Crankshaft Position Sensor: Description and Operation

CIRCUIT DESCRIPTION
The crank position sensor is a hall effect-type sensor used to detect the crankshaft speed and position.
The Powertrain Control Module (PCM) supplies 8 volts to the crankshaft position sensor on circuit K25. Circuit K25 connects to cavity 7 of the PCM to power-up the sensor. Sensor ground is provided by the PCM cavity 4. The PCM also supplies a 5-volt pull-up voltage to the sensor cavity 24. 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 volts). When the metal between the slot is under the sensor, the signal is low (0.3 volts).

The PCM receives the crankshaft position sensor signal on circuit K27. Circuit K27 connects to cavity 24 of the PCM.

The PCM provides a ground for the crankshaft position sensor (circuit K27) through circuit K4. Circuit K4 connects to cavity 4 of the PCM.

PURPOSE
The signal from the Crankshaft Position (CKP) Sensor is used to determine crankshaft angle, engine speed, and basic timing.

Powertrain Control Module (PCM) also uses the signal from the CKP sensor combined with the input signal from the camshaft position sensor to properly synchronize injection.

The sensor is located on the bellhousing of the transmission.

Crankshaft Position (CKP) Sensor Operation:

OPERATION
The crankshaft position sensor is a hall effect switch that detect notches on a pulse ring mounted to the crankshaft.

The notches cause a pulse to be generated when they pass under the sensor. The pulses are input to the PCM. For each engine revolution there are 3 groups of 4 pulses generated.

The trailing edge of the fourth notch is 4 degrees before top dead center of its corresponding cylinder.

NOTE: If PCM does not sense input from the crankshaft position sensor, PCM will deactivate Automatic Shutdown (ASD) and fuel pump relays, interrupting voltage to fuel pump, fuel injectors, and ignition coil, causing a no start condition.