Barometric Pressure Sensor: Description and Operation

OPERATION
On diesel engines, the BAROMETRIC PRESSURE SENSOR (BARO) senses atmospheric pressure to produce an electrical signal. The frequency of this signal varies with altitude the sensor operates similar to the manifold absolute pressure sensor, It measures barometric pressure instead of intake manifold pressure. The powertrain control module uses the signal from the barometric pressure sensor to determine the altitude at which the vehicle is operating. The powertrain control module then adjusts the E4OD shift schedule for the altitude.

PURPOSE
The BARO sensor is used as an input to determine shift schedule and electronic pressure control for altitude operation.

SYMPTOMS
Firm shift feel, late shifts at altitude.

DIAGNOSTIC TROUBLE CODES:
- 22, 72 (two digit)
- 126, 128, 129 (three digit).