Idle Speed Control (ISC) System

ISC system provides start control, fast idle control, idle control and dashpot control. Start control adjusts throttle valve opening according to coolant temperature and atmospheric pressure.

Fast idle control is determined by idle switch position. When idle switch is on, engine speed is controlled according to coolant temperature. When idle switch is off, ISC servo is actuated according to engine coolant temperature.

Idle control increases idle speed when power steering oil pressure switch or A/C switch is turned on or when transmission is shifted from Neutral to Drive (automatic transmission only). Dashpot control delays closing of throttle valve to its normal idling position.