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Diagnostic Procedures

WARNING: This page is about a different car, the 2002 GMC Sierra, 2002 GMC Cab & Chassis Sierra, 2002 Chevrolet Silverado, and 2002 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
  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 Panel (IP) is operational. If the IP is completely inoperative, see appropriate ANALOG INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. Verify whether the MIL turns ON and OFF when commanded. Turn ON the ignition, with the engine OFF. Command the MIL ON and OFF using the scan tool. Repeat the commands as necessary. Does the MIL turn ON and OFF when commanded? If yes, go to next step. If no, go to step  4.
  3. Observe the Freeze Frame/Failure Records data for this DTC. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running DTC or as close to the Freeze Frame/Failure Records data that you observed. Does the DTC fail this ignition cycle? If yes, go to next step. If yes, see DIAGNOSTIC AIDS .
  4. Inspect the fuse that supplies battery positive voltage to the MIL. Is the fuse open? If yes, go to step  10. If no, go to next step.
  5. Turn OFF the ignition. Disconnect the ECM. Turn ON the ignition. Is the MIL OFF? If yes, go to next step. If no, go to step  11.
  6. Turn OFF the ignition. Remove the fuse that supplies voltage to the MIL. Turn ON the ignition, with the engine OFF. Connect a Digital Multimeter (DMM) from the MIL control circuit to a good ground. Does the voltage measure 0 V? If yes, go to next step. If no, go to step  12.
  7. Turn OFF the ignition. Reinstall the fuse that supplies voltage to the MIL. Turn ON the ignition, with the engine OFF. Probe the MIL control circuit in the ECM harness connector with a fused jumper wire connected to ground. Does the MIL illuminate? If yes, go to step  15. If no, go to next step.
  8. Turn OFF the ignition. Remove the Instrument Panel Cluster (IPC). See appropriate ANALOG INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. Probe the MIL battery positive voltage circuit at the IP harness connector with a test lamp connected to a good ground. Does the test lamp illuminate? If yes, go to next step. If no, go to step  13.
  9. Test the MIL control circuit for an open or high resistance and repair as necessary. Did you find and correct a condition? If yes, go to step  18. If no, go to step  14.
  10. Repair the short to ground in the battery positive voltage circuit. After repairs, go to step  18.
  11. Repair the short to ground in the MIL control circuit. After repairs, go to step  18.
  12. Repair the short to voltage on the MIL control circuit. After repairs, go to step  18.
  13. Repair the open in the MIL battery positive voltage circuit. After repairs, go to step  18.
  14. Inspect for poor connections at the IP and repair as necessary. Did you find and correct the condition? If yes, go to step  18. If no, go to step  16.
  15. Inspect for poor connections at the ECM and repair as necessary. Did you find and correct the condition? If yes, go to step  18. If no, go to step  17.
  16. Replace the IP. See appropriate ANALOG INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. After repairs, go to step  18.
  17. Replace the ECM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Reprogram ECM. See ENGINE CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  18. Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running DTC. Does the DTC run and pass? If yes, go to next step. If no, go to step  2.
  19. Observe the stored information, Capture Info with a scan tool. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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