Barometric Pressure Sensor: Description and Operation

Barometric Pressure (BARO) Sensor Operation:

PURPOSE
The ECM uses the BARO sensor signal to sense changes in altitude so that ignition timing and fuel delivery can be adjusted to maintain consistent engine performance.

CONSTRUCTION
The sensor consists of a silicon diaphragm and some support circuitry. The diaphragm covers a sealed cavity.

OPERATION
The ECM supplies a 5 volt signal and a ground to the sensor. Changes in the pressure differential between the sealed cavity and the atmosphere cause the silicon to flex. The flexing of the silicon generates a small voltage which is amplified by the support circuitry and used to modify the fixed 5 volt signal supplied by the ECM. The modified signal is then returned to ECM.