Idle Speed/Throttle Actuator - Electronic: Description and Operation

IDLE AIR CONTROL (IAC) VALVE




The idle air control (IAC) valve is attached to the underside of the throttle body with 4 bolts. The IAC valve enables the powertrain control module (PCM) to easily control the engine idle speed by precisely metering the engines air intake at closed throttle. The IAC valve opens and closes the idle air bypass passage according to signals from the PCM. The IAC valve contains an engine coolant passage that enables the IAC valve to operate more efficiently at cold temperatures. The PCM determines the correct engine idle speed by using input from various sensors and switches in order to assess the engine status and requirements.