Crankshaft Position Sensor: Description and Operation

PURPOSE

The engine rpm sensor produces an output pulse to the ECU 4 times per distributor rotation. The ECU uses this signal to determine engine speed and relative TDC for each cylinder.

LOCATION

The sensor is mounted inside the distributor.

CONSTRUCTION

The sensor is made up of a pick-up coil and a rotor with 4 teeth, spaced a 90° intervals. The are placed in relation to TDC at each cylinder.

OPERATION

Whenever the engine is rotating, a sine-wave signal is returned to the ECU. The pulses occurs at 90° intervals. As engine speed increases the frequency of the signal increases as well. When coupled with the signal of the crankshaft angle sensor, exact piston position can be determined by the ECU.