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Home >> GMC >> 1997 >> Forward Control 4.3 W, L35, Automatic >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 11 (Engine Controls - Tests W/Codes - 7.4L (P Series)) >> Diagnostic Trouble Codes >> DTC P0337 - Crankshaft Position Sensor Circuit Low Frequency >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different variant/trim than selected.
  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the F - BASIC TESTING - 7.4L article. After performing OBD system check, go to next step.
  2. Turn ignition off. Disconnect crankshaft position sensor connector. Turn ignition on, with engine off. Using test light, probe signal circuit of crankshaft position sensor connector (engine harness side) to ground. If test light illuminates, go to next step. If test light does not illuminate, go to step 8).
  3. Turn ignition off. Using test light, probe ground circuit of crankshaft position sensor connector (engine harness side) to battery voltage. If test light illuminates, go to next step. If test light does not illuminate, go to step 7).
  4. Disconnect Blue VCM connector. Using test light, probe ignition feed circuit of crankshaft position sensor connector (engine harness side) to battery voltage. If test light illuminates, go to step 10). If test light does not illuminate, go to next step.
  5. Reconnect Blue VCM harness connector. Install Gray jumper wires from Connector Test Kit (J 35616-A) between engine harness connector and crankshaft position sensor. Set DVOM to duty cycle position. Connect DVOM between signal circuit and ground circuit of crankshaft position sensor connector (engine harness side). Crank engine. If duty cycle is less than 30 percent, go to step 11). If duty cycle is not less than specified, go to next step.
  6. Check for poor connection at crankshaft position sensor. If connection is faulty, go to step 12).
  7. Check for open in ground circuit. If circuit is open, go to step 12). If a circuit is okay, go to step 9).
  8. Check for open or short to ground in ignition feed circuit. If a problem was found, go to step 12).
  9. Check for poor connection at VCM. If connection is faulty, go to step 12). If connection is okay, go to step 13).
  10. Repair short to ground in signal circuit. After repairs, go to step 14).
  11. Replace crankshaft position sensor. After replacing sensor, go to step 14).
  12. Repair circuit as necessary. After repairs, go to step 14).
  13. Replace VCM. Program replacement VCM using required equipment. After replacing VCM, go to next step.
  14. Using scan tool, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0337. Operate vehicle within the conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2).
  15. Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.
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