Circuit/System Description

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The camshaft position (CMP) actuator system enables the engine control module (ECM) to change the timing of the camshaft while the engine is operating. The ECM controls the camshaft position actuator magnet duty cycle by controlling the amount of ON time. The magnet controls the amount of engine oil flow to the CMP actuator by extending a pintle within the solenoid. The pintle acts against a spool valve in the CMP actuator mechanism which is attached to the front of the camshaft. As the spool valve is moved, oil is directed to the CMP actuator, which rotates the camshaft. The ECM can only command the camshaft position 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 26 degree as measured at the camshaft or 52 degree as measured at the crankshaft.

The ECM controls the camshaft position actuator magnet by suppling a 12 V pulse width modulated (PWM) signal. The ECM supplies a ground to the low reference circuit.