Crankshaft Position Sensor: Description and Operation

PURPOSE
The signal from the Crankshaft Position (CKP) Sensor is used to determine crankshaft angle, engine speed, and basic timing.

Powertrain Control Module (PCM) also uses the signal from the crankshaft position sensor combined with the input signal from the camshaft position sensor to properly synchronize fuel injection.

OPERATION
The crankshaft position sensor generates pulses that are input to the PCM. The PCM interprets the sensor input to determine the crankshaft position. The PCM then uses this position, along with other inputs, to determine injector sequence and ignition timing.

Crankshaft Position Sensor Operation:

The flywheel/drive plate has 8 single notches, spaced every 45 degrees, at its outer edge. The notches cause a pulse to be generated when they pass under the sensor. The pulses are the input to the PCM. For each engine revolution, there are 8 pulses.

If the PCM does not sense input from the crankshaft position sensor, PCM will deactivate the automatic shutdown relay and fuel pump relay, interrupting voltage to fuel pump, fuel injectors, and ignition coil, (no start condition).

CONSTRUCTION
The sensor is a hall effect device combined with an internal magnet. It is also sensitive to steel within a certain distance from it.