Idle Speed/Throttle Actuator - Electronic: Description and Operation

Idle Air Valve:

The idle air valve provides control for constant idle speed. In order to set the correct air valve opening to achieve constant idle speed, the fuel injection control unit uses information from the air mass/flow meter, throttle valve switch and the ignition control unit (RPM signal) to regulate the output current to the idle air valve.

OPERATION
When the throttle valve switch idle contacts are closed during idling, the fuel injection control unit will send a current to the idle air valve electric motor to keep the idle speed at the correct level. This speed is preset in the fuel injection ECU and should remain constant disregarding engine load or conditions.
If the throttle valve switch idle contacts are open (engine above idle speed), the fuel injection ECU will not send a current. The idle air valve will close to its default position, thus staying partially open so the vacuum in the intake manifold is reduced when the throttle valve suddenly closes.