Crankshaft Position Sensor: Description and Operation

Crankshaft Position Sensor:

The crank angle sensor, located in the distributor, monitors engine speed and piston position.
It has a rotor plate and a wave forming circuit. The rotor plate has 360 slits for 1° signals and 4 slits for 180° signals. Photo diodes and light emitting diodes (LED's) are used for the wave forming circuit.
When the rotor passes between the photo diodes and LED's the slits in the rotor plate cut the light being transmitted to the photo diode from the LED. This generates pulses which are changed into ON/OFF signals by the wave forming circuit. The ECU interprets these signals to calculate engine rpm and cylinder position.