Idle Speed/Throttle Actuator - Electronic: Description and Operation

Isle Speed Control (ISC):

PURPOSE
The idle speed control valve (ISC) maintains proper idle speed under various engine demand periods. The ECU directly controls operation of the ISC valve.

LOCATION
Mounted to the front of the air intake chamber.

CONSTRUCTION
The unit consists of a 4-winding stepper motor and a variable air passage.

OPERATION
By alternating signals to the individual coils the ECU is able to pull the valve open and closed. The shaft of the stepper motor allows for 125 individual positions of the valve.

As the valve opens and closes air is allowed to bypass the throttle body, changing base idle speed.