Hey all,

I'm new to the forum, so thanks in advanced for your patience. I recently installed a T-One trailer wiring harness on my 2020 Ranger so that I could tow a camper that I just bought. To keep a long story short.... I royally screwed up the installation of that by watching the wrong installation video. I watched the install video for the Curt wiring harness, which looks identical. I accidentally grounded a wire to the frame of the truck that should have been ran to the front and connected to the battery (yes, I should have caught this... I'm feeling plenty stupid about this mistake). When I hooked up our new camper to tow it home, we started to see smoke and the connector totally fried. The wiring harness had melted wires and burnt up connectors.

So, I ordered a new wiring harness to replace the toasty one. As I begin to rip out the burnt one, I notice that one wire from the harness melted on up into the truck's wiring. It appears to the be the wire that carries the 12v power to the trailer, and the sleeving is totally burnt off (see the pic). I can't tell how far this melted wire goes into the existing truck wiring. All the lights work on the truck, and there are no codes getting thrown. Am I totally screwed and need to have this wiring replaced by Ford? Or do you think I can get away with trying to shrink the bare wire and put the new harness on. I would appreciate your all's opinions here. I'm not an electrical guy.... so you can assume I'm ignorant when it comes to this stuff. Thanks again in advanced.

In this picture, you can see where the harness plugs into the existing truck wiring. On the right, you can see the bare cable that has melted down.

 

Just use a razor knife and cut tape off the "wire loom"

The wire loom used looks like this: https://m.media-amazon.com/images/I/..._AC_SX355_.jpg

It comes in different diameters and is not expensive, recommend using it any time you have multiple wires
This is added to wire harness's at the factory to protect them and keep them together, easy to pull it back or off once the tape at the end is off, and just as easy to put it back on and re-tape

You need to find how far in the insulation was melted and make sure it didn't melt other wires near it, it is most likely OK within an inch or two of the end of the loom, but you for sure need to find out


But what is MORE CONCERNING, is the fact it did this melting at all
Any wire that carries 12volts needs a FUSE at the battery(power) end so it BLOWS before something like this can happen

It could have been 12volt from truck battery or 12v from Trailer battery that caused this, but either way there was NO FUSE.and that needs to be changed
Even alternators have fuses, lol, and they are only 100-150amps
Car Batteries have 500+ cold cranking amps they can release, so.....................fix the wire and FIND or ADD a fuse for that wire, at the power end of the wire


Point of a fuse is to cut power if there is a short to ground, so fuse needs to be as close to 12volt source(battery) as practical, OR the wire between the battery and fuse becomes a fuse

 

I'm no RonD, but it is a black wire, normally 12V DC black is ground !

What is that wire attached to on the other end ?

When did the wire sheathing melt , what did you do when the wire shorted ?

Was the power on in the truck when this happened ?

Last thoughts..., if that wire had been run to the battery... you may have had a fire started, based on the length vs the heat it would have produced.
Remove the wire FIRST, so it won't happen again; verify where it is coming from and where the power is coming from that caused it to melt.
Remember BLACK is ground, if there is that amount of current (amperage) running to it, seems wrong, seems like there is a wire crossed !
Also, do you have an extra battery, use it to verify the harness in the trailer is working properly.

Luck on your search for the power.

 

Yes, +1, he said he miswired a 12v to ground directly, which is a big OOPS, lol

But the melted wire should NEVER happen since all 12volt wires are fused, so he found a flaw in the system's 12v distribution, not sure if its in the Ford system or the trailer system since trailer was hooked up when this happened

You can never have too many grounds
And you can never have too many fuses

When in doubt GROUND IT
When in doubt FUSE IT