Crankshaft Position Sensor: Description and Operation

PURPOSE
The Crankshaft Position (CKP) sensor provides a signal through the Ignition Control Module (ICM) which the Powertrain Control Module (PCM) uses as reference to calculate RPM and crankshaft position.

OPERATION
The dual crankshaft position sensor contains two Hall-effect switches with one shared magnet mounted between them. The magnet and each Hall-effect switch are separated by an air gap.

The Hall-effect switch reacts like a solid state switch, grounding low current signal voltage when a magnetic field is present. When the magnetic field is shielded from the switch by a piece of steel placed in the air gap between the magnet and the switch, the signal voltage is not grounded. If the piece of steel (interrupter) is repeatedly moved in and out of the air gap, the signal voltage will appear to go "ON-OFF-ON-OFF-ON-OFF."

Compared to a conventional mechanical distributor, this "ON-OFF" signal is similar to the signal a set of breaker points in the distributor would generate as the distributor shaft turned and the points opened and closed.