Idle Speed Control (ISC)

Engine idle speed is controlled by the ECU depending upon engine operating conditions. The ECU senses engine operating conditions and determines the best idle speed. Under any (depending upon system) of the following conditions the ECU will send an on signal to compensate idle speed: starting to 20 seconds after start, low battery voltage, headlights on, heater switch on, rear defogger on, power steering oil pressure switch on, radiator fan switch on, during deceleration and vehicle moving at idle. The ECU then sends an electronic signal to either the idle-up solenoid or the Auxiliary Air Control (AAC) valve (depending upon system) to either reduce or increase idle speed.