The Idle Charge Actuator (ISCA) vlave is installed on the intake manifold and controls the intake airflow that is bypassed around the throttle plate to keep constant engine speed when the throttle vlave is closed. The function of the ISCA valve is to maintain idle speed according to various engine loads and conditons, and also to provide additional air during starting. The ISCA vlave consists of an opening coil, a closing coil, and a permanent magnet. Based on information from various sensor, the ECM controls both coils by grounding their control circuits. According to the control signals from the ECM, the valve rotor rotates to control the by pass airflow into the engine.

ECM sets DTC P1508 if the ECM detects that the ISCA(CLOSE) control circuit is short to battery.