Accessory Signal: Description and Operation

Throttle Opening System:

Based on the Tail Light Switch and other load indicating signals, the ECU controls the grounds for 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 tail light 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.