Mil Inoperative

2001 Chevrolet Chevy Express G2500, Van Cargo Extended, 5.7 R, L31/KL8SECTION Mil Inoperative
WARNING: This page is about a different variant/trim than selected.
NOTE: For circuit reference, see WIRING DIAGRAMS article.
  1. Perform powertrain diagnostic system check. See POWERTRAIN DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check, go to next step.
  2. Check 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, with engine off. Connect fused jumper wire (3-amp) between MIL control circuit and ground. Observe MIL. If MIL illuminates, go to step  9. If MIL does not illuminate, go to next step.
  4. Check fuse in jumper. If fuse is open, go to step  11. If fuse is okay, go to next step.
  5. Remove Instrument Panel Cluster (IPC). Check MIL control circuit for open between PCM and IPC. Repair as necessary. After repairs, go to step  14. If circuit is okay, go to next step.
  6. Using test light connected to ground, probe MIL ignition supply voltage circuit at IPC harness connector. If test light illuminates, go to step  8. If test light does not illuminate, go to next step.
  7. Repair open in MIL ignition supply voltage circuit. After repairs, go to step  14.
  8. Check IPC connector for poor connections. Repair as necessary. After repairs, go to step  14. If connections are okay, go to step  12.
  9. Check PCM connector for poor connections. Repair as necessary. After repairs, go to step  14. If problem connections are okay, go to step  13.
  10. Repair short to ground in MIL ignition supply voltage circuit. See WIRING DIAGRAMS article. After repairs, go to step  14.
  11. Repair short to voltage in MIL control circuit. After repairs, go to step  14.
  12. Replace IPC. See appropriate 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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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • You smell fuel, burning insulation, or see smoke.
  • Brakes feel soft, pull hard to one side, or make grinding noises.
  • The engine overheats, stalls repeatedly, or misfires under load.
  • You are missing required tools, torque specs, or safe lifting equipment.
  • You are not confident in the next step or safety outcome.