Idle Speed Control (ISC)

The ISC is an electrically-driven actuator which opens or closes throttle (in idle position) according to commands from ECM. The ISC maintains low idle speeds, while preventing stalls due to engine load changes.

The ECM receives signals from A/C "ON" switch, Park-Neutral switch and ISC throttle switch. This information is used to determine idle speed required to prevent engine stalling. ECM controls idle speed switch by operating the ISC motor.

When engine is cold, ECM holds throttle valve open for longer period of time to provide faster warm-up. This function is by-passed when throttle is opened enough to bring TPS off its idle circuit. The ISC is located on side of carburetor.