Hello, this is one of the times that if I can get my wiring fixed because someone actually online can help that would just be another reason the internet kicks ***.
I'm about to flip out not being able to fix a problem. I bought my first Ford ever yesterday (2000 F150 XLT 4x4). It came with a six pin plug hook up for trailers. My daily work trailer is a four pin horizontal hook up so I wanted to either find an adapter or splice in the proper hook up. While trying to figure out which wires did what on the stock round 6pin hook up the only hot wire was tailights.......no stop Lturn or Rturn signals. I followed from the 6pins up to where it had been spliced to the main wires that ran to both sides of the back lights. I followed that until I found a connection were I was able to unplug it and test from that connection......I found power to LT and RT and stop.......but completely lost tailights on my truck...I checked the fuse chart in the manual and for the life of me I can tell what fuse it should be. I does say anything like (parking lights, running lights,) So I unpluged and visually inspected every fuse there was. So now I can't drive at night cause I got no tailights. I was able to splice in the trailer lights to RT, LT and stop. Just enought to be able to drive and work in daylight hours. But I lost tailights and now the dash illumination..........I'm freakin...............can the wires at the back of the truck affect the illumination on the dash.......starting to miss my Chevy. HELP.

 

I had a '94 ranger that all I had to do, was crawl under the truck and find a connection from one taillight to the other, disconnect it and put the trailer connection in between them. It was very simple, unplug, then plug in one side, then the other, then I had my 4 pin plug for my trailer, took all of maybe 2 minutes. I am curious why the previous owner didn't do this, instead of splicing. Maybe that was the only way to get it to work. Hopefully some one else will chime in soon, but the previous owner may have screwed something up if they spliced them in the way it sounds. Good luck and I hope it turns out to be an easy fix.

 

You have more fuses under the hood on the driver's side...check them out too.

 

Walmart sells a converter for the round 6/7 to a four connections. Most trailer/RV sellers have them also. Remember that you have a fuse panel in the truck under the dash, and one under the hood up close to the rear driver's side. Most faulty wire problems can be traced back to improper ground.

Good Luck

 

I had the same problem years ago on my 88. Yes the tail lights and dash lights are on the same circuit. If you find the fuse it will likely be blown. Sounds like you may be the victim of a badly hacked wiring job. It happens. If it were me and I had the money to spend, I would probably replace the entire harness at the rear of the truck and then do the wiring right so that the problem doesn't resurface. It may be a little pricey to get the thing from the dealer but you might look online to see if you can find a good deal.

Good luck!