Circuit Description

The camshaft position (CMP) sensor works in conjunction with the 4X reluctor trigger wheel on the camshaft gear. The reluctor trigger wheel on the camshaft gear contains a pattern around the circumference, consisting of 2 narrow teeth and 2 wide teeth. The engine control module (ECM) provides a 5-volt reference to the sensor, as well as a low reference and a signal circuit. As the camshaft gear rotates, the reluctor trigger wheel interrupts a magnetic field produced by a magnet internal to the sensor. The CMP sensor internal circuitry detects this interruption of the magnetic field, and produces an ON/OFF DC voltage of varying frequency. The frequency of the CMP sensor output signal is dependent upon camshaft speed. The ECM will recognize the narrow and wide tooth patterns to identify camshaft position, or which cylinder is in compression and which is in exhaust. If the ECM detects that there is no output signal from the CMP sensor, then DTC P0340 will set.