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HOMESERVICE MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 78 (ENGINE CONTROL SYSTEM SELF-DIAGNOSTICS - 3.8L)DIAGNOSTIC TESTSDTC P0336: CRANKSHAFT POSITION SENSOR CIRCUITDIAGNOSTIC PROCEDURES
1999 GMC Forward Control 5.7 R, Automatic

Diagnostic Procedures

1999 GMC Forward Control 5.7 R, AutomaticSECTION Diagnostic Procedures
WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2002 Pontiac Grand Prix, 2002 Pontiac Bonneville, 2002 Chevrolet Monte Carlo, 2002 Chevrolet Impala, and 2002 Buick Regal. 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 CONTROLS  under SELF-DIAGNOSTIC SYSTEM. After performing Diagnostic System Check - Engine Controls, go to next step.
  2. Attempt to start engine. Does the engine start? If yes, go to next step. If no, go to step  4.
  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 DIAGNOSTIC AIDS .
  4. Test for the following conditions in the medium resolution engine speed signal circuit between the Ignition Control Module (ICM) and the Powertrain Control Module (PCM):
    • An open.
    • A short to voltage.
    • A short to ground.

    Repair as necessary. Did you find and correct the condition? If yes, go to step  12. If no, go to next step.

  5. Test for an open in the CKP sensor 2 signal circuit. Did you find and correct the condition? If yes, go to step  7. If no, go to next step.
  6. Turn off the ignition. Disconnect the crank sensor. Connect a test lamp to a good ground. Connect a DMM between the medium resolution engine speed signal circuit at the PCM connector and a good ground. Turn on the ignition, with the engine off. Repeatedly touch the test lamp to the CKP sensor 1 signal circuit at the crank sensor connector while observing the DMM. Does the measured voltage change? If yes, go to step  8. If no, go to next step.
  7. Test for a short to voltage or for poor connections at the ICM. Did you find and correct the condition? If yes, go to step  12. If no, go to step  10.
  8. Inspect for the following conditions:
    • Incorrect harness routing near secondary ignition components.
    • Ignition coil arcing to the wiring harness or to the ignition control module.
    • The ignition coils for cracks, carbon tracking, or other signs of damage.
    • Spark plug wires arcing.

    Did you find and correct the condition? If yes, go to step  12. If no, go to next step.

  9. Inspect for poor connections at the PCM. Did you find and correct the condition? If yes, go to step  12. If no, go to step  11.
  10. Replace ICM. After repairs, go to step  12.
  11. Replace PCM. Program replacement PCM. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  12. 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.
  13. 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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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.