•  Power to the exhaust shutter solenoid valve is supplied when the exhaust shutter solenoid valve relay is energized by the on signal from the PCM, then the airflow circuit is switched.

•  When the exhaust shutter solenoid valve is energized, the circuit from the vacuum pump to the exhaust shutter valve actuator is established.

•  When the exhaust shutter solenoid valve is not energized, the circuits on the exhaust shutter valve actuator side and the release side are established.