I added a 7:4 trailer plug last night to my 99 Superduty. It did NOT come from the factory with the towing package. Do these trucks have the electronic brake controll and battery charging wire already plumbed to the back?? I wasnt sure since it didnt have the factory tow package. I have a plug and pigtail that is wire tied up at the back. It has 4 wires coming out of it...White
Green
Yellow
Brown

I thought these were for the 4 pin plug but the only wires I could get any power off of was the brown wire. I just spliced my trailer plug into the tail light plug

 

I don't think its "plumbed" for anything... My girlfriend's ranger's 4 pin is connected to the factory tail light wires.. I don't know if the superduy is the same or not... But I just ran an extra power wire from the battery to supply the "battery charge" wire.

My F-150 with the towing package has a separate set of wires just for the trailer lights. They have their own fuse etc... Hope this helps...

I bought a nifty device from NAPA that taps into your brake/turn/running light wires. It monitors the wires, and when one lights up (eg turning signal) it supplies the correct wire with power. It's hard to explain, but in essence, it has its own power supply, and it doesn't pull any load on your truck's wiring harness... (For use with a trailer that has a lot of lights, that might potentially overload the factory wiring)

 

Alot of people have said you can just plug a harness into a plug under the dash for your brake contoller so thats why I was asking about the wiring at the back.... Thought the wires might already be there for the brakes and such.

 

That would be true except that your truck doesn't have the wires running to the front of the truck. (I think). Maybe somebody with more knowledge than me will chime in. If nothing else, you can just run a wire. It's really easy, and you will be able to troubleshoot it yourself... Just be sure to run it through conduit, and zip tie it every foot or less. You don't want them to vibrate a bit. If you leave wires loose, they will vibrate together and wear through.... You don't want this to happen, I assure you! When I ran the wires for my girlfriend's ranger, and for my strobes, I just followed the OEM wires and ziptied the new ones to the outside of the OEM harness. Works great!

 

All superduty's are pre-wired....in fact anything 1997 and newer F'series even the F150. They may not have the connectors that go to the bumper, but the harness is equipped.

Somewhere behind the axle in front of the rear bumper is a wire connector or 2 depending on the model. Some are tucked up behind the bumper and the spare tire. One will have brown, green, yellow and white wires for a 4 pin set up or have 8-9 wires in a bundle plug. If it only has the small plug...look for another plug with 4 more wires. They will be blue, white, red w/ green trace and orange. Now you have everything you need to wire the plug under your truck......oh yeah, by the way, if you get the harness and connectors from Ford for the 7 and 4 pin it will plug right in.

Here is a break down of the ford wiring harness colors and what they are:
Brown---running/park lights
Yellow---Left turn/brake light
Green---Right turn/brake light
White---Ground or Neg.
Orange---12v.+ auxillery
Blue---Trailer brake feed
Brown w/ green trace---reverse lights

The truck will be wired under the dash for a brake controller. It will have a grey 6 pin for connecting to a brake controller. There will be fuses and relays that need to be installed to make your trailer wiring function. Check your owner's manual for each application and year as to what needs to be installed.

 

You are the man!

 

OK...gotcha. Thats what I figured the plug was for however it only had 4 wires coming out of the end of it and all the wires going into the plug on the truck side of it. I could only find 1 wire(brown) with power on it. The yellow and green were dead no matter what I did. I may be missing some relays or fuses for them...I will have to check. My next question is does anyone have the plug that has all the hookups on it?? I need them all for my application so if anyone dosent use the harness at ll or just needs the 4 pin connector I would trade them mine for theirs. any takers??

 

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OK I got it all figured out....I have it all wired up now and need to pick up a couple relays from the parts store. Now I need the factory wiring harness to plug in a brake controller. Does anyone have a spare laying around??