Trailer wiring problem

[prbnearnorth]

I have a utility trailer that has some lighting issues. All of the lights were working properly until recently when the left turn signal stopped working. The running lights and right turn signal still work. I connected the 4 pin connector directly to a battery and tested the circuits. The right side lighting works as it should. However, the left side still does not work. When I measured the voltage reaching the sealed light fixture, it measured just over 12 v. So power is getting to the fixture. I swapped the right and left fixtures and the left side still does not work. I connected the left side light fixture directly to the battery and the lights work, so seems to be a wiring problem. What I can't figure out is why the lights don't work when I have 12V entering the fixture. I bought a new light and put it in but it still does not work. The trailer grounds must be okay because the other lights work. Any ideas? Thanks.

 

[Lvthntitall]

It could still be a ground issue, I would clean all the grounds and see if that helps. There is probably a ground up front and one on each of the back lights as well.

 

[prbnearnorth]

There is a ground on each light and I did clean this. No change. But this is a tilting trailer and there is a large ground that connects the two parts of the trailer when it is tipped. I have not cleaned that but that will be my next step. I just figured since all of the other lights worked, that ground was not the problem.

 

[rookieforever33]

Run a ground from every light back to the hitch wiring.

 

[Azone]

You have a ground issue somewhere is my guess.

 

[*zap*]

Run a new wire from the plug in to the problem fixture.

 

[prbnearnorth]

Run a ground from every light back to the hitch wiring.

Good idea

 

[Mighty Mouse]

A dedicated ground wire will save you a lot of headache. Relying on the trailer frame to serve as the ground will give you problems sooner or later, especially with a tilt trailer.

 

[wyosam]

Here’s how I’ve found trailer light happiness. When they start getting weird without an obvious problem. I just rewire them from the plug back. It really doesn’t take long, and doesn’t have to be done often (well, except maybe for saltwater boat trailers). I almost always find the problem in the process, but would spend more time chasing the problem than it takes to just start fresh. No frame grounds, and sealed lights only.


Sent from my iPhone using Tapatalk

 

[prbnearnorth]

Run a new wire from the plug in to the problem fixture.

A new ground wire or a new power wire, or both?

 

[Steve300xcw]

I'd run a jumper hot wire and see wtf happens. Still dead, you know its a ground

 

[*zap*]

I would run both from the plug in. No routing just lay them on the ground

 

[Steve300xcw]

4 Pin plug kinda says this a hobby lobby special. But, how much of a trailer is this? Chances of a junction box somewhere?

 

[HairyScandinavian]

Down here in the salt trailer lighting issues are almost always ground related. Lots of guys are installing the round plugs and running everything all the way back to a junction box and skipping any grounding with the trailer frame altogether.

 

[Dakota_Rookie]

Run a ground from every light back to the hitch wiring.

I had to do this earlier this year to a boat trailer. Only thing that ended up working. Works great now rather than relying on the trailer to be one big ground wire


Sent from my iPhone using Tapatalk

 

[average]

Wireless trailer lights are pretty reasonable, will be my next investment when my trailer lights decide to act up

 

[Steve300xcw]

We once made a 3am mad dash for the boat ramp with glow sticks hanging off the back of the trailer.....

 

[The Guide]

Wireless trailer lights are pretty reasonable, will be my next investment when my trailer lights decide to act up

This is the way. Magnetic rechargeable wireless trailer lights. No wires to get futzed up and you take them off before you launch the boat or when you park the trailer so they don't walk away. If you can't get way from wired lights due to the distance you haul, use 12 or 14 gauge wire and not the size 22 that comes with so many trailer light kits and run a dedicated grounding wire all the way to each rear corner.

Jay

 

[Wrench]

Ohms are easily measured.....

 

[Frozenlead]

I have a utility trailer that has some lighting issues. All of the lights were working properly until recently when the left turn signal stopped working. The running lights and right turn signal still work. I connected the 4 pin connector directly to a battery and tested the circuits. The right side lighting works as it should. However, the left side still does not work. When I measured the voltage reaching the sealed light fixture, it measured just over 12 v. So power is getting to the fixture. I swapped the right and left fixtures and the left side still does not work. I connected the left side light fixture directly to the battery and the lights work, so seems to be a wiring problem. What I can't figure out is why the lights don't work when I have 12V entering the fixture. I bought a new light and put it in but it still does not work. The trailer grounds must be okay because the other lights work. Any ideas? Thanks.

If it’s a standard 3 wire taillight you will have a taillight, brake/turn and shared ground circuit.
- running light works = ground working
-brake light works but no turn = truck side issue
-no brake/turn = power wire issue from plug