Idle Speed/Throttle Actuator - Electronic: Description and Operation

Idle Speed Control (ISC) Solenoid:

The Idle Speed Control (ISC) solenoid controls idle speed during all modes of engine operation. The ISC solenoid receives duty cycle signals from from the Electronic Control Assembly (ECA), controlling a rotary valve that opens or closes the air by-pass passage depending on the signal received. The valve will rotate to a half opened position as the signal from the ECA stops. This assures by-pass air to the engine is maintained as a fail-safe measure in the event of an electrical circuit malfunction.