LEMON Manuals: Even more car manuals for everyone
Home >> GMC >> 2003 >> Safari Van Cargo, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 92 (Engine Controls - Self-Diagnostics - 6.6L Diesel) >> Diagnostic Tests >> DTC P0380: Glow Plug Circuit Performance (Fed) >> Diagnostic Procedures

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. Confirm that the glow plugs are commanded OFF with the scan tool. Does the scan tool display glow plug feedback signal voltage present all the time? If yes, go to step  9. If no, go to next step.
  3. Turn ON the ignition, with the engine OFF. Disconnect the glow plug relay. Probe the glow plug relay control circuit at the glow plug relay harness connector with a Digital Multimeter (DMM) connected to ground. Command the glow plug relay ON with a scan tool. Does the voltage measure near battery voltage? If yes, go to next step. If no, go to step  8.
  4. Turn ON the ignition, with the engine OFF. Probe the battery positive voltage circuit of the glow plug relay with a test lamp that is connected to a good ground. Does the test lamp illuminate? If yes, go to next step. If no, go to step  12.
  5. Probe the ground circuit of the glow plug relay with a test lamp connected to battery voltage. Does the test lamp illuminate? If yes, go to next step. If no, go to step  13.
  6. Reconnect the glow plug relay. Turn ON the ignition, with the engine OFF. Probe the glow plug signal circuit at the glow plug relay connector with a test lamp connected to a good ground. Command the glow plug relay ON and OFF with a scan tool. Does the test lamp illuminate when the scan tool commands the glow plugs ON? If yes, go to next step. If no, go to step  17.
  7. Turn OFF the ignition. Disconnect the ECM. Test the glow plug signal circuit for an open or short to ground. Did you find a problem? If yes, go to step  14. If no, go to step  18.
  8. Test the glow plug relay control circuit for an open or short to ground. If the glow plug relay control circuit is open or shorted to ground, repair as necessary. Did you find and correct the condition? If yes, go to step  21. If no, go to step  18.
  9. Disconnect the glow plug relay connector. Turn ON the ignition, with the engine OFF. Probe the glow plug relay control circuit with a test lamp connected to a good ground. Does the test lamp illuminate all of the time? If yes, go to next step. If no, go to step  11.
  10. Turn OFF the ignition. Disconnect the ECM. Turn ON the ignition. Probe the glow plug relay control circuit with a test lamp connected to a good ground. Does the test lamp illuminate? If yes, go to step  16. If no, go to step  20.
  11. Probe the glow plug signal circuit with a test lamp connected to a good ground. Does the test lamp illuminate? If yes, go to step  15. If no, go to step  19.
  12. Repair the open or short to ground in the battery positive voltage circuit to the glow plug relay. After repairs, go to step  21.
  13. Repair the open in the glow plug relay ground circuit. After repairs, go to step  21.
  14. Repair the open or short to ground in the glow plug signal circuit. After repairs, go to step  21.
  15. Repair the short to voltage in the glow plug signal circuit. After repairs, go to step  21.
  16. Repair the short to voltage in glow plug relay control circuit. After repairs, go to step  21.
  17. Check for poor connections at the glow plug relay. Repair as necessary. Did you find and correct the condition? If yes, go to step  21. If no, go to step  19.
  18. Check for poor connections at the ECM. Repair as necessary. Did you find and correct the condition? If yes, go to step  21. If no, go to step  20.
  19. Replace the glow plug relay. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to step  21.
  20. Replace the ECM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Reprogram ECM. See ENGINE CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  21. 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.
  22. 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.
scientia non olet · About LEMON Manuals