Diagnostic Procedures

2008 Chevrolet Chevy Express G2500, Van Cargo, 6.6 6SECTION Diagnostic Procedures
WARNING: This page is about a different car, the 2003 Pontiac Vibe. 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, perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
  2. Did you perform Transmission Fluid Checking Procedure? If yes, go to next step. If no, go to appropriate SERVICING article in AUTOMATIC TRANSMISSIONS.
  3. NOTE: Before clearing DTCs, use scan tool to record FAILURE RECORDS for reference. Using CLEAR DTC INFORMATION function will erase the stored failure records from PCM.
  4. Install scan tool. Turn ignition switch to RUN position, engine OFF. Record FAILURE RECORDS. Use scan tool to clear DTCs. Drive vehicle for at least 7 minutes. Using scan tool, observe TFT for rapid fluctuations in temperature. Record temperature at start and end of the trip. Was transmission fluid temperature 122-176°F (50-80°C)? If yes, go to step  9. If no, go to next step.
  5. Turn ignition switch to LOCK position. Disconnect PCM White 34-pin harness connector C1. Use a Digital Multi Meter (DMM) to measure resistance between PCM harness connector C1 terminals No. 28 and 30. Is resistance equal to 6.4 k/ohms at 50°F (10°C) and 0.2 k/ohms at 230°F (110°C)? If yes, go to step  9. If no, go to next step.
  6. Disconnect transmission Gray, 6-pin connector at the transmission. Use DMM to measure resistance between terminals No. 1 and 6 on transmission component connector. Is resistance equal to 6.4 k/ohms at 50°F (10°C) and 0.2 k/ohms at 230°F (110°C)? If yes, go to next step. If no, go to step  8.
  7. Disconnect PCM White 34-pin harness connector C1. Check transmission temperature sensor circuit between PCM and transmission connector for an open or high resistance. Did you find and correct the condition? If yes, go to step  12. If no, go to next step.
  8. Disconnect the PCM harness connector C1. Check the transmission temperature sensor signal circuit between PCM and transmission connector for a short to ground. Did you find and correct the condition? If yes, go to step  12. If no, go to step  10.
  9. Remove transmission oil pan. Check terminals and internal harness for damage. Replace TFT sensor if no damage exists. After repair, go to step  12.
  10. Install a known-good PCM. Use scan tool to clear DTCs. Check for DTCs. Does DTC P0710 reset? If yes, go to next step. If no, go to step  11.
  11. Check for a possible intermittent condition. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 1.8L VIBE article. After repair, go to step  12.
  12. Replace PCM. After repair, go to step  12.
  13. Turn ignition switch to LOCK position. Reconnect all connectors. Use scan tool to clear DTCs. Recheck for DTCs. Does the scan tool display any DTCs? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay at this time.
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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.