Circuit Description

The camshaft position (CMP) sensor provides the powertrain control module (PCM) with a signal representing the camshaft's rotational position. The CMP sensor is a hall effect switch that works in conjunction with a 4X reluctor wheel. The reluctor wheel consists of 4 pairs of rising and falling edges that are differently spaced. The CMP sensor produces a magnetic field. When the camshaft rotates, and the reluctor wheel edge passes by the CMP sensor, there is a change in the magnetic field. The PCM views each transition from low to high as one signal. The PCM receives 4 signals per camshaft revolution. The CMP sensor has the following circuits:

• A 5-volt circuit
• A low reference circuit
• A signal circuit

The PCM supplies 5 volts to the CMP sensor on the 5-volt reference circuit, and provides a low reference circuit. The CMP sensor provides a 4X signal to the PCM on the signal circuit. If the PCM detects extra or missing CMP sensor signal transitions within a certain number of crankshaft revolutions, DTC P0340 will set.