I just received a 2012 F-250 where I work equipped with trailer tow package. It has the factory trailer plug, 7 blade RV style and 4 pin flat combined. I need to install an additional plug, 7 round pin as used in the trucking industary. All our trailers and other trucks are set up this way.

I want to do this without hacking in to the factory harness. Attached to the left side plate of the Reese style hitch is a harness that terminates with two plugs. One is a 2 pin plug with one wire white and one blue, the other is a 6 pin plug with lighter gauge wires, unknown colors. Both have blanks plugged in to keep weather out.

Could these plugs be a source for the trailer wiring? If so, where can I get plugs that will plug into them?

Thanks

 

Welcome to FTE and congrats on the new truck!

I'm not sure, I would cut into the factory harness but I am very comfortable with electrical wiring. Maybe a trailer dealership would have a plug for that or at least know where you can get one.

I recently got my gooseneck hitch installed at a dealership in Delaware and they offered to install a RV plug in the bed next to the gooseneck ball. I assume they would not have cut into the harness, they probably have a plug that clips right into the factory harness.

Good luck!

 

Thanks for the welcome!

This truck will be used for plowing snow and exposed to road salt, that's why I'm reluctant to splice in to the factory harness. No matter how careful I am, the salt finds its way into a splice and starts trouble. These new factory plugs are very effective in sealing out the elements and if possible I'd like to go that route.

 

Can't you just use the standard tee behind the factory seven pin plug that goes to a seven pin cord for the plug normally in the bed for a fiver, but instead just put whatever end you need on the wires and run it where you want?

Steve

 

That sounds exactly like what I want to do RV_Tech. Where would I find this T you speak of? I traced the wire from the factory trailer plug back to the frame rail where it disappears under the spare tire. I didn't see any junctions.

 

If it is the same Ford design used historically, the back portion of the seven pin plug on the truck comes off and you plug the tee into the plug and snap the back half back on. That essentially gives you an extension of the OEM seven pin.

eTrailer has the tee as do plenty of other folks.

Steve

 

steve f, just get a 7 pin flat and 7pin round about 18 inches of 7 wire , both male ends put them on and done.

 

Why are your company's trucks set up this way? It's not like your F250 can pull a trailer with air brakes. Is it just for checking lights?

 

Look up a Hopkins Wiring - 47595 adapter.

 

My Reese hitch came with the wiring harness. Unplug, replug, done.

 

I finally had time to crawl under the truck and test the leads on the two plugs I found attached to the hitch side plate and they are indeed trailer wires. I'm trying to see if Ford offers a harness that plugs into them.

RV_Tech, I found the 5th wheel extension you mentioned and I'll go that route if the dealer comes up empty.

Thanks everyone for your suggestions!!

 

Sounds like a plan

Steve

 

I'm not sure that would work since the turn signals and brake lights are generally separate on a 7 pin round. (In my experience that is)

 

lowbed dud's idea would work if you used a 7 pin RV male and 7 pin round female plug. That would have been a last resort for me as it would mean a connector hanging in the wind behind the truck.

I've got this figured out at this point. It turns out these trucks are pre-wired for an additional harness, the plugs I found on the hitch side plate are for a 5th wheel harness. I found a dealer that knew about it and Ford offers the harness through their parts department that's plug and play. It comes with the harness and a Pollak RV plug and bracket that appears to bolt to a pre cut hole, perhaps on the 5th wheel hitch itself. It didn't come with instructions so I'm guessing.

I'll plug in to the factory harness and then wire the RV end to my 7 pin round socket. I haven't figured out how to post pics here or I'd show you all where these are located.

 

Will this work for you ?
5th Wheel/Gooseneck 90-Degree Wiring Harness w/ 7-Pole Plug - GM, Ford, Dodge, Toyota - 7' Long Bargman Custom Fit Vehicle Wiring,Wiring 54701-003

as this will move my 7 pin up into the bed where I want it.