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Home >> Chevrolet >> 2001 >> Impala LS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics - 3.8L >> System Tests >> Mil Inoperative >> Diagnostic Procedure
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Diagnostic Procedure

  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. Inspect fuse that supplies voltage to MIL. If fuse is open, go to step  10. If fuse is okay, go to next step.
  3. Turn ignition off. Disconnect PCM. Turn ignition on, engine off. Connect a fused jumper wire (3-amp) between PCM connector C2 terminal No. 5 (Brown/White wire) and ground. See Fig 1. Observe MIL. If MIL is on, go to step  9. If MIL is off, go to next step.
  4. If fuse in jumper wire opened, go to step  11. If fuse in jumper wire did not open, go to next step.
  5. Remove IPC. Check Brown/White wire between PCM and IPC for open. If problem was found, repair as necessary. After repairs, go to step  14. If problem was not found, go to next step.
  6. Using a test light connected to ground, probe MIL battery voltage circuit at IPC harness connector. See IPC TERMINAL IDENTIFICATION  table for IPC connector terminal identification. If test light is on, go to step  8. If test light is off, go to next step.
  7. Repair open in MIL ignition voltage circuit. See MIL IGNITION VOLTAGE FEED  table for ignition voltage wire color. After repairs, go to step  14.
  8. Check IPC connector for poor connections. If problem was found, repair as necessary. After repairs, go to step  14. If problem was not found, go to step  12.
  9. Check PCM connectors for poor connections. If problem was found, repair as necessary. After repairs, go to step  14. If problem was not found, go to step  13.
  10. Repair short to ground in MIL ignition voltage circuit. See MIL IGNITION VOLTAGE FEED  table for ignition voltage wire color. 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. After repairs, go to step  14.
  13. Replace PCM. After repairs, go to next step.
  14. Operate system to verify repair.
IPC TERMINAL IDENTIFICATION

Model Terminal
Bonneville Connector C1, Terminal B1
Grand Prix Connector C1, Terminal "N"
Impala & Monte Carlo Terminal B2
LeSabre Connector C2, Terminal A3
Park Avenue Terminal A6
Regal Terminal B5
MIL IGNITION VOLTAGE FEED

Model MIL Ignition Feed Color
Bonneville, Grand Prix, Park Avenue & Regal Pink
Impala & Monte Carlo Purple
LeSabre Orange
Fig 1: Identifying PCM 80-Pin Harness Connector C1 (Blue) & C2 (Clear)
G00009284Courtesy of GENERAL MOTORS CORP.
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