Crankshaft Position Sensor: Description and Operation

Crank Angle Sensor:

PURPOSE
The crank angle sensor is a photoelectric sensing mechanism. It provides a crank angle signal and cylinder identification signal to the ECU. This information is used for proper fuel and ignition timing.

LOCATION
The sensor is built into the distributor housing.

CONSTRUCTION
The sensor consists of a slotted rotor plate and two LED/photo diode pairs. On the outer ring of the rotor plate, their are 4 slits positioned 90° apart. This portion of the sensor reports cylinder TDC to the ECU.

Inside the outer sensor ring, are 360 slots spaced at 1° increments. This portion of the sensor is used to determine actual piston position.

OPERATION
A signal is generated by the sensor whenever the engine is rotating. By combining the 90° & 1° signals, the ECU is able to compute the position of each piston.