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HOMESERVICE MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 59 (ENGINE CONTROLS SELF-DIAGNOSTICS - 4.3L)DIAGNOSTIC TESTSDTC P0341: CAMSHAFT POSITION SENSOR CIRCUIT PERFORMANCEDIAGNOSTIC 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 6 other vehicles, including the 2002 GMC Sonoma, 2002 GMC Safari, 2002 GMC Jimmy, 2002 Chevrolet S10 Pickup, and 2002 Chevrolet Blazer. 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. Install a scan tool. Start the engine. Monitor the CAM signal input high to low and low to high transition parameter using the scan tool. Does the scan tool parameter increment? If yes, go to next step. If no, go to step  4.
  3. Observe the Freeze Frame/Failure Records data for this DTC. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running DTC or as close to the Freeze Frame/Failure Records data that you observed. Does the DTC fail this ignition cycle? If yes, go to next step. If no, see DIAGNOSTIC AIDS .
  4. Turn OFF the ignition. Disconnect the CMP sensor connector. Turn ON the ignition, with the engine OFF. Connect a Digital Multimeter (DMM) between the 12-volt reference circuit of the CMP sensor and a good ground. Does the voltage measure near battery voltage? If yes, go to step  6. If no, go to next step.
  5. Turn OFF the ignition. Disconnect the PCM. Test the 12-volt reference circuit of the CMP sensor for an open. Did you find and correct the condition? If yes, go to step  16. If no, go to step  12.
  6. Connect a test lamp to battery voltage. Touch the CMP sensor low reference circuit. Does the test lamp illuminate? If yes, go to step  8. If no, go to next step.
  7. Turn OFF the ignition. Disconnect the PCM. Test the low reference circuit of the CMP sensor for an open high resistance. Did you find and correct the condition? If yes, go to step  16. If no, go to step  12.
  8. Start the engine. Monitor the CAM signal high to low and low to high parameter on the scan tool. Connect a 5-amp fused jumper wire to battery voltage and momentarily touch the signal circuit 5 times for a duration of 1 second each. Does the cam signal high to low and low to high parameter change EACH time the signal circuit is touched? If yes, go to step  14. If no, go to next step.
  9. Did the fuse in the jumper wire open? If yes, go to step  11. If no, go to next step.
  10. Test the signal circuit of the CMP sensor for a short to voltage or an open or high resistance. Did you find and correct the condition? If yes, go to step  16. If no, go to step  12.
  11. Test the signal circuit of the CMP sensor for a short to ground. Did you find and correct the condition? If yes, go to step  16. If no, go to next step.
  12. Inspect for poor connections at the PCM. Did you find and correct the condition? If yes, go to step  16. If no, go to next step.
  13. Replace the PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Reprogram PCM. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to step  16.
  14. Inspect for poor connections at the CMP sensor. Did you find and correct the condition? If yes, go to step  16. If no, go to next step.
  15. Replace the CMP sensor. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to next step.
  16. 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.
  17. 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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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.