Idle Speed/Throttle Actuator - Electronic: Description and Operation

Description

The Idle Speed Control Actuator (ISCA) is installed on the throttle body and controls the intake airflow that bypasses the throttle plate to keep constant engine speed when the throttle valve is closed.
The function of the ISCA is to maintain idle speed according to various engine loads and conditions, and also to provide additional air during starting.
The ISCA consists of an opening coil, a closing coil, and a permanent magnet. Based on information from various sensors, the ECM controls both coils by grounding their control circuits. According to the control signals from the ECM, the valve rotor rotates to control the by-pass airflow into the engine.