Circuit/System Description

WARNING: This page is about a different car, the 2008 GMC Sierra, 2008 GMC Cab & Chassis Sierra, 2008 Chevrolet Silverado, and 2008 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The camshaft position (CMP) actuator solenoid is controlled by the engine control module (ECM). The ECM sends a 12 volt, pulse width modulated (PWM) signal to the CMP actuator solenoid. The CMP actuator solenoid positions the CMP actuator spool valve to control the amount of pressurized engine oil, which enters into the CMP actuator assembly. A low reference wire circuit between the CMP actuator solenoid and the ECM completes the electrical circuit. The frequency of the pulse width modulated signal is fixed at 150 Hz. The ECM can only command the CMP actuator to retard the valve timing from the camshaft park position, or advance the valve timing back to the park position. The total range of valve timing command is 31 degrees as measured at the camshaft, or 62 degrees as measured at the crankshaft.