No Crank Reference Signal At PCM (Non-OBD II)

Name of Code:
No Crank Reference Signal at PCM

When Monitored:
During engine cranking.

Set Condition:
No signal from the crank position sensor is present during engine cranking, and at least 3 cam position signals have occurred.

Theory of Operation:
The crank position sensor is a hall effect-type sensor used to detect the crankshaft speed and position. The PCM supplies 5 volts and a ground to power up the sensor. The PCM also supplies a 5-volt pull up voltage. The sensor signal is created by the slots 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 (0.03V).

Probable causes:
- Open or shorted 5-volt supply circuit
- Open sensor ground
- Open or shorted signal circuit
- Excessive clearance between tie sensor and flywheel or crankshaft
- Damaged flywheel
- Failed sensor
- Failed PCM
- Shorted VSS 5-volt supply circuit