Vehicle arrived with no tail or park lights. Customer stated that they work sometimes. As this is a very common problem with almost all Ford vehicles that have a pull knob type headlight switch I went straight to the problem and documented to help others.
First I gained access to the headlight switch. I could see the damage to the wiring from the outside of the assembly. Brown wire was burnt at the top left corner of the first picture.
Unplugged connector from switch and more damage was evident. The switch and the harness had to be replaced.
A quality replacement harness is currently available online from The Electric Connection. I installed the replacement harness connector by first transferring the undamaged terminals and wires from the original to the replacement connector.
After all good wiring had been transfered I only had to replace the one burnt wire and terminal. Sometimes more have to be changed.
I then reassembled to a new Motorcraft headlight switch, tested and reassembled the dash.