LR3 (LA) V8-4394cc 4.4L (2005)
Barometric Pressure Sensor: Description and Operation
Barometric Pressure Sensor
The Barometric pressure sensor (also referred to as the High Altitude Compensation sensor) is located within the ECM.
High /Low Input Failure
These are continuous monitors. The voltage from the sensor is compared to a failure threshold defined in the software. If the voltage is below the low
threshold, then a timer starts to increment. Once this timer exceeds another threshold, then a failure flag is set and a DTC is stored. If the voltage is over
the high threshold defined in the software, then a timer starts to increment. Once this timer exceeds a threshold, then a failure flag is set and a DTC is
Range / Performance Failure
The signal from the sensor is compared to the signal from the Manifold Absolute Pressure sensor (MAP) at ignition on only. During this time the
pressure within the inlet manifold should be at atmospheric, and therefore should match the value from the barometric pressure sensor.
The following conditions must be met first before the monitor can execute;
Engine speed = 0
Vehicle speed = 0
Monitor is not inhibited
Ignition is on
Engine is not cranking
Battery voltage exceeds minimum threshold
Coolant temp above minimum threshold
Atmospheric pressure within limits
Inlet manifold pressure value has settled
If the absolute value of the difference between the signal from the barometric pressure sensor and the MAP sensor differ by more than a defined amount,
then a timer is executed. If the timer exceeds a calibrated amount, a temperature failure is judged. Providing there is no failure of the MAP sensor, a
DTC is then stored.