Idle Speed/Throttle Actuator - Electronic: Description and Operation

Throttle Body Electrical Connections:

The engine controller operates the Automatic Idle Speed (AIS) motor to maintain the proper idle speed for all operating conditions. Inputs from the throttle position sensor, speed sensor, and coolant temperature sensor are used by the engine controller to calculate the proper idle speed. Various switches (brake, neutral/safety) are also used to provide input for the idle speed.

The AIS varies the air portion of the air/fuel mixture in the air bypass passage of the throttle body. It does this by extending or retracting the AIS pintle into the air bypass passage. The further the AIS pintle protrudes into this passage the slower the idle speed, and the less the AIS pintle protrudes the greater the idle speed. The engine controller adjusts the pintle position to compensate for various engine loads and operating conditions. Deceleration stall is also prevented by increasing the airflow when the throttle is closed suddenly. The AIS motor is mounted below the throttle position sensor (TPS) on the throttle body.