Crankshaft Position Sensor: Description and Operation

DESCRIPTION

The Crankshaft Sensor provides a signal, through the Ignition Module, which the ECM uses as reference to calculate rpm and crankshaft position.

OPERATION
The Crank Sensor (and Combination Sensor on 3.OL) applications is mounted in a pedestal on the front of the engine near the harmonic balancer. 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. 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 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.

NOTICE
- Failure to have the correct clearance will damage the sensor.

The Crank Sensor is not adjustable for ignition timing but positioning of the interrupter ring is very important. A clearance of .025 of an inch is required on either side of the interrupter ring.