CMP Actuator System Operation

The camshaft position CMP actuator system is controlled by the powertrain control module (PCM). The PCM 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. Engine oil pressure, viscosity, temperature and engine oil level can have an adverse affect on cam phaser performance. The PCM calculates the optimum cam position through the following inputs:

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

The cam phaser default position is 0 degrees. The PCM uses the following inputs before assuming control of the cam phaser:

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