There should be a supplied usb with diagrams inside one of the electrical cabinets mounted to the din rails
One Azimut dealer told me, they don't even bother tracing wires on them. They just run new wires point to point.
Interesting, second horn question on a Mut in 15 minutes. Please see https://www.yachtforums.com/threads/new-azimut-50-fly.27110/page-3 #51, 52