Crankshaft Position Sensor: Description and Operation

CRANKSHAFT POSITION (CKP) SENSOR

The crankshaft position (CKP) sensor is a 3-wire sensor that provides a digital output signal. The wire circuits consist of an engine control module (ECM) supplied 5-Volt reference circuit, a low reference circuit between the CKP sensor and the ECM, and an output signal circuit from the CKP sensor to the ECM. The CKP sensor detects magnetic flux changes of the teeth and slots of the 58-tooth reluctor on the crankshaft. The CKP sensor provides an ON/OFF DC voltage of varying frequency, with 58 output pulses per each crankshaft revolution. The frequency of the CKP sensor output signal depends on the speed of the crankshaft. The CKP sensor sends a digital square wave signal, which represents an image of the teeth on the reluctor wheel, to the ECM. The 12 degree reference gap on the reluctor wheel is used to identify crankshaft position. The CKP information, along with the camshaft position (CMP) sensor information is used to determine the correct time and sequence for fuel injection, ignition spark events, detect cylinder misfire, and the camshaft to crankshaft relative position.