Idle Speed/Throttle Actuator - Electronic: Description and Operation

Idle Speed Control (ISC) Solenoid:

PURPOSE
The Idle Air Control (IAC) valve controls idle speed during all modes of engine operation.

OPERATION
The IAC valve receives duty cycle signals from from the Powertrain Control Module (PCM), controlling a rotary valve opening or closing the air by-pass passage depending on the signal received. The valve will rotate to a half opened position as the signal from the PCM stops. This assures bypass air to the engine is maintained as a fail-safe measure in the event of an electrical circuit malfunction.