Idle Speed/Throttle Actuator - Electronic: Description and Operation

Idle Speed Control Valve (ISC):

The ECU receives input from various sensors and controls idle speed through the idle speed control valve. The ISC Valve provides an air bypass around the throttle valve with an electric motor that rotates a flap in the air passage. The ISC Valve has battery voltage applied to it and grounds back through the ECU via terminals ISC1 and ISC2. There is a bimetal thermal valve on the end of the ISC Valve that provides high idle at start-up.