CMP Actuator System Operation

WARNING: This page is about a different car, the 2006 Pontiac Montana SV6, 2006 Chevrolet Uplander, and 2006 Buick Terraza. However, it is still accessible from the selected car via links, so may be relevant.

The camshaft position (CMP) actuator system is controlled by the control module. The control module sends a pulse width modulated 12-volt signal to a CMP actuator solenoid in order to control the amount of engine oil flow to a Cam Phaser passage. There are 2 different passages for oil to flow through, a passage for cam advance and a passage for cam retard. The Cam Phaser is attached to a camshaft and is hydraulically operated in order to change the angle of the camshaft relative to crankshaft position (CKP). Engine oil pressure (EOP), viscosity, temperature and engine oil level can have an adverse affect on Cam Phaser performance. The control module calculates the optimum cam position through the following inputs:

Engine speed
Manifold absolute pressure (MAP)
Throttle position indicated angle
CKP
CMP
Engine load
Barometric (BARO) pressure

The Cam Phaser default position is 0 degrees. The control module uses the following inputs before assuming control of the Cam Phaser:

Engine coolant temperature (ECT)
Closed loop fuel control
Engine oil temperature (EOT)
EOP
Engine oil level
CMP actuator solenoid circuit state
Ignition 1 signal voltage
BARO pressure