Idle Speed/Throttle Actuator - Electronic: Description and Operation

PURPOSE AND OPERATION
The idle air control valve (IACV) is designed to automatically maintain engine idle speed when the engine is under increased loads (electrical and/or mechanical).

The electronic control unit (ECU) controls engine idle speed by adjusting the IACV to compensate for increased engine loads. The ECU sends voltage signals to a pair of motor control windings inside the IACV. This allows the ECU to reverse the voltage signals to the control valve, moving the IACV in or out to vary air flow to the plenum chamber. Opening allows extra air into the plenum chamber causing the idle to increase idle speed. Closing reduces that amount of extra air, reducing idle speed.