Circuit Description

The P0012 Intake Camshaft Position (CMP) System Performance - Retarded diagnostic monitors the operation of the CMP actuator solenoid. The CMP actuator solenoid enables the powertrain control module (PCM) to change the intake camshaft timing while the engine is running. The CMP actuator solenoid contains a spool valve that controls the advance of the camshaft. The CMP actuator solenoid is controlled by a pulse width modulated (PWM) signal from the PCM. The CMP sensor monitors the camshaft position or the camshaft angle, and compares that position or phase to the crankshaft position (CKP) sensor signal. The PCM determines whether the camshaft angle is correct by comparing the actual camshaft position to the target camshaft position. By continuously analyzing the input of the CMP sensor and the CKP sensor the PCM can detect a fault in the CMP actuator system. For additional information on the operation of the CMP actuator system refer to Camshaft Actuator System Description .