Crankshaft Position Sensor: Description and Operation

Ignition Control System:

Built into the distributor, the crank angle sensor consists of a photoelectric pick-up and rotor plate with light transmission slits. As the rotor plate turns, the slits alternately transmit and cut light read by the photoelectric pick-up unit. This generates pulses utilized by the ECM to calculate engine rpm and crankshaft position.

The ECM uses the input from the crank angle sensor, together with information from other sensors, to calculate and control the ignition timing advance curve.

Other sensors whose input is factored into ECM timing calculations include:

Throttle valve switch
Vehicle speed sensor
Coolant temperature sensor
Air flow sensor
Knock sensor