Idle Speed/Throttle Actuator - Electronic: Description and Operation

The Idle Speed Control (ISC) servo regulates and controls the idle for the loads placed on the engine. The ECU uses several sensor inputs to determine the operating condition of the engine and the loads being placed on it. The ECU adjusts the idle for air conditioning and automatic transmission loads and controls fast idle for cold start. The ECU uses the idle speed control (ISC) servo to make all of the adjustments to the idle.

ISC Stepper Motor Location:

ISC Sectional View:

The ISC servo is a stepper motor that regulates the amount of air taken in through the bypass circuit of the intake manifold by opening and closing the servo valve located in the air passage. The ISC servo is located on the throttle body.