Outside Air Temperature

WARNING: This page is about a different car, the 2018 Ford EcoSport. However, it is still accessible from the selected car via links, so may be relevant.

The Ambient Air Temperature (AAT) sensor is hardwired to the PCM through separate input and return circuits. The PCM provides a reference voltage to the Ambient Air Temperature (AAT) sensor and monitors the change in voltage resulting from changes in resistance as determined by outside air temperature.

The PCM provides the ambient air temperature data to the GWM over the HS-CAN1. The GWM sends the ambient air temperature data message to the HVAC module over the MS-CAN. The HVAC module sends the filtered ambient air temperature data to the IPC over the HS-CAN3.

The HVAC module is programmed to update the messaged outside temperature data at different rates depending on several criteria (current engine temperature, engine off time and vehicle speed) 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 (AAT) sensor than the actual outside air temperature.