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Mil Inoperative

NOTE: For circuit reference, see appropriate WIRING DIAGRAM article.
Fig 1: PCM Harness Connector Terminal Identification
G00057682Courtesy of GENERAL MOTORS CORP.
  1. Perform powertrain diagnostic system check. See POWERTRAIN DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing powertrain diagnostic system check, go to next step.
  2. On "L" and "M" Series, check RADIO BATT fuse. On "S" and "T" Series, check GAUGES fuse. Fuse on both models is located in passenger compartment fuse/relay block. If fuse is open, go to step  10. If fuse is okay, go to next step.
  3. Turn ignition off. Disconnect PCM harness connector. Turn ignition on, with engine off. Connect fused jumper wire (3-amp) between ground and PCM harness connector C2 terminal No. 46 (Brown/White wire). See Fig 1. Observe MIL. If MIL illuminates, go to step  9. If MIL does not illuminate, go to next step.
  4. Turn ignition off. Check fuse in jumper wire. If fuse is open, go to step  11. If fuse is okay, go to next step.
  5. Remove Instrument Panel Cluster (IPC) harness connector. Check for open in Brown/White wire between IPC harness connector terminal A1 ("L" and "M" Series) or A11 ("S" and "T" Series) and PCM harness connector C2 terminal No. 46. Repair as necessary. After repairs, go to step  14. If circuit is okay, go to next step.
  6. Turn ignition on, with engine off. Using test light connected to ground, probe IPC harness connector terminal B9 (Orange wire) on "L" and "M" Series or terminal A7 (Pink wire) on "S" and "T" Series. If test light illuminates, go to step  8. If test light does not illuminate, go to next step.
  7. Turn ignition off. Repair open Orange or Pink wire between IPC and fuse block. After repairs, go to step  14.
  8. Turn ignition off. Check IPC harness connector for poor connections. Repair as necessary. After repairs, go to step  14. If connections are okay, go to step  12.
  9. Turn ignition off. Check PCM harness connector for poor connections. Repair as necessary. After repairs, go to step  14. If connections are okay, go to step  13.
  10. Repair short to ground in Orange or Pink wire between fuse block and IPC harness connector terminal. See WIRING DIAGRAMS article. After repairs, go to step  14.
  11. Repair short to voltage in Brown/White wire between IPC and PCM. After repairs, go to step  14.
  12. Replace IPC assembly. See appropriate ANALOG INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. After repairs, go to step  14.
  13. Replace PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  14. Operate system to verify repair.
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