TC Ground Issue

Thanks for all the responses.

Sorry for the confusion. There is no converter. These lights are like nothing I've seen before. 40 year old technology I guess. The lights look like normal 70's style household ceiling fixtures with two button switches on either side. Two regular household light bulbs. One bulb is connected to 110, the other is 12 volt. If connected to shore power the 110 side lights up with it's own switch, if running off the truck battery (dedicated battery is in the plan) the 12 volt side lights up with it's own switch and if both are connected you get a double light fixture. They are in good shape and original and cool so they are keepers.

The 110 (just realized in my original post I was dyslexic, typed 120) is like you said grounded on the front tie down. The bus bar is actually in a breaker box with three breakers. I believe the 12 volt was also tied into this via a clamp on the copper plumbing which went away as part of the gutting.

Yes the 7 to 5 is grounded from the truck. I just built the cable and it is working as it should. I attempted to ground the way it was previous inside the camper and I think I understand what's going on after taking some of the running lights down. The screws mounting the running light base to the camper were severely rusted. There is no way a good ground could be made in the state they were in. Fixtures are indeed single wire no ground. Grounded by the mounting base. I did like AnEv942 suggested and tested a couple of the upper marker lights with a dedicated hot and dedicated ground and they light up. I think the answer is going to be running a ground to each marker light and tail lights and all should be good. Easy since there is no walls or ceiling. Thanks again for the help, having no chassis was really throwing me off.

Sure sounds ground, if brake (sig) is looking for ground-(traveling out the dual filament bulb-via tail light wire-common). I assume fixtures are single wire-no ground wire. I dont know how 'gutted' camper is but if walls open running a ground wire is best. Connected to the incoming ground lug.
Grounded thru skin, 40 years ago probably worked ok-. At minimum Id try to get a ground wire to taillights.
If you cant get to marker lights, walls intact, I guess it would be pulling/cleaning ground connections and fixtures. To save grief I'd use a known good fixture to test at each location. More than likley not only bad connection where each light is mounted but probable corrosion in the fixture bulb socket itself (or burnt bulb). Once you have known good +/- at location then address the old fixture or replace.
I do have a sort of unrelated question-but how you described (leaving 12v lights when not on shore) does this camper have AC lights?

It sounds like a bad ground in the truck to camper.Do you have the ground wire hooked up from your 7 way to the 5 way? Ground the truck to the camper with a jumper cable or wire if it works then you know it is the ground. Some thing to try any way.

The negative or ground side of your 12 volt system is probably tied together via a bus bar which in turn is grounded to one of your front tie downs. The other tie down should be grounded to a different bus bar for the 110 volt AC side. This is how my camper grounds are wired and is probably how yours is, too.

My camper has an aluminum frame and the 12 volt ground/negative side is tied to this, too.

Maybe I misinterpreted what you said. You might reconsider keeping the existing converter even if it's working since you've got everything exposed. The newer 3 stage battery charging capability of the new converters really helps batteries last longer.

Had the same problem with my 1970 Amerigo.
Ran a seperate ground to each light
This solved the problem

To avoid electrolysis and corrosion, it would be a better idea to run separate 12V grounds to all the lights. Aluminum siding + steel screws + electricity + road salt = electrolysis!!



The 12v panel or battery could get a ground tie, but don't make that the primary ground for all of your electrical.

Just my $0.02.