Camshaft Position Sensor: Description and Operation

Camshaft Sensor (Hall Effect):

PURPOSE
The camshaft position sensor (cylinder identification) monitors number six piston position.

Input from the sensor is used to set up the firing order of the coils and full sequential fuel injection. If the signal is faulty, the control unit switches to parallel injection and double ignition.

OPERATION
The intake camshaft has a light weight metal position disk attached behind the Variable Camshaft Control (VANOS) gear assembly. The disk is keyed to the camshaft and references TDC of the power stroke for cylinder #1.

The Hall Element in the sensor is supplied power and ground. The current flow through the hall element is the basis for the sensor's output signal to Digital Motor Electronic (DME).

As the camshaft turns the metal disk approaches the sensor tip. When the reference section of the metal disk is just under the tip of the sensor it creates a magnetic field with the permanent magnet in the sensor.

The attraction causes the magnetic field to penetrate through the hall element.

This effects the current flow in the element causing it to shift to the positive side, momentarily causing the monitored signal to go low.

This repetitive High/Low creates a square wave signal that DME uses for positive cylinder identification.