Circuit/System Description

The camshaft position actuator system enables the engine control module (ECM) to change camshaft timing while the engine is running. The camshaft position actuator assembly varies relative camshaft position (phasing) in response to changes in oil pressure control passages to the actuator. The camshaft position actuator solenoid valve controls the oil pressure supplied to the control passages to advance or retard the camshaft. Modifying camshaft timing under changing engine demand provides better balance between the following performance concerns:

• Engine power output
• Fuel economy
• Lower exhaust emissions

The ECM uses information from the following sensors in order to calculate the desired camshaft position:

• The engine coolant temperature (ECT) sensor
• The mass air flow (MAF) sensor
• The throttle position sensor
• The vehicle speed sensor (VSS)