Outside Air Temperature Display

The ambient air temperature sensor is hardwired to the PCM through separate input and return circuits. The PCM provides a reference voltage to the ambient air temperature sensor and monitors the change in voltage resulting from changes in resistance as determined by outside air temperature. The PCM filters the ambient air temperature input and sends the BCM the air ambient temperature filtered message. The BCM sends the air ambient temperature filtered message to the IPC.

The PCM is programmed to update the messaged outside temperature data at different rates depending on several criteria to prevent false temperature displays due to a condition known as heat soaking. Heat soaking is where the outside air temperature is hotter in the location of the ambient air temperature sensor than the actual outside air temperature.

When the sensed outside temperature rises, the display updates slowly at varying rates based on vehicle speed. When the sensed outside temperature drops, the display updates more quickly basically following the drop experienced by the ambient air temperature sensor.