Idle Speed/Throttle Actuator - Electronic: Description and Operation

Bypass Air Control Valve:

PURPOSE
The bypass air control valve modifies idle speed to bring it as close as possible to preset limits.

OPERATION
Whenever the engine is running the control valve receives a duty cycle type signal from the ECM. Engine speed is modified by the duty control valve. By altering the amount of air allowed to bypass the throttle plate, idle speed is adjusted as needed.