Camshaft Position Sensor: Description and Operation
CAMSHAFT POSITION SENSORDESCRIPTION
The camshaft position (CMP) (1) sensor is mounted in the top of cylinder head cover/intake manifold at the rear of the engine.
The CMP sensor (1) is a hall effect device that detects a notch on the rear of the exhaust camshaft that allows the ECM to determine the position of cylinder number one. The engine will continue to run if the signal is lost, but will not restart after the vehicle is shut off.
OPERATION
The camshaft position (CMP) sensor is a hall effect switch. A tooth made of a ferromagnetic material is attached to the camshaft. When this tooth passes the CMP sensor an electronic signal is created. This signal is then sent to the engine control module (ECM). This signal is used by the ECM to determine TDC and which cylinder has just entered its compression phase.
The camshaft position sensor (2) is mounted on the cylinder head cover toward the rear of the engine. The camshaft sensor utilizes a non contact method on one segment of the camshaft to record the camshaft position. When the ECM receives the signal from this sensor, it can then detect TDC of cylinder number one.The signal from the camshaft sensor is only required during engine starting. Injection timing is synchronized by means of the camshaft signal and the crankshaft signal.
On the camshaft sensors signal line, a high signal corresponds to a voltage of 0-5V. If the segment machined into the exhaust camshaft sprocket is positioned opposite the camshaft sensor, the camshaft signal is low, approximately 0 V. This signal is used by the engine control module (ECM) for detecting ignition TDC of cylinder 1 as the engine rotates. If no signal is supplied by the camshaft position sensor, the vehicle will not start because cylinder order cannot be detected. If the signal is lost while the engine is running the vehicle will continue to run until shut off.