Originally Posted by Roy W.
The panel is all 12 volts DC and all wires are black. I have confirmed that all wiring in the panel is connected to the negative side of the battery and that all switches are installed in series with the negative wire. My question is, where can I pick up a positive wire to power the step light. If you don't have a 33 RLDS model you may not be able to answer this question.
What you are describing is a positive ground system. I have one on my 1931 Model A.
I don't believe your trailer actually has a positive ground system though.
The wires may be black in the panel, and the may lead to the black wire on your battery.
But is the black wire on your battery connected to the positive side or the negative side of the battery?
One way to tell is to get a visual on the battery terminals without the cables connected. You then should be able to see a + or a - next to each post.
Why they would use a black cable on the positive side of the battery is beyond me. Although I have seen this done many times in vehicles and boats. So I never assume the color of the cables indicate anything. I look at the battery itself.
Good luck, hope you get it figured out.