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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 P0370 & P0374: Timing Reference High Resolution >> 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. Crank the engine. Use the scan tool to observe the Specific DTC information for the DTC that was set. Does the scan tool display Last Test Failed? If yes, go to next step. If no, see INTERMITTENT CONDITIONS  under SELF-DIAGNOSTIC SYSTEM.
    3. NOTE: Use the proper terminal from J 35616-A Connector Test Adapter Kit.
  3. Turn OFF the ignition. Disconnect the Fuel Injection Control Module (FICM) harness connector containing the engine speed signal circuit. Measure the voltage from the engine speed signal circuit at the FICM harness connector to a good ground using an adapter terminal and a Digital Multimeter (DMM). Crank the engine. Does the voltage measure 4-5 V? If yes, go to next step. If no, go to step  5.
  4. With the DMM still connected, measure the current from the engine speed signal circuit to a good ground. Does the current measure less than 10 mA? If yes, go to step  10. If no, go to next step.
  5. Does the voltage measure above 4-5 V? If yes, go to step  7. If no, go to step  8.
  6. Repair the short to reference voltage on the engine speed signal circuit. After repairs, go to step  13.
  7. Test for a short to battery voltage, ignition voltage, or either 5-volt reference on the engine speed signal circuit. Repair as necessary. Did you find and correct the condition? If yes, go to step  13. If no, go to step  11.
  8. Test the engine speed signal circuit for an open or a short to ground. Repair as necessary. Did you find and correct the condition? If yes, go to step  13. If no, go to step  11.
  9. Inspect for poor connections at the FICM. Repair as necessary. Did you find and correct the condition? If yes, go to step  13. If no, go to next step.
  10. Replace the fuel injection control module. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to step  13.
  11. Inspect for poor connections at the ECM. Repair as necessary. Did you find and correct the condition? If yes, go to step  13. If no, go to next step.
  12. Replace the ECM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Reprogram ECM. See ENGINE CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  13. 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.
  14. 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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