Never ever hook up your boat trailer or any trailer pigtail without a proper fuse inline. I decided to be that brilliant and do such and now I am paying the price. Truck has been out of commission for almost a year. What ever box is mounted under the dash with about 2 dozen wires coming in completely melted after the pigtail wires pinched under the trailer ball. Einstein! I went to the junkyard and found a used box and spliced it in. Everything seems to work properly all except the brake lights. I have changed the brake light switch, bulbs, twice. I have no clue what to do next. Should I look at the multifunction blinker switch? Is the box out of the junkyard bad? I have read on the net maybe the ABS sensor is bad? I am just clueless at this point on what to do or how to finish troubleshooting. I almost want to just install a universal brakelight switch and bypass all existing wires. If I had a clue on how to do that I would. Anybody that can help me troubleshoot this and get my truck fixed I will gladly mail you something off my site in exchange for your help.
#dakatohopeless
2001 Quad Cab 4.7

 

have you checked the wiring going from the pigtail to the tail lights?

 

The combination flasher works the stop/turn lights. The brake switch just provides an input to the combination flasher.

Is the CHMSL (3rd) brake light working? That is run directly off of the brake switch.