Joe,
I only have my experience with a '60 Airstream and an '84 SOB to go on, but
both seem to be the same. There is a hot wire to the brake magnets and to
all the lights. Each item is grounded through the body and frame. (The
brakes ground through the magnet hitting the drum.) The battery is grounded
as well as the ground wire leading to the tow vehicle. Everything is
grounded that way. Ground with tow vehicle is through the hitch ball, the
weight bars and through the plug. Play it safe and wire the plug ground as
well. Some trailers use a two wire system for the lights as some clearance
lights come with two wires, and some one.
Scott
> I am re-wiring my trailer and wondered if anyone has seen the trailer
> brakes grounded on the trailer? It looks like right now they ground
> through the plug, then the wire comes out of the plug under the truck and
> goes to the frame for a ground. What is the usual or industry standard? I
> know some times trailer lights are grounded at the fixture and sometimes
> they ground back through the plug too, is there advantages of one over the
> other? The plug has a ground terminal on it, so they must expect at least
> one ground wire to go through the plug and back to the truck.
> Joe