AVC-LAN Circuit: Description
WARNING: This page is about a different car, the 2006 Toyota Camry Solara. However, it is still accessible from the selected car via links, so may be relevant.
Each unit of the radio and navigation system communicates by transferring signals for each of its own switches through the AVC-LAN (communication bus).
If a +B or GND short occurs in the AVC-LAN, the radio and navigation system cannot function normally, as communication ceases.