Sonata V6-3.0L (1991)
Idle Speed/Throttle Actuator - Electronic: Description and Operation
Idle Speed Control (ISC) System
The Idle Speed Control (ISC) Systems Primary function is to regulate the control of the idle to adjust 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 system adjusts the idle for air conditioning
and automatic transmittion loads and is used as a fast idle for cold start. The ECU uses the idle speed control (ISC) servo, also called a stepper motor, to
make all of the adjustments to the idle.
Idle Speed Control Servo (Stepper Motor)
The ISC servo consists of a stepper motor linked to the throttle shaft linkage. An idle switch is used to detect idle position. As the motor rotates,
according to the signal from the ECU, the throttle valve is actuated via the throttle shaft linkage. In this way, the idle speed is controlled by changing the
throttle valve opening.