Diagnostic Procedures
- Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM.
- Verify whether the instrument cluster is operational. If the instrument panel is completely inoperative, diagnose instrument cluster. Refer to ANALOG INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. Using scan tool, command the MIL ON and OFF. Does the MIL turn ON and OFF when commanded with a scan tool? If yes, problem is intermittent. If no, go to next step.
- Inspect the fuse that supplies ignition voltage to the cluster. Is fuse open? If yes, go to step 10. If no, go to next step.
- Turn ignition off. Remove fuse that supplies voltage to the cluster. Disconnect the PCM harness connector. Turn ignition on, with engine off. Measure voltage from the MIL control circuit in the PCM harness connector to a good ground. Is voltage less than 0.3 volt? If yes, go to next step. If no, go to step 11.
- Turn ignition off. Install fuse that supplies voltage to the cluster. Turn ignition on, with engine off. Connect a 3-amp fused jumper wire between the MIL control circuit in PCM harness connector and a good ground. Is the MIL illuminated? If yes, go to step 9. If no, go to next step.
- Remove the Instrument Panel Cluster (IPC). See appropriate ANALOG INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. Probe the ignition voltage circuit of the IPC harness connector with a test light connected to a good ground. Does test light illuminate? If yes, go to next step. If no, go to step 12.
- Test the MIL control circuit for an open or high resistance. Did you find and correct a condition? If yes, go to step 15. If no, go to next step.
- Test for an intermittent and for a poor connection at the IPC. Did you find and correct the condition? If yes, go to step 15. If no, go to step 13.
- Test for an intermittent and for a poor connection at the PCM. Did you find and correct the condition? If yes, go to step 15. If no, go to step 14.
- Repair short to ground in the ignition voltage circuit. After repairs, go to step 15.
- Repair short to voltage in the MIL control circuit. After repairs, go to step 15.
- Repair short to voltage in the MIL control circuit. After repairs, go to step 15.
- Repair or replace the IPC. See appropriate ANALOG INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. After repairs, go to step 15.
- Replace PCM. See REMOVAL & INSTALLATION - MONTANA, SILHOUETTE & VENTURE article. Reprogram PCM. See POWERTRAIN CONTROL MODULE under PROGRAMMING. After repairs, go to next step.
- Turn ignition off for 30 seconds. Does the vehicle operate correctly, without any MIL illumination and without any stored DTCs? If yes, system is okay. If no, go to step 2.