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Home >> GMC >> 1997 >> Forward Control 4.3 W, L35, Automatic >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 10 (Engine Controls - Tests W/Codes - 6.5L Diesel (P Series)) >> Diagnostic Trouble Codes >> DTC P0335 - Crankshaft Position (CKP) Sensor Circuit Performance >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different variant/trim than selected.
  1. Perform Powertrain ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the BASIC TESTING article. Then go to next step.
  2. Install scan tool. Start and idle engine. Using scan tool, with throttle closed, observe CRANK REF MISSED display. If scan tool displays "8", go to step 4). If scan tool does not display "8", go to next step.
  3. DTC is intermittent. If no additional DTCs are set, see DIAGNOSTIC AIDS. If any additional DTCs are set, go to applicable DTC test.
  4. Turn ignition off. Disconnect CKP sensor connector. Turn ignition on, with engine off. Using DVOM, check voltage between 5-volt reference circuit of CKP sensor connector and ground. If voltage is 5 volts, go to next step. If voltage is not 5 volts, go to step 7).
  5. Using test light connected to battery voltage, probe ground circuit of CKP sensor connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 8).
  6. Reconnect CKP sensor connector. Using DVOM, backprobe CKP sensor signal circuit of PCM connector to ground. Crank engine. If voltage reading is 4 volts or greater, go to step 11). If voltage reading is less than 4 volts, go to step 10).
  7. Turn ignition off. Disconnect PCM harness connector. Check 5-volt reference circuit for open, short to ground, or short to sensor ground circuit. Repair as necessary. After repairs, go to step 14). If circuits are okay, go to step 9).
  8. Check for open or poor connections at sensor ground terminals of PCM. Repair as necessary. After repairs, go to step 14). If connections are okay, go to step 13).
  9. Check for poor connections at 5-volt reference terminals of PCM. Repair terminals as necessary. After repairs, go to step 14). If terminals are okay, go to step 13).
  10. Turn ignition off. Disconnect PCM harness connector. Check CKP sensor signal circuit for open, short to ground, or short to sensor ground circuit. Repair as necessary. After repairs, go to step 14). If circuits are okay, go to next step.
  11. Check for poor connections at CKP sensor terminals of PCM. Repair terminals as necessary. After repairs, go to step 14). If terminals are okay, go to next step.
  12. Replace CKP sensor. If CKP sensor is replaced, PCM must be programmed with new TDC offset. See the ADJUSTMENTS article. After replacing sensor, go to step 14).
  13. Replace PCM. After replacing PCM, 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 P0335. 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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