Engine Idle Speed Control (ISC)

The ECM controls idle speed based on engine load and temperature. Engine idle speed is kept at the optimum speed by controlling amount of air that by-passes throttle valve. ECM commands ISC actuator to keep the engine running at a pre-set idle target speed in accordance with the engine temperature and power steering (if equipped) and air conditioning loads. When engine load increases because of power steering and/or air conditioning activation, the ECM will increase engine idle speed to avoid fluctuations in engine speed.