I just bought a Big Tex 70DM auto trailer and I have a question in regards to the 7 way plug on my 2011 F-150.

The trailer has a breakaway box that requires 12v power from the truck to charge the breakaway.
I looked at the diagram on the door to my trucks 7 way plug and it doesn't list a 12v power lead in the socket so I guess my question is:

Does anyone know if Ford has 12v power running back to the 7-way?
It got dark and I couldn't see to test all the terminals with a test light so I figured I just ask here...

Thank you.

 

If you have the same setup as my 2010 standard towing package my F150 has, there are 2 trailer recepticles under the rear bumper. There is a smaller 4 pin trail plug. Both trailer plugs supply 12 volts to a trailer.

 

My 2010 has a pin that is 12 volts hot when the truck is running.The truck came with a relay and a brake controller harness in a bag in the glove box.The relay has to be installed under the hood in the fuse box for the 12 volt terminal to be hot.

 

Technically you are correct. Both plugs supply 12Vdc. BUT The small 4 way only supplies power for lighting. The 7 way RV has terminals for lighting, Brakes, and a 12VDC power supply used to keep trailer batteries charged.

As posted above. There should be a relay in the glovebox that needs to be installed.

 

I was only answering his question, "Does anyone know if Ford has 12v power running back to the 7-way?" The answer is yes.

 

OK, And I was only clarifying that response. You also stated that BOTH plugs supply 12V power. And as said before, both do. BUT only the 7way has a full time 12V power pin in the plug. The 4 way flat does not have such.

Sorry if you took offense. I was merely trying make it clear to the OP.

Also for clarification... Here is a link to a picture of the plug and what each one goes to. this one shows the 12v power pin being the black wire at the top left of the trailer plug. Pollak Black Plastic, 7-Pole, RV-Style Trailer Connector - Trailer End Pollak Wiring PK12706

 

Thanks guys for the responses

I had to get a magnifying glass but I found the terminal in the plug on the truck... It is shown just as a "+" so I missed it the first time I looked. It's VERY small.

For some reason the truck and trailer are not wired the same. The brakes on the trailer are only activating when I manually activate the trailer brakes on the dash and I only have power to the break-away charge wire when I step on the brakes.

I guess I'm either gonna have to rewire the trailer to match the truck or take the trailer back and let them mess with it. All the lights work so I think the brake and 12v wires are switched or something.

Thanks guys.

 

PLEASE!! dont rewire your truck!

i'm not sure if you are using an adapter or not, but be aware that some older trailers with the smaller 6-round connecter have the B+ and Trailer Brake wire reversed.

if this is the case, you can simply take the adapter apart and switch the wires, they are built so that they can be switched.

If i were to guess, i'd say you have a combination of a wiring issue and a grounding issue at the trailer ... i'd start there. if you rewire your truck you are going to have trouble with EVERY other trailer you hook to except yours.... save yourself some grief in the long run and make your trailer conform to the standard.

 

Umm, no I'm not gonna rewire my $44,000 truck. I'll fix the problem with the trailer or let the trailer dealer fix it. It's a brand new trailer

 

There you go. That's what I would do as well.

 

F Y I if you dont have 12v or full time lighting (travel trailers only) at the plug when hooked up check relay #9 and fuse #21 to see if thay are blown or not in yet! hey good luck and enjoy

 

Thanks for the info.... Once I found which terminal it was in the plug all works fine now... It's all working.

The trailer manufacturer had the 12v wire and the brake wires switched in the trailer 7way plug... I swapped the two wires and everything works great.

Thanks for all the responses guys!
Jess

 

old trailer? well it must of been if its fixed with the switching the brakes and 12volt wires. glad its fixed

 

The truck came with a relay and a brake controller harness in a bag in the glove box.

 

me too. its a 2006 trailer. not that old

I know it did, however I have the HD towing package so I have the in dash factory brake controller so the relay was already installed when i bought the truck. The harness still sits in the glove box, it's not needed with the factory controller in there.