Crankshaft Angle Sensor

The crankshaft angle sensor monitors engine speed and piston position. The crankshaft angle sensor, which is built into the distributor, has a rotor plate and a wave-forming circuit. The rotor plate has 360 small outer slits (one degree apart) to determine crankshaft angle, and 4 (4-cylinder) or 6 (V6) larger inner signal slits (90 (4-cylinder) or 60 (V6) degrees apart) to determine engine speed. See Figure . The signal slit for the No. 1 cylinder is the largest of the 4 (4-cylinder) or 6 (V6) inner signal slits to allow ECU to determine TDC for No. 1 cylinder.

When the signal rotor plate passes the space between the Light Emitting Diode (LED) and photo diode, the slits in the signal rotor plate alternately cut the light from LED to the photo diode. This causes a pulsating voltage, which is converted into an on-off pulse by the wave-forming circuit and sent to the ECU. ECU uses this signal to control fuel injection, ignition timing and other functions.