Crankshaft Position Sensor: Description and Operation

The crankshaft sensor is a magnetic switch that is used to provide the igntion module and the Electronic
Control Module (ECM) with the engine RPM and/or crankshaft position information much the same way as the High Energy Ignition (HEI) pick up coil.

The style of crankshaft sensor used and its function is determined by the engine application. Two types of sensors are presently being used: the magnetic type and the Hall Effect type.


These engines use a Hall Effect type crankshaft sensor. It provides only the crankshaft RPM signal to the ignition module. The sensor is mounted to the front side of the engine timing cover just behind the harmonic balancer.


The harmonic balancer has attached to the back side an interrupter ring which has three window slots positioned 120 degrees apart. The sensor mounts in a pedestal-type holder and, when properly adjusted, has an equal distance of .030" clearance on each side of the interrupter ring.