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, which functions during cold engine conditions below 122°F (50°C), and the idle speed control solenoid valve, which works throughout the entire temperature range. The air by-pass valve is affected by the engine coolant temperature. The idle speed control solenoid is controlled by ECA.

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. The valve allows air to by-pass throttle plates to control cold engine fast idle, no-touch start, dashpot, overtemperature 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.