Camshaft Position Sensor: Description and Operation

CAMSHAFT POSITION (CMP) SENSOR

This system consists of 2 different camshaft position (CMP) sensors, the exhaust CMP sensor and the intake CMP sensor. The exhaust CMP sensor is triggered by a notched reluctor wheel built into the exhaust CMP actuator. The CMP sensor provides 5 signal pulses every camshaft revolution. Each notch, or feature of the reluctor wheel, is of a different size for individual cylinder identification. This means the CMP and crankshaft position (CKP) signals are pulse width encoded to enable the powertrain control module (PCM) to constantly monitor their relationship. This relationship is used to determine camshaft actuator position and control its phasing at the correct value. The PCM also uses this signal to identify the compression stroke of each cylinder, and for sequential fuel injection. The intake CMP sensor is triggered by a 1X reluctor wheel built into the intake camshaft sprocket. The CMP sensor provides one signal pulse every camshaft revolution. The PCM monitors this signal and the CKP signal for startability. Both of the CMP sensors are connected to the PCM by a 12-volt circuit, a low reference circuit, and a signal circuit. The 12-volt reference circuit is shared by the 2 sensors, while the low reference circuit and the signal circuit is independent.