Crankshaft Position Sensor: Description and Operation

Crankshaft Position Sensor:

DESCRIPTION
The crank sensor is mounted in a pedestal on the front of the engine near the harmonic balaner. The sensor is a "hall-effect" switch which depends on a metal interrupter ring, mounted on the balancer to activate it. Windows in the interrupter activate the "hall-effect" switch as they provide a path for the magnetic field between the switch's transducer and it's magnet.

OPERATION
When the "hall-effect" switch is activated, it grounds the signal line to the C3I module, pulling the crank signal line's applied voltage low which is interpreted as a crank signal. Because of the way the signal by the crank sensor is created, the signal circuit is always either at a high or low voltage (square wave signal) and three signal pulses are created during each crankshaft revolution. This signal issued by the C3I module to create a reference signal which is also a "square wave" signal similar to the crank signal.

The reference signal is used to calculate engine rpm and crankshaft position by the Electronic Control Module (ECM). A misadjusted sensor or bent interrupter ring could cause rubbing of the sensor resulting in potential driveability problems such as rough idle, poor performance or a no start condition. Failure to have the correct clearance will damage the sensor.