No Crank Reference Signal at PCM

Name of Code:
No Crank Reference Signal at PCM

When Monitored:
During engine cranking, with battery voltage less than 11.5 volts and manifold vacuum present.

Set Condition:
No signal from the crankshaft position (CKP) sensor during engine cranking or there is a camshaft position sensor signal without a CKP sensor signal.

Theory of Operation:
The crankshaft position sensor is a hall-effect type sensor used to detect crankshaft speed and position. The PCM supplies 8 volts and a sensor ground to the CKP sensor. The crankshaft position sensor signal circuit has a 5-volt pull-up from the PCM. The sensor signal is created by the notches in the crankshaft pulse ring passing under the sensor. When a notch is under the sensor, the signal remains at 5 volts. When there isn't a notch under the sensor, the signal drops to 0.3 volt.

Possible Causes:
- Open or shorted 8-volt supply circuit
- Open sensor ground
- Open or shorted signal circuit
- Excessive clearance between the sensor and crankshaft pulse ring
- Damaged crankshaft pulse ring
- Failed sensor
- Failed PCM
- Connector terminals
- Connector wires