Crankshaft Position Sensor: Description and Operation

Crankshaft Position Sensor Operation 3.9L:

LOCATION

The sensor is located on the bellhousing of the transmission.


PURPOSE

The signal from the [1][2]Crankshaft Position Sensor is used to determine crankshaft angle, engine speed, and basic timing.

The engine controller also uses the signal from the [1][2]Crankshaft Position Sensor combined with the input signal from the camshaft position sensor to properly synchronize injection.


OPERATION

The [1][2]crankshaft position sensor is a hall effect switch that detects notches on the flywheel/drive plate.

The notches cause a pulse to be generated when they pass through the switch. The pulses are input to the engine controller. For each engine revolution there are 3 groups of 2 pulses and 3 groups of 1 pulse generated.

If engine controller does not sense input from the [1][2]crankshaft position sensor, engine controller will deactivate ASD and fuel pump relay, interrupting voltage to fuel pump, fuel injectors, and ignition coil, causing a no start condition.