Trailer Light Issues
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Senior User
Joined: Aug 2003
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Trailer Light Issues
I have a 2004 F150 FX4 and every time I hook up my trailer lights I blow the back up light fuse #10 on the fuse panel. Any ideas where to start? It happens with my 7 pin and 4 pin connections.
FTE Legend
Joined: Jul 2005
Posts: 65,938
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From: Millersville, MD
No matter, if you are blowing a fuse, there is a short in one of the two vehicles....the trailer is most likely. Have to tried hooking it up to a different truck?
You need a volt/ohmmeter to test either circuit. Key off, trailer disconnected from truck. Check for a short to ground at what you think is the brake light circuit of the trailer. If you find a "0" ohm reading on the meter, where it should powering a lamp, you found your problem.
You need a volt/ohmmeter to test either circuit. Key off, trailer disconnected from truck. Check for a short to ground at what you think is the brake light circuit of the trailer. If you find a "0" ohm reading on the meter, where it should powering a lamp, you found your problem.
Thread Starter
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Senior User
Joined: Aug 2003
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As soon as i start the truck with trailer hooked up i hear the fuse pop, but as soon as i disconnect it and start it, it doesnt pop.. I also tried my 3rd brake light that is under my trailgate and as soon as i plug that thing it, the fuse pops too. and it does it with my 4pin and 7pin
FTE Legend
Joined: Jul 2005
Posts: 65,938
Likes: 1,432
From: Millersville, MD
Then I would start here: https://www.ford-trucks.com/forums/5...g-diagram.html
Check to make sure a previous owner didn't switch some wiring around. This is the way it should be!
BTW, look at the top of this Forum for a great set of hints and instructions for trailers and towing.
Check to make sure a previous owner didn't switch some wiring around. This is the way it should be!
BTW, look at the top of this Forum for a great set of hints and instructions for trailers and towing.
CO River Rat
Joined: Feb 2004
Posts: 3,209
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From: Lake Havasu City AZ
Because it pops when you start the truck, it sounds like the 12vdc pin is shorted and taking the center (back up) pin with it. The 4-pin socket has no 12vdc or back up circuit so if the #10 fuse pops when you plug something into it, you've got a serious TV wiring glitch. Like BP said, it's time for a multimeter.
Steve
Steve
