Question re: rear trailer wiring

[robertey]

Howdy folks. I'm new to wiring DC stuff. I bought a partially complete teardrop with the trailer, including running and brake/turn lights already wired and working. The interior wiring, a strictly DC system, is separate but also already run and working well. Trouble is, there's no wire for the license plate light. I got one with the trailer, and it's only got one wire ( a black one). How might I go about wiring this in? Is it usually wired into the taillight circuit, and if so, how? I don't need it to get brighter when I brake, which is how I would probably get it if I just winged it.


I searched the forums and didn't find anything that showed how the license plate is wired in.

[Dale M.]

With your one wire license plate light you will need to run a ground wire for it if its not mounted on medal shell of trailer and if shell is not grounded....

As for getting brighter when putting on brakes, it should not.... IT should be connected to tail light circuit and not brake light circuit.... If its wired into correct circuit and gets brighter when stepping on brakes the you probably have a issue with grounding and "lamp circuit" is hunting for a proper ground through "other" wiring and lamps on trailer.....

Poor grounds is a real common problem in trailer wiring because many times the lamp holders/fixtures are designed to ground through their mounting bolts/studs/screws and the lamp holders were designed to be mounted on a metal surface the is properly grounded to tow vehicle.... lamps mounted on wood or fiberglass or any non metallic materials specifically have to have a ground wire added to fixture....

Dale

[robertey]

I was planning on mounting it on the frame, but only because the trailer's not wired to conveniently run the wiring to the hatch and mount it there. I know enough to distinguish the taillight circuit from the brake light circuit now that I know how to do that.

I was planning on mounting the taillights on little brackets or pods on the side of the trailer, but since it looks like I will have to tweak the wiring scheme back there a little bit I think I may go through the trouble of running it through the hatch.

Thanks for your help.

[bobhenry]

I had grounding problems on a tail light on my HF frame and finally ran a dedicated ground and used a mini clamp (tiny hose clamp) and trapped the wire under it as I tightened it around the barrel of the bulb socket.

[angib]

I think trailers should be wired with two conductors going to every fitting and not try to use any metal as a ground. It just causes too many problems.

[Lgboro]

I agree with the separate ground -- it solves most potential problems. I have a neighbor who uses the chassis to ground his boat trailer lights (salt water use) and constantly has problems with grounding / lighting issues. I used sealed led fixtures with dedicated grounds wires and seal them really well with liquid tape and don't see the problems he sees grounding to the chassis. I believe he thinks I am being a smart #@* and wasting wire. One ticket here in NC cost more than a whole roll of wire in the sizes need for trailer lights. The added cost is minimal for sealed led and extra wire.

[bobhenry]

I think trailers should be wired with two conductors going to every fitting and not try to use any metal as a ground. It just causes too many problems.

Dedicated grounding the only way to go in my opinion as well !