I have a 99 F-250 SD that does not have a factory trailer tow. I am guessing this because of an aftermarket reese type hitch and the factory plug that only has a 4 flat type connector. I recently installed a brake controller, found the underdash connector and plugged in. I went to NAPA and got the connector for the rear that has the four trailer light wires coming out and a blue and red wire. I figured the blue is the brake and the red should be 12V. I tested the orange wire coming from the truck and it doesn't have any power on it. I also checked the fuse box in the truck and the one under the hood to make sure that all fuses are installed. What am I missing to power the orange wire?? Thanks.

 

Check to see if that orange wire is power for back-up lights, not 12v. Are you using a 6- or 7-pole trailer connector?

Steve

 

Save yourself hours of headache and go but the Ford adapter for your truck I just got one for my 04 F-150 Heritage and it replaces the little flat four prong plug with a 7 prong round RV plug and a flat four prong plug. Very easy plugs into the facotry wiring.

 

I assume the NAPA Connector is the one with the blue and red wires, so you have a 4 to 7 or 4 to 6 kit?

As I understand it, you're looking ti wire up the trailer connector at the back of your truck. Ford runs everything for everyone almost all the way there, actually. If you get the Trailer Towing package, they continue the other three wires (Brake Control, 12V Power, and Backup Lights) to a 7-way Bargman connector. If you didn't get the trailer towing package, Ford ran the wires down your driver's side frame rail down to somewhere near where the spare tire is. There is one main harness and maybe another little harness. Here's Ford's Wiring Convention for you:

Dark Blue - Electric Brake Control Output
Orange - 12V Power Supply
White - Ground
Green - Right Turn
Yellow - Left Turn
Black with Green Stripe - Backup Lights
Brown - Running Lights/Tail Lamps

Now, about that 12 Volt problem. As I put above, the Orange Wire is in fact the 12V + power feed. Do you have your key in the ON position? Power is only supplied when the key is turned on.

If you still aren't getting any power with the key turned on, you're going to have to see if you've got the relays you need. I think the newer Super Duties come with the relays installed, but just in case they don't, you can check by opening up the Power Distribution Box under the hood. If there isn't a map on the inside of the lid to help you out, your owner's manual will tell you where the relays are supposed to be. You need a Battery Charge Relay (and a Trailer Backup Light Relay as well if you want the backup light function to work). It's the same relay number as the neighboring relay is.

 

Thanks guys for the help so far. I am using a combination 4 flat and 7 round plug that you I picked up at Wal-Mart. I believe that it is made by Hoppy. It comes with no plug on the truck end. I unplugged the new connector from NAPA that has the re/blue coming out to check the truck side on the orange. There is no voltage there with the key on. I checked both the fuse box and checked every fuse that was trailer related and checked the power distribution box also for all of the trailer "maxi-fuses". I also have a small box with two relays between the power distribution box and the brake booster. It has both relays in that are the same part number. Is it possible that the one for the trailer power is bad??? If so, can they be tested? I know my father in law had a similiar problem with his Chebbie and he discovered that they put a "dummie" fuse in. I don't want to go out and get the Ford plug because I already have everything and I can't return. What next?

 

The trailer relays should be in your Power Distribution Box. This is a large box, and it has Maxi fuses in there with the relays as I recall. There is a row of similar relays in there. I think there are four of them. Look for empty sockets next to your backup light relay. I think that's where they are supposed to be.

Does the underside of the lids on those power boxes tell you anything? Sometimes they have a little map to tell you what the relays do. Some of the newer trucks have numbered locations that correspond to a key in your owner's manual.

Do your trailer harness backup lights work? This is a separate line from the lamps on the truck itself. It's a black wire with a green stripe in that same harness up in the frame. If you aren't getting power back there when you have it in reverse with the key on, my bet is that you're missing the relays.

 

THANKS CowboyBrett! After 2 hours of searching the internet, you provided exactly what I needed to wire in a 7-pin Bargman connector in the bed of my 05 F250 for my 5er to the 7-pin factory plug on the bumper. All I needed was the Ford wiring info (color scheme) which I could not find ANYWHERE else.

 

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