# Electrical short in a trailer



## AeroBrad (Nov 3, 2005)

I have a 6 x 12 enclosed trailer that I pull behind my Mitsubishi Montero. When I plug up the electrical for the trailer to the wiring harness of the truck, it blows a fuse in my truck. When this happens, I loose the driver side tail light (not brake light) and have no lights on the trailer. I put in a new fuse in, hook up the trailer electrical, and pop goes the fuse immediately.

Any suggestions about how I begin to track down where the electrical short is in my trailer wiring?


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## oldmn (Oct 16, 2005)

Check the yellow and green wire on the trailer plug with a multimeter and replace repair the one that is shorted. If you have the six pin plug on it you may have a short in the plug.
The most common shorting spot on these is where it passes through the frame or body to the back of the taillight.


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## Mullet Man (Oct 9, 2005)

Most likely right at the plug like oldmn said.
You could open the plug housing and look for the short there if possible.


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## AeroBrad (Nov 3, 2005)

Thanks for the tip... I will check it out tomorrow and cross my fingers that the short is at the plug.


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## Volt-Schwibe (Jan 12, 2003)

what i also expect you might find, is that somewhere on the trailer, the wires are rubbed through, and touching the frame of the trailer.

also, i have seen a bulb blow out in such a manner to cross it's arms, and blow fuses.

and, it's a good thing trailer wires are so simple, if worse comes to worse, you could replace the wires on that side, and it wouldn't take more than a couple hours.

i can sketch a diagram of what the wiring looks like if you need.


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## Mullet Man (Oct 9, 2005)

I had a short in an old trailer once. I could not find it anywhere! I hooked a battery charger up to ground, and used the hot lead on each position seperately. When I hit the "brown" wire (marker lights) it let of a sharp spark which told me what circuit it was. I let in go for a few minutes and seen the smoke coming from the bottom of the trailer where the wire rubbed through.

*This was a ******* diagnosis and should not be performed unless plenty of beer is at hand to put out any fire that may occur*


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## oldmn (Oct 16, 2005)

> I let in go for a few minutes and seen the smoke coming from the bottom of the trailer where the wire rubbed through.


Mullet Man 
The only problem with that is after you let the smoke out you had to fix it. :3crackup: 
It's what you call a smoke test.:3-laugh1:


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## Midnight Tech (Dec 31, 2001)

Never thought the smoke test would be used here in the Automotive section...thought that was a computer-only test! :grin:


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## JamesO (Mar 30, 2005)

Open the lights up and pull the bulbs, then connect up. This way you can isolate the problem. You may have the cheaper bulb sockets where the insulator is cardboard and the center conductor pad pulls through the cardboard over time, then shorts out inside the bulb socket. Visually inspect the inside of the sockets carefully!

Also once all the bulbs are pulled, you can use an Ohm meter to test between ground and a wire to detemine which wire/circuit portion you need to inspect closer.

Although I like the red neck smoke test trouble shooting method, if you smoke the entire length of a wire, you will need a lot more beer! You will end up spending more money on the beer than the trailer!!

JamesO


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