Trailer Lights Not Working

[powerscol]

We have all been in your shoes. You never learn anything without trying. Glad you got it figured out. I do agree with the other posters to just re-wire the trailer - its fairly simple. I suggest you run your wires in some sort of protective covering, and things tend to get rubbed on and shorts happen. If the trailer has electric breaks, be sure to check the break away switch and on board battery.

 

[Al 2]

As others have said, a poor ground causes all kinds of problems. When working on trailer lights I use on old extension cord (any wire will do) and clip on end on the ground on the battery and the other end to where ever I'm working for my test light. This way I know I have a good ground for testing.
Al

 

[PILOON]

The major portion of trailer lighting problems ends up being bad ground, next is probably corroded connections usually hiding under some electrical taped splice.
If you want trouble free splices soldered or crimped but with heat shrink sealed sleeves is the way to go.
Another common problem is wiring that hangs loose underside and gets snagged by road trash.

Once you have assured a good ground, smear grease, Vaseline or some brand of dialectical grease to prevent corrosion.

 

[newbury]

And then there's always the "intermittent" problem.
My trailer break lights didn't work. Turn lights were fine. Checked ll the usual stuff, double checked all the grounds. 7 way tester in the vehicle plug showed everything working fine. Checked the wires from the trailer plug back, all worked. Plugged it in, they didn't.
Disassembled the vehicle plug, one blade connection had broken, when the tester was pushed in it worked. If you put the trailer plug in the weigh must have been enough to tip it slightly, breaking the connection inside the plug

Replaced the vehicle plug, everything worked.

 

[2458n]

Your fuse may have been fine until you plugged in the trailer with the multiple wiring. Pop went the fuse so the newly wired trailer did not work. Great learning process. Harbor freight has the wiring harness and magnetic lights for 7.99. I use a good set to get my auction junk home.

 

[crazyal]

I always weld stainless steel bolts (usually 1/4-20 x 1") next to each light and where the trailer connector ground connects to the trailer frame. Since trailer lights always use the mounting studs to ground themselves and the steel they mount to rusts trailers always seam to have problems. I just put a short section of wire from the mounting studs to the stainless bolt with a little grease in them to help keep them and never had an issue with grounding for lights or brakes. You could run ground wires from each light and brake back to the wire harness but that could mean a lot of extra wires.