Blower Motor Switch: Description and Operation

Throttle Opening System:

Based on the Blower Fan Switch and other load indicating signals, the ECU controls the ground to the throttle opener system. When the ECU provides a ground it allows operation of the throttle openers for either or both of the idle speed devices. In the case of the Blower Fan Switch, the idle up relay is provided a ground, and the idle up solenoid valve is energized to introduce intake manifold vacuum to the idle up throttle opener. The idle up throttle valve opens slightly preventing engine speed drop caused by electrical load.