BARO / MAP Sensor Switching Valve: Description and Operation

SYSTEM DESCRIPTION
This system allows the absolute pressure sensor to monitor either ambient barometric pressure or intake manifold pressure. The MAP/BARO switch solenoid valve switches between two passages by ON-OFF pulse signals from the ECM. (One passage is from the intake air duct, the other is from the intake manifold.) Either ambient barometric pressure or intake manifold pressure is applied to the absolute pressure sensor.

Solenoid / Conditions
ON
- Ignition switch is "ON". (Engine is not running.)
- For 5 seconds after starting engine
or
- More than 5 minutes after the solenoid valve shuts OFF.
and
- Throttle valve is shut or almost fully shut for more than 5 seconds
and
- Vehicle speed is less than 100 km/h (62 MPH).

COMPONENT DESCRIPTION




The MAP/BARO switch solenoid valve switches its air flow passage according to the voltage signal sent from the ECM. When voltage is supplied from the ECM, the MAP/BARO switch solenoid turns "ON". Then, the absolute pressure sensor can monitor the ambient barometric pressure. When voltage is not supplied from the ECM, the MAP/BARO switch solenoid valve turns "OFF". Then, the sensor monitors intake manifold pressure.