Ok so I've got a 4-way plug from the factory on my 07 F150 but I want to add a 7-way so when I get around to throwing the Brake Control in there I'll be all ready to go. I bought a Hopkins 7-way that plugs into the factory 4-way and has 4 additional wires to tap. One is the ground no sweat there I got that.

1) 12V AUX just wondering if anybody has a good 12V source back there that is only powered when the truck is on. I don't want my fridge killing the truck battery when I shut down

2) REVERSE same thing just wanna know where anybody tapped into this line I assume it's for Reverse lights ona trailer so I should be able to tap into a line running to my truck reverse lights.

3) ELECTRONIC BRAKE I know this needs to come off the brake control but I don't want to run it all the way up to the dash. My truck has the plug under the for the BC so all I need to do is add the BC and the Relay in the panel just wondering where to tap into this in the back of the truck.

Any pics, Color Schemes, or tips from someone who's already done this would be appreciated.

 

There should already be a 7 pin socket up above the spare tire - all you need is the adapter harness to go from there to your bumper, the harness from under the dash to the controller, and the relays.

 

Right I got that but to get that harness from ford is going to end up costing $180. I can use a universal harness for $27 by splicing into that end you speak of. Just trying to find out who's done it and where they spliced to.

 

I just did this conversion so here goes:

1) You need to buy the relay #5, i got 3 for $30 at ford.
2) Remove the spare tire, crawl under and look on the driver side frame rail. You will see a harness with a connection near the rear crossmember. If you look closely at the connection you'll see an orange wire, and a blue wire that goes into the connector, but does not come out on the other side. The orange is the 12v, the blue is for the electronic brake controller. Cut these and splice them to the adapter you bought. Use a tech screw and ground the white wire.
3) when you install a brake controller buy the vehicle specific adapter, there is a connection for it under the dash behind the diagnostic port. If you have any questions feel free to let me know.

I bought all of ym stuff at etrailer.com, the prodigy brake controller, and harness as well as the 7 pin adapter.
*Note*-the orange 12 volt wire will not have power until the relay is installed. I would suggest looking at the sticky on the top of the page for the relays needed. For some reason my 06 only needed the #5 relay, it had the other ones in already, as well as the fuses.

I would recommend installing the relay and unhooking the connection and testing where the orange wire would be. Just to make sure they didn't change colors. With the key on it should be hot.

 

Thanks everything works that I did. However now I have no left trailer turn signal. At least I assume I don't multimeter to the right side and ground I get 13.9/0.0 as it blinks doing the same thing on the left side I get zip zilch nada just a minor negative draw, my turn signal on my truck still works though. I didn't even touch any of the turn signal wires that was a plug and play portion of the harness any ideas?

 

Check it at each 'connection' of the harness at the back end.

 

Thanks I did I even checked reversing the probes to see if it was a negative polarity deal nada nothing but the truck lights work. I'm wondering if it's just a fluke.

 

Fuses....fuses....fuses

The trailer plug is fused seperate from the truck lighting

 

Thanks for the ideas but none of you got it. I checked the fuses I had all required fuses minus RO5 which is a relay that powers the Brake Control which has nothing to do with turn signals. My right turn signal worked like a champ my tail lights worked like a champ. My truck left turn signal worked like a champ. The only thing I didn't have was trailer left hand turn and left brake on the trailer which are the same circuit. Figured it must be a faulty wire harnes from Hopkins so I start to shoot it, well it had continuity all the way to the truck wire harness. so that's not it. Checked the factory 4-way harness and same thing no left turn on the trailer to the factory harness which I have not cut nor altered. So I decide it's the factory left trailer wire and splice the new 7-way into the factory left truck turn signal and now everything works great. Guess that's what happens when you outsource all your wire harnesses to Mexico.

 

Relay #5 actually powers the 12v accessory. The trailer brakes consist of just fuses.

Glad you found your problem though.

 

fairly certain Relay 5 sends power to the Brake Control not the 12V AUX. I used a buddies truck with factory tow package that does not have relay 5 plugged in to decide where to splice mine into. When I hit 12V AUX with a multimeter I get 13.9V with the truck running and nothing with it shut off. Since I don't have the relay plugged in and the owners manual says trailer tow relay I gotta think it's the brake control relay especially since from the factory the realy comes in a plastic bag with the brake control harness and tells you to install both with the BC.

 

Spliced into the truck turn signal wire instead of using the wiring provided to you from the factory for a trailer harness!

Fuses....fuses....fuses

There are fuses just for the trailer wiring located under the hood. There is no way...repeat.....no way there is a wiring fault on your 2007 truck.

By by-passsing your factory truck-trailer wiring and running it off your truck wiring you risk electrical fire as well as stressing the truck wiring and electronics involved like your steering column turn signal switch ($250), brake accuator switch ($65) and flasher relay ($12).

Find the fuse...put the wiring back like you found it and it will only cost you $0.30 for the bad fuse.

 

https://www.f150online.com/forums/sh...=184757&page=2
Scroll down the page and look at the schematic. Its copied straight out of the owners manual. #5 is the "trailer tow relay, battery charge", AKA 12V accessory.Fuses 105-106 are required for the brake controller. You may want to check your wiring because without the relay in you should not have a 12v hot lead. The reason that ford does this is so that there is not a hot wire not connected to anything, if you're not using the truck to tow. It should be the orange wire that is the 12 volt lead. The blue wire is for the brake controller.

 

Colorado, there is no fuse missing nor burnt out I've already checked. It's not going to hurt a thing back in the days before plug and play harnesses how do you think we did trailer harnesses. Yep that's right splice into the turn signal wires. I've worked on 35 million dollar aircraft for the last 8 years and spliced many many wires into both trucks and helicopters trust me it's fine. Why is there no way that the factory tow harness could be bad is Ford's QA so great that you've never heard of any bad parts getting through?

Red, I'll go out and check but it is hooked up to the exact wiring that the factory 7-way plug would be. Like I said I spliced into the wiring where a factory plug would be.

 

I trust where you spliced into, but i'm jsut curious if you got the wrong wire or crossed the brake controller/12v wire. I just think its worth double checking.