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.