Wastegate Solenoid: Description and Operation

PURPOSE/OPERATION
The wastegate solenoid valve is an electromechanical, vacuum switching valve the allows the engine control module to reduce boost pressure. This is to maintain optimum boost pressure under all driving conditions and prevent engine damage during component failures or detonation. The wastegate solenoid is spring loaded in the closed (lowest boost) position until after the engine is started. The solenoid is powered by the control relay. The engine control module completes the circuit to ground (highest boost) while the engine is running. When the solenoid is energized, boost pressure to the wastegate actuator is bled back to the air filter housing and the wastegate stays closed. When the engine control module detects detonation or sensor failure, the ground circuit is interrupted, solenoid turns off and full manifold pressure is applied to the wastegate.

The engine control module uses the following vehicle load condition inputs to regulate the on off signal to the solenoid:
- Detonation sensor
- Air flow sensor
- Engine RPM
- Barometric pressure sensor
- Intake air temperature sensor


The engine control module does not control boost pressure it only regulates it during failures of the control components.