# Trailer light help!



## bigj8145 (Feb 10, 2009)

I put new trailer lights on my trailer and everything works but the brake lights. When you push the brakes the lights go off. Please help so I can finish

Thanks


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## Macgyver (Feb 10, 2009)

sounds like a bad ground, either on the trailer or on the vehicle.


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## ben2go (Feb 10, 2009)

Try attaching a wire from the vehicle to the trailer.Make sure the wire is contacting bare metal.Also make sure the trailer wiring ground is attached to bare metal.Test the lights.If this cures the problem,the trailer isn't grounding to the tow vehicle.Remove the ball and the receiver hitch,if you're using one.Lightly sand everything and also sand inside the trailer tongue.All you're trying to do is make sure there is a clean path for the electricity to flow back into the battery through the trailer frame and into the vehicle's chassis.


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## fishermarine (Feb 10, 2009)

I had this same problem when I wired my trailer because I had pulled the trailer to the truck but did not attach to the ball just hooked up the connectors. I spent an hour checking everything before I realized that the trailer needed to be hooked to the truck for the ground.


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## Macgyver (Feb 10, 2009)

ben2go said:


> Try attaching a wire from the vehicle to the trailer.Make sure the wire is contacting bare metal.Also make sure the trailer wiring ground is attached to bare metal.Test the lights.If this cures the problem,the trailer isn't grounding to the tow vehicle.Remove the ball and the receiver hitch,if you're using one.Lightly sand everything and also sand inside the trailer tongue.All you're trying to do is make sure there is a clean path for the electricity to flow back into the battery through the trailer frame and into the vehicle's chassis.




ALWAYS wire a ground wire NEVER rely upon the ball to ground your trailer lights. you can ground the wire to the vehicle body/frame and then ground the wire to the trailer frame near the tongue. hitch balls get rusted and corroded , they also get greasy .. all of which will not promote a good ground .


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## Waterwings (Feb 10, 2009)

I have no idea about electrical stuff, but I thought one of the plugs on the trailer wiring harness was a ground?


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## bassboy1 (Feb 10, 2009)

Waterwings said:


> I have no idea about electrical stuff, but I thought one of the plugs on the trailer wiring harness was a ground?


It is, but sometimes people don't bother to run that one (the white one, and the only male one on the truck end of the connector, and only female one on trailer end), due to the fact that the trailer will technically be grounded through the frame. The problems here occur when the coupler is bolted onto a painted tongue, or through the painted ball mount and such. Got to have clear metal all the way through. 1 of the other 2 common places for an issue with the ground is any pivot point on a tilt trailer. A grounding jumper needs to be run around that. It is as simple as a 6" piece of wire with a ring terminal on each end, screwed to the trailer in front of, and behind the pivot bolt, with enough slack for the trailer to pivot. Lastly, the issue that many have when reinstalling lights on a newly painted trailer is paint in the mounting holes for the lights, as many sets ground through the mounting studs, or worse yet are mounted in fiberglass. Many higher end LED sets have a 6 or so inch lead with a ring terminal, so you can put a screw into the frame to solve either of those issues.


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## Waterwings (Feb 10, 2009)

I'll look at my harness on the trailer next time I'm out in the garage and see if there's a white wire going into the plug. I haven't had any problems with lights on this trailer or my previous one (knock on wood).


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## bassboy1 (Feb 10, 2009)

Waterwings said:


> I'll look at my harness on the trailer next time I'm out in the garage and see if there's a white wire going into the plug. I haven't had any problems with lights on this trailer or my previous one (knock on wood).


I bet there is. Otherwise, they would have to cut it out, since it is on all light plugs, and while many guys do that when working on their own trailer (how hard is it to run a screw into the frame through a ring terminal?), I can't see a reputable trailer company taking that shortcut. Check your truck end too. If somebody installed the hitch themselves, and you got it used, you could see the same shortcut taken. 

Trailer lights are about the simplest thing to do. What you have to remember is to make sure that the positive lead is connected correctly (color coded - just match them up), and make sure it is pretty well waterproof, and make sure there is a clear run from the ground to the vehicles frame. As long as there is welded steel the whole way, you are good - at points there isn't (hitch, pivot points) make a a wire jumper. The wire jumper at the hitch is the white wire in the plug - just make sure it is connected to the vehicle frame with a bolt or screw and to the trailer. ALL there is to it. If you have trailer light problems, and it isn't covered in this paragraph, it is either a problem with a fuse or broken wire in the vehicle, or a bad bulb/corroded socket. There just isn't anything else that can go wrong with them.


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## Seth (Feb 11, 2009)

I usually take a file and grind off the rust that forms where I mount my taillights. This helps keep a good ground even when just using the trailer hitch and ball as my ground. I've also taken some 14 gauge wire and ran directly from the truck frame to the boat trailer for my ground. That way you don't have to worry about the whether it's grounding out at the ball hookup.


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## Waterwings (Feb 11, 2009)

Haven't checked mine yet (been kinda busy with the weather, lol). My truck came rigged with the towing package from Ford, so I know there has not been any jury-rigging done, but will take a look when I can get outside.


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## bassboy1 (Feb 11, 2009)

Waterwings said:


> My truck came rigged with the towing package from Ford, so I know there has been any jury-rigging done, but will take a look when I can get outside.


You do know I am a Chevy guy right....

Leaving yourself wide open there :wink:


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## Loggerhead Mike (Feb 12, 2009)

> I put new trailer lights on my trailer and everything works but the brake lights. When you push the brakes the lights go off. Please help so I can finish



trailer lights are posative grounded... switch your + and - around

what year/modle truck do you have? some are different than the others



> I have no idea about electrical stuff, but I thought one of the plugs on the trailer wiring harness was a ground?



correct. usually your neg on an aftermarket harness will hook to your posative. dont get your signal and + wire's mix'd up

are you installing a 4 pin connector? or the new style circle connector?

if you cant figure it out give me your year/modle and ill look it up on the databass at work and give you a wiring diagram to go by


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## BlueWaterLED (Feb 12, 2009)

Seth said:


> I usually take a file and grind off the rust that forms where I mount my taillights. This helps keep a good ground even when just using the trailer hitch and ball as my ground. I've also taken some 14 gauge wire and ran directly from the truck frame to the boat trailer for my ground. That way you don't have to worry about the whether it's grounding out at the ball hookup.




Yup, more times than not it is corrosion. Don't forget to check your fuses too. It would suck to try and track down a wiring problem only to find out you have a blown fuse.


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## Seth (Feb 15, 2009)

BlueWaterLED said:


> Yup, more times than not it is corrosion. Don't forget to check your fuses too. It would suck to try and track down a wiring problem only to find out you have a blown fuse.




Glad you brought that up about the fuses. On my Ranger when I first hooked a boat up to it, I couldn't get my left blinker to work on the trailer. Well after concluding that it wasn't a ground or bad bulb from hooking it up to another truck, I checked the fuses and sure enough the one for my left turn signal for trailers was bad. Replaced it and everything has worked great since then.


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