Exhaust Valve Opening Strategy (Normal and Sport Transmission Modes)

The ECM energizes the active exhaust relay in the AJB (auxiliary junction box) 5 seconds after the ignition is switched on. When the relay is energized, it supplies power to the vacuum pump and the solenoid valve. The vacuum pump is connected to ground and runs continuously while the relay is energized, maintaining a depression in the reservoir and pipes to the solenoid valve.

The solenoid valve is connected to ground through the ECM. When the ECM determines the exhaust valves require closing, it connects the solenoid valve to ground. When the solenoid valve energizes, it opens the pipe connection from the reservoir and vacuum pump to the exhaust valves, and closes the atmospheric vent. The depression at the reservoir and vacuum pump is then sensed at the exhaust valves, via the check valve, and the exhaust valves close. When the ECM determines the exhaust valves require opening, it disconnects the solenoid valve from ground. The solenoid valve de-energizes and closes the pipe connection to the exhaust valves, and opens the atmospheric vent. Atmospheric pressure is then sensed at the exhaust valves, via the restrictor, and the exhaust valves open.