Idle Speed/Throttle Actuator - Electronic: Description and Operation

Throttle Position Sensor (TPS)/Automatic Idle Speed (AIS) Motor:

LOCATION

Idle Air Control (IAC) motor is mounted on throttle body.

FUNCTION

Motor maintains optimum idle speed under varying engine loads, and prevents deceleration die out.

OPERATION

The Automatic Idle Speed (AIS) motor controls air flow through a passage connected to both intake manifold plenums. The engine controller maintains engine idle speed, by adjusting the IAC motor to compensate for engine load or ambient conditions.

The AIS varies the amount of air that is allowed to bypass the throttle blades. It does this by extending or retracting the AIS pintle into the idle air passage. The further the AIS pintle protrudes into this passage the slower the idle speed, and the less the IAC pintle protrudes the greater the idle speed.

Deceleration stall is also prevented by increasing the airflow when the throttle is closed suddenly

The engine controller calculates proper idle speed using information from throttle position, vehicle speed, and coolant temperature sensors and brake, and neutral/safety switches.