Crankshaft Position Sensor: Description and Operation

PURPOSE
The crankshaft position/speed sensor supplies the ignition ECU with information on crankshaft position and engine speed. From there the signal is sent to the fuel injection ECU where it is processed to determine the optimal air/fuel ratio to meet the specific demands of the engine.

LOCATION
The sensor is mounted behind the front crank pulley.

CONSTRUCTION
The sensor consists of a permanent magnet, a pole tip which concentrates a magnetic field at the end of the device and a coil. The magnet creates a magnetic field which varies in strength when a window is passing the tip.

OPERATION
Voltage is induced in the sensor when the windows on the crank pulley shutter pass the tip. This voltage signal is transmitted by three-core shielded wire to the ignition ECU.

The sensor supplies the ignition ECU with a unique electrical picture from which the ignition ECU can determine both the crankshaft position and speed.

SIGNAL
The frequency of the signal is used to determine the engine speed.