Camshaft Position Sensor: Description and Operation

Camshaft Position Sensor:

PURPOSE
Sends engine speed and position information to the ECM.

LOCATION
Built into the distributor.

OPERATION
Engine speed is calculated by the engine control module (ECM) from the ignition reference pulses it receives from the camshaft position sensor. The ECM will keep this value close to the desired idle under various engine loads with the engine idling.

CONSTRUCTION
The CMP sensor located in the distributor consists of the signal generator (hall element and magnet) and signal rotor. As the signal rotor turns, it causes the magnetic flux from the magnet to be applied to the hall element intermittently. The hall element generates the voltage in proportion with the magnetic flux as shown in figure. This voltage is wave-shaped into the pulse signal (sensor signal) by the comparator and sent to ECM.

Receiving this pulse signal (4 pulses/revolution), ECM detects the engine speed and the piston position of each cylinder and uses that information as one of signals to control the fuel injector and ignition timing.