Do you have a motorhome or a trailer? I understand that trailers have some brake wiring in the negative battery lead, breakaway brake. My experience is with my Class C MH. I am also talking about the house 12v system, not the chassis 12v system.
My house 12v system uses the chassis as the negative 12v. The battery -12v is connected directly to ground with one #2 AWG wire. This is where I put my ammeter.
There is no wire running from the -12v battery post to the 12v power distribution panel. The 12v power distribution panel is connected to chassis ground. AFAIK, this is how most Class Cs are wired.
That is the way my house 12v system is wired. If yours is different, I guess I'm not much help. Yes I do have a Genny, a Generac, not an Onan.
