . After performing OBD system check, go to next step.
2. Turn ignition off. Disconnect PCM C-1 electrical connector. Turn ignition on. If MIL comes on, go to next step. If MIL does not come on, go to step 5).
3. Turn ignition off. Disconnect instrument panel cluster connector. Check for short to ground in MIL control circuit (Purple wire) between PCM connector C-1 terminal A13 and instrument panel cluster. Repair as necessary. Repeat «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-16258-S04817147262000122900000) . If circuit is okay, go to next step.
4. Replace instrument panel cluster. See appropriate INSTRUMENT PANEL article in the instrument panel section. Repeat «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-16258-S04817147262000122900000) .
5. Turn ignition off. Reconnect PCM C-1 electrical connector. Turn ignition on. Reprogram EEPROM. Using scan tool, command MIL OFF. If MIL did not go off, go to next step. If MIL did go off, repeat «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-16258-S04817147262000122900000) .
6. Replace PCM. Repeat «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-16258-S04817147262000122900000) .

ENGINE CRANKS BUT WILL NOT RUN

1. Perform On-Board Diagnostic (OBD) System Check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-16258-S04817147262000122900000) . After performing OBD system check, go to next step.
2. Check IGNITION COIL fuse C-9 (15-amp) and ENGINE fuse C-8 (15-amp) located in dash fuse box. Check PCM fuse F-3 (30-amp) located in fuse/relay box in engine compartment. If any fuse is blown, go to next step. If fuses are okay, go to step 4).
3. Check for short to ground in appropriate circuits. See appropriate wiring diagram in «WIRING DIAGRAMS»(ref-16267) article. Repair as necessary. Replace any blown fuses.
4. Turn ignition off. Relieve fuel system pressure. See «FUEL SYSTEM PRESSURE RELEASE»(ref-16258-S18347914732000122900000) under FUEL SYSTEM. Install fuel pressure gauge to fuel supply line test fitting. Turn ignition on. If fuel pressure is 43-55 psi (2.9-3.9 kg/cm 2 ) and holds steady, go to step 5). If fuel pressure is not 43-55 psi (2.9-3.9 kg/cm 2 ) or does not hold steady, go to next step.
5. If no fuel pressure is indicated, go to «FUEL SYSTEM DIAGNOSIS»(ref-16258-S05241150392000122900000) . If any fuel pressure is indicated, go to «FUEL SYSTEM ELECTRICAL TEST»(ref-16258-S33701140552000122900000) .
6. Install Injector Tester (J-39021 ) at cylinder No. 2, and activate fuel injector. If fuel pressure drops, go to next step. If fuel pressure does not drop, go to step 18).
7. Install fuel injector noid light at cylinder No. 2 injector harness connector. Turn ignition on and crank engine. If noid light blinks, go to next step. If light does not blink, go to step 24).
8. Turn ignition off. Disconnect Ignition Control Module (ICM) 6-pin connector. Using a test light connected to battery voltage, probe each terminal of 6-pin connector while cranking engine. If test light flashes at each terminal, go to step 12). If test light does not flash at each terminal, go to next step.
9. Remove ICM 5-pin connector. Turn ignition on. Using a test light, verify module is being supplied with battery voltage at ICM 5-pin connector terminal No. 2 (Black/Yellow wire) and ground at ICM 5-pin connector terminal No. 1 (Black wire). If test light does not illuminate at both terminals, go to next step. If test light illuminates at both terminals, go to step 11).
10. Repair open in Black/Yellow wire between ICM and dash fuse box, or in Black wire between ICM and ground.
11. Repair or replace ICM as necessary.
12. Reconnect ICM 6-pin connector. Remove electrical connector from each ignition coil. Using a test light connected to battery voltage, probe each ignition coil terminal No. 2 (Green or Green with tracer wire) of coil connector. While cranking engine, observe test light. If test light does not flash at each coil connector, go to next step. If test light flashes at each coil connector, go to step 14).
13. Repair open in appropriate circuit between coil connector and ICM.
14. Turn ignition on. Ensure all coil connectors are disconnected. Using a test light connected to ground, probe ignition feed circuit to each ignition coil connector terminal No. 3 (Black/Orange wire). If test light does not illuminate at each terminal, go to next step. If test light illuminates at each terminal, go to step 15).
15. Repair open in Black/Orange wire between appropriate ignition coil and dash fuse box.
16. Ensure all coil connectors are disconnected. Using a test light connected to battery voltage, probe secondary ground circuit to each ignition coil connector terminal No. 1 (Black wire). If test light does not illuminate at each terminal, go to next step. If test light illuminates at each terminal, go to step 18).
17. Repair open in Black wire between appropriate ignition coil and ground.
18. Test for fuel contamination. If fuel is not contaminated, go to next step. If fuel is contaminated, clean fuel system as necessary. Replace fuel filter and verify all fuel injectors are delivering fuel.
