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Diagnostic Procedure

WARNING: This page is about a different car, the 2003 GMC Envoy XL and 2003 Chevrolet TrailBlazer. 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. Turn OFF the ignition. Disconnect the PCM. See COMPONENT LOCATIONS . Turn ON the ignition, with the engine OFF. Observe the MIL. Is the MIL illuminated? If yes, go to next step. If no, go to step  5.
  3. Remove the Instrument Panel Cluster (IPC). See appropriate ANALOG INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. Test the MIL control circuit for a short to ground between the PCM and the IPC. Did you find and correct the condition? If yes, go to step  6. If no, go to next step.
  4. Repair or replace the IPC. See appropriate ANALOG INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. After repairs, go to step  6.
  5. Replace the PCM. See POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in REMOVAL & INSTALLATION - BRAVADA, ENVOY, ENVOY XL, TRAILBLAZER & TRAILBLAZER EXT article. Reprogram PCM. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  6. Turn OFF the ignition for 30 seconds. Does the vehicle operate correctly, without any MIL illumination and without any stored DTCs? If yes, system is okay. If no, see DIAGNOSTIC TROUBLE CODE DEFINITIONS .
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