Variable Camshaft Timing (VCT) Solenoids

Two VCT actuator valve solenoid valves are used; one for the inlet camshaft and one for the exhaust camshaft. The solenoid valves are located in the top of the camshaft cover and are secured with a bolt and sealed with O ring seals assemblies.

The solenoid valves are located in holes in the front camshaft bearing cap. The bearing cap contains drillings which direct pressurized engine oil to the valve control ports. The pressurized engine oil is supplied through a central bore in the bearing cap. The bore contains a filter to remove any debris from the oil to avoid contamination of the solenoid valves spools. The oil passes through the filter and is directed via drilling to each solenoid valve spool.

The valve spool is moved by the solenoid which is actuated by PWM (pulse width modulation) signals from the ECM.

Each VCT actuator solenoid valve contains a coil and an armature. The ECM actuates the solenoid with a PWM of up to 300 Hz. The solenoid valve is controlled linearly over its operating range from 0 to 1000 mA. Approximately 560 mA is required to hold the valve in the neutral position so the oil supply to the retard and advance adjustment control ports are closed.

If the ECM detects a fault with one or both VCT actuator solenoid valves, the ECM will not operate them and therefore VCT operate will be disabled and the camshaft will operate in their default position.