Trailer lights.. HELP

[Dakota_Rookie]

Bought a cheap boat to start getting the family out on the water, do some fishing and maybe use for some access to hunting spots.

The trailer required new lights so I installed some brand new LED lights and had them all working. It took me a while to figure out my grounding situation but finally got them working and running. That is until I tucked the loose wires away into the front of the trailer, wrapped some electrical tape around the exposed harness and hooked up the trailer to pull out of the garage.

I’ll try to explain current situation to the best of my ability and attach photos to hopefully clarify.

Typical 4 pin flat plug in

White wire - ground
Brown wires - running lights (right and left)
Green wire - right turn signal and brake
Yellow wire - left turn signal and brake

I thought maybe it had something to do with trailer being hooked up to truck so I disconnected again and that didn’t change anything.

I have power at truck connection as checked with test light, light connected back to truck frame.

Plugging trailer wiring harness into truck I have power at the tongue as checked with light on brown wire.

I lose power where the green/brown and yellow/brown break out of the main tongue member of the trailer and into the left and right members.

I still have power here with my test light when I connect light to the tongue member but not when I connect test light to side members.

I have absolutely no lights on left trailer light.

I have only very dim running light at right trailer light.

Again, I had everything working well and lights were bright and checked multiple times until I got cocky and thought it was done.

Can someone help me trouble shoot the issue? I’m assuming a ground issue but i dont know what i did to change them from working to not working when I didn’t change any ground connections.

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[Yoder]

Put the trailer on the hitch. Sometimes the ground isn't great and just connecting the trailer to the truck will fix it.

 

[huntsman22]

redo the rusty trailer ground......

 

[hiker270]

90% of the time trailer light issues are the ground.

 

[displacedtexan]

Actually connect the trailer. That helps the ground. Like was said, most trailer light issues are ground issues.

What's the truck?

 

[KsRancher]

As mentioned above. It's the ground. I do a lot of wiring on trailers. Biggest mistake I see is exactly what you have there. Instead of attaching the ground from the vehicle to the trailer and then the lights to the trailer. Just run the ground to the lights like the other wires.

 

[Dakota_Rookie]

As mentioned above. It's the ground. I do a lot of wiring on trailers. Biggest mistake I see is exactly what you have there. Instead of attaching the ground from the vehicle to the trailer and then the lights to the trailer. Just run the ground to the lights like the other wires.

That’s what I was probably going to do next. The ground from the plug connected to the trailer is just the way the harness came in the package with two short grounds at the lights themselves.

I’m thinking buy some extra white wire to run the length on both side from each light and splice them together near the plug.

Is that what you mean?

To everyone saying connect the trailer to the truck, as said in original post, that’s where the problem occurred. And I tried multiple times with trailer connected and disconnected to truck hitch


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[displacedtexan]

To everyone saying connect the trailer to the truck, as said in original post, that’s where the problem occurred. And I tried multiple times with trailer connected and disconnected to truck hitch

The only thing that matters is how it acts when it's hitched up.

 

[Erict]

I share a utility trailer with family who always seem to find a way to nick one of the wires, which leads to too much time spent diagnosing and fixing. I'm going to try the new wireless systems next time - you may want to consider them, though they cost more than the old wired systems.

 

[schur7559]

As mentioned above. It's the ground. I do a lot of wiring on trailers. Biggest mistake I see is exactly what you have there. Instead of attaching the ground from the vehicle to the trailer and then the lights to the trailer. Just run the ground to the lights like the other wires.

I will echo this. I went through this same issue this spring and as soon as I ran the ground all the way to the lights it fixed the issue. I’ve actually had to do this on multiple trailers. Almost all issues with trailer lights are ground related.

 

[Steve300xcw]

in a bind we ziptied some glow sticks to the trailer and sent it. Never got hit nor pulled over ......................