# We need help troubleshooting our horse trailer wiring!!



## TDRyan (Aug 6, 2009)

My husband and I just rewired our older trailer today. We have never used it before. After running all the wiring and connecting to the original tailights and changing the marker/top rail lights, we have stumbled across a problem. We got everything to work except for the brake lights. Running lights work, L/R turns work, but when we step on brake- the lights go out. We also changed the top rail lights and amber marker lights, and they are not working. I ran everything into a 7 way plug. Everything was done on previous trailer re-wiring and a diagram. We just can figure out why these few things are causing a problem. On another note, there are wires coming from the axles at the wheels ( I assume for electric brakes). It is a dual wheel axle and both axles have wires coming from them- and they are cut. Now the front axle doesnt have brake drums- why would that axle have wires in it? As I said the wires were cut and I dont think I can splice anything into them, nor do I know how to hook them up. I know electric brakes are usually blue- these wires (looks like 2 from each axle) are stuck together- I assume 1 for ground and 1 to go to plug? please help


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## TDRyan (Aug 6, 2009)

Ok brake lights are working, and turn signals are working. We tapped the marker lights and top light bar into the brown wire to the tail lights, but they are not working. When I turn on the headlights to the truck, the 12V and tail light connections (in the trailer plug) are not lighting up with the circuit tester.


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## JohnWill (Oct 19, 2002)

First off, you need to determine if the lights are individually connected, or the turn signals and brake lights are combined. You may have to buy a converter if the vehicle that you're towing with has separate turn signals and brake lights and the trailer has the combined ones. For the opposite configuration, you'll just have brake lights that also function as the turn signals on the trailer.


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## LauraMJ (Mar 18, 2004)

Have you run a ground wire from the chassis of the vehicle through the vehicle's plug through to the trailer? Then you don't need to depend on the ball to the be ground, which does not work in all situations. If your ground is not right, not solid, you'll get all sorts of strange things like this happening. That is the first thing I would check (and my husband and I have messed with a LOT of horse trailers, lol).


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## K7M (Feb 27, 2000)

If the tow vehicle is factory wired there are separate fuses for the trailer plug. older Fords are under the hood newer Fords are under the dash panel. GMC and Dodge are under the hood near the battery. Consult the owners manual for your tow vehicle. Each circuit is individually fused, left turn, right turn (which are also the brake lights), tail or running lights, 12volt charge and trailer brakes.


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## Drabdr (Nov 26, 2007)

LauraMJ said:


> Have you run a ground wire from the chassis of the vehicle through the vehicle's plug through to the trailer? Then you don't need to depend on the ball to the be ground, which does not work in all situations. If your ground is not right, not solid, you'll get all sorts of strange things like this happening. That is the first thing I would check (and my husband and I have messed with a LOT of horse trailers, lol).


There is much wisdom in that, Laura.:up: I haven't messed with many trailers, but I have messed with a lot of DC control/signal systems. There have many a gremlins that disappeared after *effective* grounding was installed. 

Notice the word effective. There may be _something_ there, but it is not sufficient, which is exactly what I think you were suggesting about the ball.


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## LauraMJ (Mar 18, 2004)

Drabdr said:


> There is much wisdom in that, Laura.:up: I haven't messed with many trailers, but I have messed with a lot of DC control/signal systems. There have many a gremlins that disappeared after *effective* grounding was installed.
> 
> Notice the word effective. There may be _something_ there, but it is not sufficient, which is exactly what I think you were suggesting about the ball.


:up:


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## lisaruss1 (Jun 7, 2009)

sounds like a ground wire problem ive been a mech for 29 yrs,and every one here has fairly good info for your problem !!!


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