Idle Speed Control (ISC) Valve

ISC valve, mounted on throttle body, controls idle smoothness by regulating throttle plate by-pass air. ISC valve consists of an air by-pass valve and idle speed control solenoid valve. Air by-pass valve functions during cold engine conditions, at temperatures less than 122°F (50°C). ISC solenoid valve works throughout entire temperature range. Air by-pass valve is affected by engine coolant temperature. ISC solenoid is controlled by PCM.

Idle is controlled by ISC air by-pass valve. Throttle air by-pass valve is a solenoid-operated valve controlled by PCM. Valve allows air to by-pass throttle plates to control cold engine fast idle, no-touch start, dashpot, over temperature idle boost and engine load idle correction.

Air by-pass channel carries idle airflow regulated by air by-pass valve. Air by-pass valve is controlled by PCM to adjust both cold and warm idle speeds. Air by-pass valve uses solenoid valve to vary idle airflow volume allowed to enter engine.