No Crank Reference Signal at PCM

Name of code: No Crank Reference Signal At PCM

When monitored: With the 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 crankshaft speed and position. The PCM supplies 8 volts from cavity 7 to power up the sensor. Sensor ground is provided through PCM cavity 4. The PCM also supplies a 5-volt pull-up voltage to the sensor from cavity 24. The sensor signal is created when slots cut in the vibration damper pass under the sensor. When a slot is under the sensor, the signal is high (5v). 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 damper
- Failed sensor
- PCM failure