Theory Of Operation
WARNING: This page is about a different car, the 2014 Dodge Journey. However, it is still accessible from the selected car via links, so may be relevant.
When the ignition switch is in the RUN position, and the Telematics Gateway (TGW) is in the video mode. The TGW sends an audio signal to the Video Screen Module, using circuits (X545) Channel 2 Audio Left and (X546) Channel 2 Audio Return.