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Home >> GMC >> 2000 >> Safari Van Cargo, RWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls Self-Diagnostics - 4.3L >> Diagnostic Tests >> DTC P0339: Crankshaft Position Sensor Circuit Intermittent >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
  2. If engine starts and runs, see DIAGNOSTIC AIDS . If engine does not start and run, go to next step.
  3. Disconnect CKP sensor harness connector. Connect a test light between engine ground and ignition feed circuit at CKP sensor. Turn ignition on, engine off. If test light illuminates, go to next step. If test light does not illuminate, go to step  6.
  4. Connect test light between CKP sensor harness connector ground and ignition feed circuits. If test light illuminates, go to next step. If test light does not illuminate, go to step  7.
  5. Turn ignition off. Install Gray jumper wires from Connector Tester Kit (J-35616-A) between CKP sensor and sensor harness connector. Connect DVOM (set to duty cycle) between CKP sensor signal and ground circuits. Crank engine. If displayed duty cycle is 40-60 percent, go to step  11. If duty cycle is not 40-60 percent, go to step  9.
  6. Repair open or short to ground in CKP sensor ignition feed circuit. After repairs, go to step  16.
  7. Check for open in CKP sensor harness connector ground circuit. If circuit is open, go to step  14. If circuit is okay, go to step  13.
  8. Check for open or short in 3X CKP sensor harness connector signal circuit. If circuit is faulty, go to step  14. If circuit is okay, go to step  11.
  9. Check CKP sensor and crankshaft reluctor wheel for damage. If a problem is found, go to next step. If no problem is found, go to step  12.
  10. Replace CKP sensor or crankshaft reluctor wheel. After replacing CKP sensor, reform CKP variation learn procedure. To perform learn procedure, enable CRANKSHAFT POSITION SYSTEM VARIATION LEARN PROCEDURE on scan tool. Apply and hold service brake. Slowly raise engine speed to 4000 RPM. Immediately release throttle when engine speed decreases. Turn ignition off for 15 seconds after learn procedure is completed successfully. After performing learn procedure, go to step  16.
  11. Check for poor connection at CKP sensor. If connection is faulty, go to step  14. If connection is okay, go to step  13.
  12. Ensure CKP sensor mounting surface is clean and free of debris. If CKP sensor mounting is okay, replace CKP sensor. After replacing sensor, perform CKP variation learn procedure. After performing variation learn procedure, go to step  16.
  13. Check for poor connection at VCM. If connection is faulty, go to next step. If connection is okay, go to step  15.
  14. Repair circuit as necessary. After repairs, go to step  16.
  15. Replace VCM. Program replacement VCM using required equipment. After replacing VCM, go to next step.
  16. Using scan tool, select DTC, CLEAR INFO function. Start engine and allow it to reach operating temperature. Using scan tool, select DTC, SPECIFIC function and enter this DTC. Operate vehicle within conditions required to set DTC. If scan tool indicates that this DTC RAN AND PASSED, go to next step. If scan tool does not indicate that this DTC RAN AND PASSED, repeat step  2.
  17. Using scan tool, select Read and Record INFO, REVIEW INFO function. Check if any undiagnosed DTCs are displayed. Diagnose affected DTCs. If no additional DTCs are displayed, system is okay.
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