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Home >> GMC >> 2003 >> Jimmy 4D Utility, AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics - 4.3L >> System Tests >> Malfunction Indicator Light Inoperative >> Diagnostic Procedure

Diagnostic Procedure

  1. 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.
  2. Verify whether the instrument cluster is operational. If instrument panel is completely inoperative, diagnose instrument cluster. See appropriate ANALOG INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. If instrument panel is okay, command the MIL ON and OFF with scan tool. Does the MIL turn ON and OFF when commanded with a scan tool? If yes, problem is intermittent. Refer to INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 4.3L ASTRO, BLAZER, JIMMY CANADIAN, SAFARI, SONOMA & S10 PICKUP article. If no, go to next step.
  3. Inspect fuse that supplies ignition voltage to the cluster. Is fuse open? If yes, go to step  10. If no, go to next step.
  4. Turn ignition off. Remove fuse that supplies voltage to the cluster. Disconnect the PCM. 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.
  5. 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 the PCM harness connector and a good ground. Is MIL illuminated? If yes, go to step  9. If no, go to next step.
  6. Turn ignition off. Remove the Instrument Panel Cluster (IPC). Refer to 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 the test light illuminate? If yes, go to next step. If no, go to step  12.
  7. 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.
  8. 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.
  9. 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.
  10. Repair short to ground in the battery positive voltage circuit. After repairs, go to step  15.
  11. Repair short to voltage in the MIL control circuit. After repairs, go to step  15.
  12. Repair open in the ignition voltage circuit. After repairs, go to step  15.
  13. Repair or replace the IPC. See appropriate ANALOG INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. After repairs, go to step  15.
  14. Replace PCM. See appropriate REMOVAL & INSTALLATION article. Reprogram PCM. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  15. Turn ignition off for 30 seconds. Start engine. Does the vehicle operate correctly, without any MIL illumination and without any stored DTCs? If yes, system is okay. If no, see DIAGNOSTIC TROUBLE CODE DEFINITIONS .
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