Barometric Pressure Sensor: Description and Operation

Vacuum/Atmospheric Pressure Sensor and VLC Solenoid:

PURPOSE
Detects changes in intake manifold vacuum and atmospheric pressure and supplies the information to the EFC System control unit in the form of electrical signals.

LOCATION
Attatched to a bracket on the R.F. fender apron.

OPERATION
A vacuum line control (VLC) solenoid in line between intake manifold and sensor is switched by a voltage signal from the control unit. With no voltage to the solenoid, the sensor monitors intake manifold vacuum. When the solenoid is energized, the sensor measures atmospheric pressure. With this system, the control unit determines engine operating conditions (load, coasting, etc.) and can make air/fuel ratio adjustments consistent with changes in altitude.