Camshaft Position Actuator Solenoid Valve

WARNING: This page is about a different car, the 2003 Pontiac Vibe. However, it is still accessible from the selected car via links, so may be relevant.

The CMP actuator solenoid valve directs the oil flow that controls the camshaft phase movement. The PCM commands the CMP solenoid to move the solenoid plunger and spool valve until oil flows from the advance passage or the retard passage. In most operating conditions the opposite oil return passage is open at the same time as the oil supply passage. See Fig 1 .

Fig 1: Identifying Camshaft Position Actuator Solenoid Valve Components

Courtesy of GENERAL MOTORS CORP.

The PCM operates the CMP actuator solenoid valve by Pulse Width Modulation (PWM) of the solenoid coil. The higher the PWM duty cycle, the larger the change in camshaft timing. Oil pressure that is applied to the advance side of the fixed vanes will rotate the camshaft in a clockwise direction. The clockwise movement of the camshaft will advance the timing up to a maximum of 21 degrees. When oil pressure is applied to the return side of the vanes, the camshaft will rotate counterclockwise until returning to zero degrees.