No Crank Reference Signal at PCM

Name of Code:
No Crank Reference Signal at PCM

When Monitored:
During cranking with battery voltage between 4.0 and 11.6 volts and manifold vacuum present.

Set Condition:
No signal from the crank position sensor is present during engine cranking, or the cam position signal is present with no crank signal.

Theory of Operation:
The crank position sensor is a hall effect-type sensor used to detect the crankshaft speed and position. The PCM supplies 8-volts and a sensor ground to the CKP sensor. The crankshaft position sensor signal circuit has 5-volt pull-up voltage from the PCM. The sensor signal is created by the slots cut in the flywheel passing under the sensor. When a slot is under the sensor, the signal is high (5.0V). When the metal between the slots is under the sensor, the signal is low (0.3V).

Possible Causes:
- Open or shorted 8-volt supply circuit
- Open sensor ground
- Open or shorted signal circuit
- Excessive clearance between the sensor and flywheel
- Damaged flywheel
- Failed sensor
- Failed PCM