The solenoid valve switches the intake manifold vacuum passage between the intake manifold and the actuator. When the power is turned on, the valve plug is pulled and opens a passage between the air channels A and B, which provides access to the atmospheric air valve actuator. When the power is turned off, the plunger back and forth between the air passage open channels B and C, which gives access to vacuum from the intake manifold to the actuator valve. Solenoid valve comprises a solenoid, a spring plunger and a filter
(Fig. 2.59).