Diagnostic Procedure

2001 Chevrolet Chevy Express G2500, Van Cargo Extended, 5.7 R, L31/KL8SECTION Diagnostic Procedure
WARNING: This page is about a different car, the 2003 Pontiac Grand Prix, 2003 Chevrolet Malibu, and 2003 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLSΒ  under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check - engine controls, go to next step.
  2. Turn ignition switch to OFF position. Disconnect PCM harness connectors. Turn ignition switch to RUN position, engine off. Observe the MIL. Is the MIL illuminated? If yes, go to next step. If no, go to step Β 5.
  3. Check the MIL control circuit for a short to ground. Did you find and correct the condition? If yes, go to step Β 6. If no, go to next step.
  4. Replace IPC. Go to appropriate INSTRUMENT PANEL article in ACCESSORIES & EQUIPMENT. After replacing IPC, go to step Β 6.
  5. Replace PCM. See appropriate REMOVAL & INSTALLATION article. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULEΒ  under PROGRAMMING. After repair, go to next step.
  6. Turn ignition switch to OFF position for 30 seconds. Start the engine. Does the vehicle operate correctly without any unwanted MIL illumination, and without any stored DTCs? If yes, system is okay at this time. If no, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLSΒ .
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When to See a Mechanic

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

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