Idle Speed Control (ISC) Valve

The ISC valve, mounted on the 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). Idle speed control solenoid valve works throughout entire temperature range. Air by-pass valve is affected by engine coolant temperature. Idle speed control solenoid is controlled by ECA/ECU.

Idle is controlled by idle speed control air by-pass valve. The throttle air by-pass valve is a solenoid-operated valve controlled by ECA/ECU. The 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 ECA to adjust both cold and warm idle speeds. Air by-pass valve uses solenoid valve to vary idle airflow volume allowed to enter engine.