Ambient Air Temperature Sensor
WARNING: This page is about a different car, the 2018 Land Rover Discovery and 2017 Land Rover Discovery. However, it is still accessible from the selected car via links, so may be relevant.
The Ambient Air Temperature (AAT) sensor is a Negative Temperature Coefficient (NTC) thermistor installed in the left exterior rear view mirror. The bulb of the sensor is positioned over a hole in the bottom of the mirror casing.
The Powertrain Control Module (PCM) supplies the AAT sensor with a 5V reference voltage and translates the return signal voltage into a temperature. The PCM transmits the temperature on the FlexRay circuit for use by other systems. The Automatic Temperature Control Module (ATCM) receives the temperature on the High Speed (HS) Controller Area Network (CAN) Power Mode Zero bus via the Body Control Module/Gateway Module (BCM/GWM).
NOTE:
If the Ambient Air Temperature sensor is disconnected, for example the exterior mirror is removed, the sensor will need to be reset to the ambient temperature. The detail will be in the diagnostic and testing documentation.