Engine Controls - Tests W/codes - 4.3L: Other Oldsmobile Bravada II

Hard Failures

Most hard failures cause MIL to illuminate and remain on until malfunction is repaired. If MIL comes on and remains on (light may flash) during vehicle operation, cause of malfunction must be determined. See DIAGNOSTIC PROCEDURE .

If a sensor fails, PCM/VCM will use a substitute value in its calculations to continue engine operation. In this condition, vehicle is functional, but it will most likely display degraded driveability.

Intermittent Failures

Intermittent failures cause MIL to flicker or glow and go out about 10 seconds after intermittent fault goes away. Corresponding DTC, however, will be retained in PCM/VCM memory. If related fault does not reoccur within 50 engine starts, trouble code will be erased from control module memory. Intermittent failures may be caused by sensor, connector or wiring related problems. See INTERMITTENTS in TESTS W/O CODES - 4.3L article.

Note. OBD II vehicles have options available in the scan tool DTC mode to display enhanced information available. However, to fully utilize information and procedures requires the use of a Tech 1 or 2 scan tool. See scan tool operator's manual for additional information.

The following are Tech 1 or 2 scan tool sub-menus in the DTC INFO and SPECIFIC DTC modes

FAIL THIS IGN.

This selection will display all DTCs that have failed during the present ignition cycle.

HISTORY

This selection will display only DTC(s) that are stored in the control module's history memory. It will not type "B" DTCs. It will display all type "A" and type "B" DTCs that have the MIL illuminated and have failed within the last 40 warm-up cycles. It will also display type "C" DTCs that have failed within the 40 warm-up cycles.

MIL REQUEST

This selection will display only DTCs that are requesting the MIL. Type "C" DTCs cannot be displayed using this option. This selection will report type "B" DTCs only after the MIL has been requested.

NOT RUN SCC

Not Run Since Code Clear option will display up to 33 DTCs that have not run since DTCs were last cleared. Since any displayed DTCs have not run, their condition (passing or failing) is unknown.

FAILED SINCE CLEAR

This message indicates the DTC has failed at least once within the last 40 warm-up cycles since the last time DTCs were cleared.

NOT RUN SINCE CL.

Not Run Since Cleared message indicates that the selected diagnostic test has not run since the last time DTCs were cleared. Therefore, the diagnostic test status (passed or failed) is unknown. After DTCs are cleared, this message will continue to be displayed until the diagnostic test runs.

NOT RUN THIS IGN.

Not Run This Ignition message indicates the selected diagnostic test has not run this ignition cycle.

MIL INOPERATIVE

1. Perform «POWERTRAIN ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-33422-S03507999212001122000000) , then go to next step.
2. Turn engine off for 15 seconds. Turn ignition on with engine off. If Malfunction Indicator Light (MIL) illuminates, go to step 4). If MIL does not illuminate, go to next step.
3. Start engine. If engine starts, go to step 6). If engine does not start, go to step 7).
4. Install scan tool. Turn ignition on. Using scan tool, command MIL to turn on and off. If MIL turns on and off as commanded, go to step 25). If MIL does not turn on and off as commanded, go to next step.
5. Turn ignition off. Disconnect VCM harness connectors. Turn ignition on. If Malfunction Indicator Light (MIL) illuminates, go to step 19). If MIL does not illuminate, go to step 11).
6. Turn ignition off. Disconnect VCM harness connectors. Turn ignition on. Using a fused jumper connected to ground, probe VCM harness connector MIL control circuit. See WIRING DIAGRAMS - 4.3L article. If MIL illuminates, go to step 11). If MIL does not illuminate, go to step 8).
7. Check for open in ignition and battery fuses. If fuses are okay, go to step 9). If fuse(s) is open, go to step 10).
8. Check for open in fused jumper. If fused jumper is okay, go to step 13). If fused jumper is open, go to step 14).
9. Turn ignition off. Disconnect VCM harness connectors. Turn ignition on. Using a test light connected to ground, probe VCM harness connector ignition feed circuit. See WIRING DIAGRAMS - 4.3L article. If test light illuminates, go to step 18). If test light does not illuminate, go to step 20).
10. Check for short to ground in fuse circuit that was open. Repair as necessary and replace fuse. After repairs, go to step 25).
11. Check for faulty VCM connections. If connections faulty okay, go to step 23). If connections are okay, go to step 24).
12. Repair open in ignition feed circuit. After repairs, go to step 25).
13. Repair short to voltage in MIL control circuit. After repairs, go to step 25).
14. Check for open in MIL control circuit. See WIRING DIAGRAMS - 4.3L article. Repair as necessary. After repairs, go to step 23). If circuit is okay, go to next step.
15. Check for open in ignition feed circuit or fuse to MIL. See WIRING DIAGRAMS - 4.3L article. Repair as necessary. After repairs, go to step 23). If circuit or fuse is okay, go to next step.
16. Check for an open MIL bulb. If light bulb is faulty, go to step 23). If light bulb is okay, go to next step.
17. Replace instrument panel assembly. After replacing instrument panel, go to step 25).
18. Turn ignition off. Disconnect VCM harness connectors. Turn ignition on. Using test light connected to ground, probe VCM harness connector battery feed circuit. See WIRING DIAGRAMS - 4.3L article. If test light illuminates, go to step 21). If test light does not illuminate, go to step 22).
19. Repair short to ground in MIL control circuit. After repairs, go to step 25).
20. Repair open in ignition feed circuit. After repairs, go to step 25).
21. Check for faulty VCM ground connection at engine block. Repair as necessary. After repairs, go to step 23). If connections were okay, go to step 11).
22. Repair open in battery feed circuit. After repairs, go to step 25).
23. Repair as necessary. After repairs, go to step 25).
24. Replace VCM. Perform VCM relearn procedures. After repairs, go to next step.
25. Warm engine to normal operating temperature. Check if any DTC(s) are set. Diagnose any DTC present. If DTC(s) are not present, system is okay.

SUMMARY

If no hard fault codes are present, driveability symptoms exist or intermittent DTC(s) exist, proceed to TESTS W/O CODES - 4.3L article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.

IAT TEMPERATURE-TO-RESISTANCE VALUES

IAT TEMPERATURE-TO-RESISTANCE VALUES

ECT TEMPERATURE-TO-RESISTANCE VALUES

ECT TEMPERATURE-TO-RESISTANCE VALUES