Diaphragm Unit

The diaphragm box is controlled through a hose from the turbocharger via a solenoid valve. A coil spring in the diaphragm box normally keeps the wastegate valve closed. The ECM supplies a PWM signal to the solenoid valve to regulate the charge air pressure. The charge air pressure via the hose from the turbocharger overcomes the force of the coil spring in the diaphragm box and the wastegate valve starts to open.