Camshaft Reset Valve (Continuous Variable Valve Timing (CVVT))

Fig 1: Identifying Camshaft Reset Valve (Continuous Variable Valve Timing (CVVT))

Courtesy of VOLVO CARS OF NORTH AMERICA.

The camshaft reset valve controls the oil flow to the CVVT unit (camshaft pulley).

The valve consists of an electro-magnetic valve with a spring-loaded piston. There are slits in the piston which channel the engine lubricating oil to the CVVT unit by moving the piston in the reset valve. The continuous variable valve timing (CVVT) unit turns the camshaft (the camshaft timing changes). The direction in which the camshaft turns depends on the chamber in the CVVT unit which is supplied with oil (pressure). See: CAMSHAFT CONTROL (CVVT) 

The system relay supplies the reset valve with voltage. The valve is grounded (control stage) in the engine control module (ECM). When the valve is grounded using a pulse width modulation (PWM) signal, the oil flow in the valve can be regulated to the different chambers in the continuous variable valve timing (CVVT) unit at variable rates. This allow the angle of the camshaft to be changed precisely and smoothly.

The engine control module (ECM) can diagnose the camshaft reset valve.

The valve is on the cylinder head above the camshaft with camshaft control.