Barometric Pressure Switch: Description and Operation

SYSTEM DESCRIPTION
This system provides the absolute pressure sensor with either ambient barometric pressure or intake manifold pressure for monitoring.
The MAP/BARO switch solenoid valve switches between two passages (one is from the air duct, the other is from the intake manifold) by ON-OFF operation. When the MAP/BARO switch solenoid valve is activated ON or OFF by the ECM, either ambient barometric pressure or intake manifold pressure is applied to the absolute pressure sensor.
The solenoid valve is almost always OFF under normal conditions.






COMPONENT DESCRIPTION
The MAP/BARO switch solenoid valve switches between ambient barometric pressure and intake manifold pressure according to the voltage signal sent from the ECM. When the MAP/BARO switch solenoid valve is supplied with a voltage by the ECM, it turns "ON" so that the MAP/BARO switch solenoid valve monitors the ambient barometric pressure. When the MAP/BARO switch solenoid valve is not supplied the voltage, it goes "OFF" and the sensor monitors the intake manifold pressure.