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DTC P0320: No Crank Reference Signal At Pcm: Testing

  1. With the DRBIII®, read the Current Crankshaft Position (CKP) Sensor State while cranking the engine. Does the DRBIII® display Current CKP State Present while cranking the engine? If yes, go to next step. If no, go to step  6.
  2. Turn the ignition off. With the DRBIII® lab scope probe and the Miller Special Tool (6801), backprobe the CKP Signal circuit in the PCM C1 harness connector Turn the ignition on. Do not start or crank the engine. Observe the lab scope screen. Look for any pulses generated by the CKP Sensor. Did the CKP Sensor generate any pulses? If yes, replace the Crankshaft Position Sensor. If no, go to next step.
  3. Turn the ignition off. With the DRBIII® lab scope probe and the Miller Special Tool (6801), backprobe the Camshaft Position (CMP) Sensor Signal circuit in the PCM C1 harness connector. Turn the ignition on. Do not start or crank the engine. Observe the lab scope screen. Look for any pulses generated by the CMP Sensor. Did the CMP Sensor generate any pulses? If yes, replace the Camshaft Position Sensor. If no, go to next step.
    4. WARNING: When the engine is operating, do not stand in a direct line with the fan. Do not put your hands near the pulleys, belts or fan. Do not wear loose clothing.
  4. Turn the ignition off. With the DRBIII® lab scope probe and the Miller Special Tool (6801), backprobe the CKP Signal circuit in the PCM C1 harness connector. Start the engine. Observe the lab scope screen while wiggling the wiring harness and connectors. Were there any irregularities in the lab scope pattern? If yes, check the harness connectors carefully. If okay, replace the Crankshaft Position Sensor. If no, go to next step.
    5. WARNING: When the engine is operating, do not stand in a direct line with the fan. Do not put your hands near the pulleys, belts or fan. Do not wear loose clothing.
  5. The conditions that set the DTC are not present at this time. The following may help in identifying the intermittent condition. With the engine running at normal operating temperature, monitor the DRBIII® parameters related to the DTC while wiggling the wiring harness. Look for parameter values to change and/or a DTC to set. Review the DRBIII® Freeze Frame information. If possible try to duplicate the conditions under which the DTC was set. Refer to any Technical Service Bulletins (TSB) that may apply. Visually inspect the related wiring harness. Look for any chafed, pierced, pinched, or partially broken wires. Visually inspect the related wiring harness connectors. Look for broken, bent, pushed out, or corroded terminals. Were any of the above conditions present? If yes, repair as necessary. If no, test is complete.
  6. Turn the ignition off. Disconnect the CKP Sensor harness connector. Turn the ignition on. Measure the voltage of the 8-Volt Supply circuit in the CKP Sensor harness connector. Is the voltage between 7.5 and 8.5 volts? If yes, go to next step. If no, go to step  15.
  7. Measure the voltage of the CKP Sensor Signal circuit in the CKP Sensor harness connector. Is the voltage between 4.5 and 5.0 volts? If yes, go to next step. If no, go to step  10.
  8. Turn the ignition off. Disconnect the PCM C2 harness connector. Measure the resistance of the Sensor Ground circuit between the CKP Sensor harness connector and the PCM C2 harness connector. Is the resistance below 5.0 ohms? If yes, go to next step. If no, repair the Sensor Ground circuit for an open.
  9. Inspect the slots on flywheel for damage. If a problem is found, repair as necessary. If no problem is found, replace CKP sensor.
  10. Turn the ignition off. Ensure CKP Sensor is disconnected. Disconnect the PCM C1 harness connector. Measure the resistance of the CKP Sensor Signal circuit in the CKP Sensor harness connector to ground. Is the resistance below 5.0 ohms? If yes, repair the CKP Sensor Signal circuit for a short to ground. If no, go to next step.
  11. Measure the resistance of the CKP Sensor Signal circuit from the CKP Sensor harness connector to the PCM C1 harness connector. Is the resistance below 5.0 ohms? If yes, go to next step. If no, repair the CKP Sensor Signal circuit for an open.
  12. Ensure the ignition is off. Reconnect PCM connector. Turn the ignition on. Measure the voltage of the CKP Sensor Signal circuit at the CKP Sensor harness connector. Is the voltage above 5.0 volts? If yes, repair the CKP Sensor Signal circuit for a short to battery voltage. If no, go to next step.
  13. Turn the ignition off. Disconnect PCM connectors. Measure the resistance between the CKP Sensor Signal circuit and the 8-Volt Supply circuit in the CKP Sensor harness connector. Is the resistance below 5.0 ohms? If yes, repair the CKP Sensor Signal circuit shorted to the 8-Volt Supply circuit. If no, go to next step.
  14. There are no possible causes remaining, replace PCM. Program the new PCM. See PROGRAMMING .
  15. Turn the ignition off. Ensure the CKP Sensor is disconnected. Disconnect the PCM harness connectors. Measure the resistance of the 8-Volt Supply circuit in the CKP Sensor harness connector to ground. Is the resistance below 100 ohms? If yes, repair the 8-Volt Supply circuit for a short to ground. If no, go to next step.
  16. Measure the resistance of the 8-Volt Supply circuit between the CKP Sensor harness connector and the PCM harness connector. Is the resistance below 5.0 ohms? If yes, go to next step. If no, repair the 8-Volt Supply circuit for an open.
  17. Turn the ignition off. Reconnect PCM connectors. Turn the ignition on. Measure the voltage of the 8-Volt Supply circuit in the CKP Sensor harness connector. Is the voltage above 8.5 volts? If yes, repair the 8-Volt Supply circuit for a short to battery voltage. If no, go to next step.
  18. There are no possible causes remaining, replace PCM. Program the new PCM. See PROGRAMMING .
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