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 the crankshaft's 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