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Home >> GMC >> 2003 >> Safari Van Cargo, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 105 (Engine Control System Self-Diagnostics - 3.8L) >> Diagnostic Tests >> DTC P1374: Crankshaft Position High-To-Low Resolution Frequency Correlation >> Diagnostic Procedures

Diagnostic Procedures

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  1. Perform Diagnostic System Check - Engine Controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS . After performing Diagnostic System Check - Engine Controls, go to next step.
  2. Attempt to start engine. Does the engine start and run? If yes, go to next step. If no, see NO-START DIAGNOSIS in appropriate BASIC DIAGNOSTIC PROCEDURES article.
  3. Observe FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within Conditions for Running DTC or as close to FREEZE FRAME/FAILURE RECORDS data as possible. Does the DTC fail this ignition cycle? If yes, go to next step. If no, see INTERMITTENT CONDITIONS  under SELF-DIAGNOSTIC SYSTEM.
  4. Turn ignition off. Disconnect ICM connector. Turn on the ignition, with the engine off. Connect a test lamp to battery voltage. Observe the engine speed parameter on the scan tool. Repeatedly touch the test lamp quickly to the low resolution engine speed signal circuit at the ICM harness connector. Is an engine speed displayed? If yes, go to step  8. If no, go to next step.
  5. Inspect for the following conditions:
    • The low resolution engine speed signal circuit open.
    • The low resolution engine speed signal circuit shorted to ground.
    • The low resolution engine speed signal circuit shorted to voltage.

    If a condition is found, repair as necessary. Did you find and correct the condition? If yes, go to step  11. If no, go to next step.

  6. Test for an intermittent and for a poor connection at the PCM. Did you find and correct the condition? If yes, go to step  11. If no, go to next step.
  7. Check for the following conditions:
    • Incorrect harness routing near secondary ignition components.
    • Ignition coil arcing to wiring harness or to ignition control module.
    • Ignition coils for cracks, carbon tracking, or other signs of damage. If carbon tracking is detected on any component, replace that component and components mate.
    • Secondary ignition wires arcing to wiring harness.

    Did you find and correct the condition? If yes, go to step  11. If no, go to step  10.

  8. Test for an intermittent and for a poor connection at the ICM. Did you find and correct the condition? If yes, go to step  11. If no, go to next step.
  9. Replace ICM. After repairs, go to step  11.
  10. Replace PCM. Program replacement PCM. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  11. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within Conditions for Running DTC. Does DTC run and pass? If yes, go to next step. If no, go to step  2.
  12. Using scan tool, observe stored information. Does scan tool displays any DTCs that have not been diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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