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Home >> Pontiac >> 1996 >> Trans Sport >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Basic Testing >> On-Board Diagnostic (OBD) System Check >> A-1, Malfunction Indicator Light (Mil)

A-1, Malfunction Indicator Light (Mil)

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  . After performing OBD system check, go to next step.
  2. Attempt to start engine. If engine starts, go to next step. If engine does not start, go to step 6).
  3. Check instrument cluster ignition feed circuit fuse. See Figure . If fuse is okay, go to next step. If fuse is faulty, go to step 15).
  4. Turn ignition on. Using test light connected to ground, probe ignition feed circuit at cluster connector. See WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 12).
  5. Turn ignition off. Disconnect PCM harness connector. Turn ignition on. Using a fused jumper wire, jumper MIL driver circuit (Brown/White wire) at PCM to ground. See Figure . If MIL illuminates, go to step 10). If MIL does not illuminate, go to step 11).
  6. Check PCM ignition feed and battery feed fuses. If both fuses are okay, go to step 7). If fuse(s) are faulty, go to step 14).
  7. Turn ignition off. Disconnect PCM harness connector. Using a test light connected to ground, probe ignition feed circuit at PCM harness connector terminal (Pink wire). See Figure . If test light illuminates, go to next step. If test light does not illuminate, go to step 13).
  8. With test light connected to ground, probe battery feed circuit (Red wire) at PCM harness connector terminal. If test light illuminates, go to step 9). If test light does not illuminate, go to step 13).
  9. Check for faulty or poor PCM ground connection. Repair as necessary. After repairs, do ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  . If circuit is okay, go to step 10).
  10. Check for poor PCM connection. Repair as necessary. After repairs, perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  . If PCM connection is okay, go to step 16).
  11. Check for open MIL driver circuit (Brown/White wire). See Figure . Repair as necessary. After repairs, perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  . If circuit is okay, go to step 17).
  12. Repair open in ignition feed circuit to instrument cluster indicators. See WIRING DIAGRAMS article. Repair as necessary. After repairs, do ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  .
  13. Locate and repair open in PCM battery feed circuit or PCM ignition feed circuit. See Figure . After repairs, perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  .
  14. Locate and repair short to ground in PCM ignition feed circuit or PCM battery feed circuit. After repairs, perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  .
  15. Locate and repair short to ground in feed circuit to instrument cluster indicators. After repairs, perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  .
  16. Replace PCM. Perform PCM relearn procedures. After repairs, perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  .
  17. Check for poor connection at MIL driver circuit in instrument panel connector. Repair as necessary. After repairs, perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  . If MIL driver circuit connections are okay, diagnose instrument panel. See INSTRUMENT PANEL article in the ACCESSORIES/SAFETY EQUIPMENT section.
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