No Crank Reference Signal at PCM

NAME OF CODE
No Crank Reference Signal at PCM

WHEN MONITORED
With ignition ON.

SET CONDITION
No signal is present at the powertrain control module (PCM) when the vehicle speed exceeds 25 MPH.

THEORY OF OPERATION
The crank position sensor is a hall effect-type sensor used to detect the crankshaft speed and position. The Powertrain Control Module 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 when slots in the vibration damper pass 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).

POSSIBLE CAUSES
- Open or shorted 5-volt supply circuit
- Open sensor ground
- Open or shorted signal circuit
- Excessive clearance between the sensor and flywheel or crankshaft
- Damaged flywheel
- Failed sensor
- Failed PCM
- Shorted VSS 5-volt supply circuit