Theory Of Operation
WARNING: This page is about a different car, the 2017 Jeep Cherokee. However, it is still accessible from the selected car via links, so may be relevant.
The RADIO controls and monitors both the microphone 2 input circuit (+) and the microphone 2 input circuit (-) for a concern. The RADIO communicates over the CAN-Interior Bus. The microphone is located in the rearview mirror.