Camshaft Position Actuator System Operation

The camshaft position actuator system is controlled by the engine control module (ECM). The ECM sends a pulse width modulated, 12 V signal to the camshaft position actuator solenoid to control the amount of pressurized engine oil, into the camshaft position actuator. A low reference circuit, or ground wire between the camshaft position actuator solenoid and the ECM completes the electrical circuit. The frequency of the pulse width modulated signal is fixed at 150 Hz. To regulate the pressurized engine oil into the camshaft position actuator, the solenoid uses electromagnetic force on the solenoid pintle to pulse the oil control spool valve. The pressurized engine oil is sent to unseat the locking pin, and to the vane and rotor assembly of the camshaft position actuator, to either retard or advance the valve timing. The ECM will control the amount of ON time applied to the solenoid, through the 12 V signal from the ECM.

The ECM uses the following inputs to calculate the optimum valve timing before assuming control of the camshaft position actuator:

• Engine speed
• Manifold absolute pressure
• Throttle position angle
• Camshaft position sensor
• Crankshaft position sensor
• Crankshaft/camshaft correlation
• Engine coolant temperature
• Closed loop fuel control
• Engine oil pressure
• Engine oil level
• Camshaft position actuator solenoid circuit state