Idle Speed/Throttle Actuator - Electronic: Description and Operation

The idle speed control/bypass air valve controls idle speed by regulating air that bypasses the throttle plate.

There are two parts to the (ISC-BPA). The bypass air valve (BPA) and the idle speed control solenoid (ISC). The BPA valve is thermally controlled and functions only during cold engine conditions (below 140 degrees F). The ISC valve is controlled by the electronic control assembly and operates under all engine speed and temperature conditions.