Camshaft Position Sensor

An angle pulse generator is used for the camshaft position sensor. This sensor differs in operation from either the hall or inductive type sensors used on previous systems.

The angle pulse generator consists of two windings (primary and secondary) that are connected together at one end, and a magnetic core. The primary winding is supplied with a 120 kHz AC signal. The magnetic coupling causes an induced voltage, at the same frequency, to be induced into the secondary winding. However the induced voltage has a slight phase shift due to the induction time delay.

The trigger wheel of the camshaft influences the magnet field of the sensor and causes the phase shift to increase as the disc of the wheel moves closer to the sensor. The MS41.1 Control Module sees this change in phase shift as the TDC compression input from the camshaft. When the disc passes by the sensor the phase shift moves closer again.

The MS41.1 Control Module uses the signal from the cam sensor to set up the triggering of the ignition coils through the firing order and for activation of fully sequential fuel injection.

There is no replacement value for the camshaft sensor. However, a faulty sensor input will cause the MS41.1 Control Module to activate double ignition for the coil firing and trigger the injectors in parallel injection.

The camshaft position sensor is monitored as part of the requirements for OBD II emission control. A faulty sensor input will be logged in the MS41.1 Control Module memory and if the OBD II criteria is satisfied, the Check Engine Lamp will illuminate.