Crankshaft Position Sensor: Description and Operation

PURPOSE
The crankshaft position sensor is a hall-effect type sensor used to detect the crankshaft's speed and position.

OPERATION
The Powertrain Control Module (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 slots cut in the flywheel passing under the sensor. When a slot is under the sensor, the signal is high (5 volts). When the metal between the slots is under the sensor, the signal is low (0.3 volts).

NAME OF CODE:
No Crank Reference Signal at PCM

WHEN MONITORED:
With the ignition in either the start or run position and battery voltage between 4 and 15 volts.

SET CONDITION:
No crankshaft position (CKP) sensor signal is detected when engine vacuum is present or cam signals are present.

POSSIBLE CAUSES:
- Open or shorted 8-volt supply circuit
- Open sensor ground
- Open or shorted signal circuit
- Excessive clearance between the sensor and the flywheel
- Damaged flywheel
- Failed sensor
- Failed PCM
- Connector terminals
- Connector wires