horse trailer wiring


Old 08-29-09, 07:46 PM
Thread Starter
Join Date: Aug 2009
Posts: 2
horse trailer wiring

I have an 84 Shelby horse trailer that someone messed up the wiring on. I want to repair it so I can use it but I'm confused by the mess I have to work with.

My plans are to put a 6 way plug on it and rewire the brakes back in so they work again.

We were assured the brakes worked until after we paid for it when we discovered the 4 way set up that had a 7 way adapter hooked up.

Here's a pic of the mess.

Best I can figure out so far is:

Red wires which I'm holding (faded to pink) = brake wires

Green = left turn and brake

D. Green = Left Lights

Yellow = Right turn and brake

Brown (yellow/brown extended with yellow/green) = Right Lights

White = ground which is also hooked to the brake wires from the plug.

Problem I'm having atm is when I rewire with a new 6 way plug which "Red" wire is the "Hot" wire and which is the ground? Or is these supposed to be separately colored wires?

Last edited by rockinmomma; 08-29-09 at 08:48 PM.
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Old 08-29-09, 09:58 PM
Join Date: May 2006
Location: Iowa!!!!!
Posts: 3,779
The hot for the brakes would be a different color than the ground for the brakes.

Different manufacturers have a number of things for the color coding of the wires and ran the wires in different configurations.

You can do the brakes as a single hot wire (from your controller) going to the trailer and branching off to each of the 2 or 4 brakes and the ground for those brakes coming away from the magnets and merging with the lighting ground. Then take that wire back through the plug to the towing vehicle frame or all the way back to the battery. A number do the latter to get a better ground.

For your lights, you would only need one wire for your running lights coming through the plug, then branch that off to all the tail lights and clearance lights. You can do that as a side by side or all the same color - whatever you like. Most of those lights would either be grounded to the frame or merged with your brake ground to be taken back to the towing vehicle.

All that would be left at this point are your brake lights/turn signals coming from the towing vehicle = one hot wire for each side respectively and the grounding - either to the trailer or merged with the grounding going back to the towing vehicle.

Now, are you towing with a vehicle that has the third brake light and are you charging a wet cell breakaway battery from your towing battery?
Old 08-30-09, 09:20 AM
Thread Starter
Join Date: Aug 2009
Posts: 2
Sorry trying to resize the picture. I got a better pic of the brake wires and found that I have a black and red but 2 red wires are connected to those that run to the front.

I've tried finding the makers but can't seem to find Shelby trailers to contact them about their color coding so I'm going off what I can find.

Thank you you've been a great help.

To answer your questions yes (will I need to make any changes for that?) and yes although I need to have the old battery replaced.
Old 08-30-09, 10:45 AM
Join Date: May 2006
Location: Iowa!!!!!
Posts: 3,779
The two red are "probably" two hot wires running to brakes and back to the controller. You need to check that to make sure, though. Then the black could very well be the ground for the brakes. When the wires come out of the axle beam like that, it's a good assumption. Just for information, though, on a brake magnet you can reverse the ground and hot wire and they'll work the same. They are what you call "not polarity sensitive". But in your case don't get into swapping wires around.

There are a lot of the old sixties and seventies trailer manufacturers that have gone out of business.

The wet cell charging system is best done by a voltage regulator. That is something you can get from a camper dealer.

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