19. Remove any ignition coil. Install spark tester at spark plug end of coil. While cranking engine, check ignition coil for crisp blue spark. If spark is okay, go to step 21). If poor or no spark is found, go to next step.
20. Replace faulty ignition coil. Repeat test from previous step for each ignition coil. Replace as necessary. Verify system is operating properly.
21. Repeat test from step 19) for each ignition coil. Test one coil at a time, and reinstall each coil on its spark plug when testing is complete ( DO NOT install screws). Start engine. If engine does not start, go to next step. If engine starts, install ignition coil screws and verify system is operating properly.
22. Remove all spark plugs. Inspect spark plugs for fouling, loose or missing electrodes, or cracked plugs. Clean or replace spark plugs as necessary. If spark plugs are okay, go to next step.
23. Check for these possible conditions: Faulty or incorrect camshaft belt. Incorrect valve timing. Leaking or sticking valves or rings. Leaking head gasket. Excessive valve deposits. Loose or worn rocker arms. Weak valve springs. If problem is found, repair as necessary. See appropriate repair information. If no problem is found, go to step 25).
24. Using scan tool, select ENGINE SPEED display. While cranking engine, observe scan tool. If RPM is indicated on scan tool, go to next step. If engine RPM is not indicated, go to step 34). NOTE: If scan tool is powered by cigarette lighter socket and display goes blank while cranking engine, it will be necessary to power scan tool directly from battery.
25. Disconnect Gray H-54 7-pin connector at rear of air cleaner (below where air duct attaches to MAF sensor). Turn ignition on. Using a test light connected to ground, probe ignition feed circuit at female side of connector H-54 terminal No. 1 (Red/Blue wire). If test light illuminates, go to next step. If test light does not illuminate, go to step 32).
26. Connect test light between female side of H-54 connector terminal No. 1 (Red/Blue wire) and each specified terminal. See «CONNECTOR H-54 TERMINAL/PIN IDENTIFICATION»(ref-16258-S12110483842000122900000) . Turn ignition on. If test light illuminates at any terminal, go to next step. If test light does not illuminate at any terminal, go to step 29). CONNECTOR H-54 TERMINAL/PIN IDENTIFICATION Application Terminal No. Wire Color Injector No. 1 6 Green/White Injector No. 2 5 Green/Orange Injector No. 3 3 Green Injector No. 4 2 Green/Red Injector No. 5 7 Green/Black Injector No. 6 4 Green/Yellow
27. Turn ignition off. Disconnect PCM C-3 electrical connector. Turn ignition on. If test light illuminates, go to next step. If test light does not illuminate, go to step 33).
28. Repair short to ground in appropriate injector driver circuit. See «CONNECTOR H-54 TERMINAL/PIN IDENTIFICATION»(ref-16258-S12110483842000122900000) .
29. Connect test light between female side of H-54 connector terminal No. 1 (Red/Blue wire) and each specified terminal. See «CONNECTOR H-54 TERMINAL/PIN IDENTIFICATION»(ref-16258-S12110483842000122900000) . Crank engine. If test light flashes at all terminals, go to step 31). If test light does not flash at all terminals, go to next step.
30. Check for open in appropriate injector driver circuit. See «CONNECTOR H-54 TERMINAL/PIN IDENTIFICATION»(ref-16258-S12110483842000122900000) . Repair as necessary. If circuit is okay, go to step 33).
31. Turn ignition off. Connect ohmmeter between male side of H-54 connector pin No. 1 (Red/Blue wire) and each specified pin. See «CONNECTOR H-54 TERMINAL/PIN IDENTIFICATION»(ref-16258-S12110483842000122900000) . If resistance is about 12.5 ohms at all pins, go to step 8). If resistance is not about 12.5 ohms at all pins, check for an open, shorted or faulty injector. Repair or replace as necessary.
32. Repair Red/Blue wire(s) between PCM connector C-3, PCM main relay (located in fuse/relay box in engine compartment) and H-54 connector.
33. Replace PCM. Verify system is operating properly.
34. Raise and support vehicle. Disconnect Crankshaft Position (CKP) sensor connector. Turn ignition on. Using a test light connected to ground, probe ignition feed circuit at CKP sensor harness terminal No. 1 (Yellow/Red wire). If test light illuminates, go to step 36). If test light does not illuminate, go to next step.
35. Repair open or short to ground in Yellow/Red wire between CKP sensor and PCM connector C-3.
36. Turn ignition on. Connect a test light between CKP sensor harness terminals No. 1 (Yellow/Red wire) and No. 3 (Yellow/Black wire). If test light illuminates, go to step 38). If test light does not illuminate, go to next step.
37. Repair open or short to voltage in Yellow/Black or Black/Blue wire between CKP sensor and ground.
38. Check for open or short in signal circuit (Yellow wire) between CKP sensor and PCM connector C-2. Repair as necessary. If circuit is okay, go to next step.
39. Replace CKP sensor. Verify system is operating properly. If system is still not operating properly, go to step 33).

MULTIPLE PCM INFORMATION SENSOR DTCS SET

1. Perform On-Board Diagnostic (OBD) System Check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-16258-S04817147262000122900000) . After performing OBD system check, go to next step.
2. Turn ignition off. Disconnect PCM electrical connectors. Turn ignition on. Check for poor connections, open or short in 5-volt reference circuit for affected sensors. See appropriate wiring diagram in «WIRING DIAGRAMS»(ref-16267) article. If problem is found, go to next step. If circuits are okay, go to next step.
3. Repair as necessary. Verify system is operating properly.
4. Check for poor connections or open in ground circuits of affected sensors. See appropriate wiring diagram in «WIRING DIAGRAMS»(ref-16267) article. If problem is found, go to next step. If connections and circuits are okay, go to step 6).
5. Repair as necessary. Verify system is operating properly.
6. Using DVOM, check voltage between ground and EGR pintle position sensor signal circuit at PCM connector C-1 harness terminal B7 (Yellow/Red wire). If no voltage exists, go to next step. If voltage exists, go to step 11). 7) Using DVOM, check voltage between ground and MAP sensor signal circuit at PCM connector C-3 harness terminal F8 (Red wire). If no voltage exists, go to next step. If voltage exists, go to step 14).
7. Using DVOM, check voltage between ground and TP sensor signal circuit at PCM connector C-3 harness terminal E8 (Blue wire). If no voltage exists, go to next step. If voltage exists, go to step 15).
8. Using DVOM, check voltage between ground and IAT sensor signal circuit at PCM connector C-1 harness terminal B8 (Yellow/Green wire). If no voltage exists, go to next step. If voltage exists, go tostep 16).
9. Using DVOM, check voltage between ground and ECT sensor signal circuit at PCM connector C-3 harness terminal E9 (Blue/Red wire). If no voltage exists, go to step 12). If voltage exists, go to step 17).
10. Using DVOM, check voltage between G sensor signal circuit at PCM connector C-1 harness terminal B-10 (Green/Red wire) and ground. If voltage does not exist, go to step 13). If voltage exists, go to step 19).
11. Disconnect EGR valve. Using DVOM, check voltage between ground and EGR pintle position sensor signal circuit at PCM connector C-1 harness terminal B7 (Yellow/Red wire). If no voltage exists, go to step 14). If voltage exists, go to step 20). NOTE: TFT sensor may also be referred to as A/T oil temperature sensor.
12. Using DVOM, check voltage between ground and TFT sensor signal circuit at PCM connector C-3 harness terminal E4 (Purple/White wire). If no voltage exists, go to step 22). If voltage exists, go tostep 12).
13. Replace EGR valve. Verify system is operating properly.
14. Repair short to voltage in Red wire between PCM connector C-3 and MAP sensor.
15. Repair short to voltage in Blue wire between PCM connector C-3 and TP sensor.
16. Repair short to voltage in Yellow/Green wire between PCM connector C-1 and IAT sensor.
17. Repair short to voltage in Blue/Red wire between PCM connector C-3 and ECT sensor.
18. Repair short to voltage in Green/Red wire between PCM connector C-1 and G sensor.
19. Repair short to voltage in Yellow/Red wire between PCM connector C-1 and EGR valve.
20. Repair short to voltage in Purple/White wire between PCM connector C-3 and TFT sensor.
21. Replace PCM. Repeat «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-16258-S04817147262000122900000) .

SUMMARY

If no faults were found while performing BASIC DIAGNOSTIC PROCEDURES, proceed to appropriate TESTS W/CODES article. If no hard codes are found in self-diagnostics, proceed to TESTS W/O CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.