so recently i have been having trouble with my headlights, the turn signals, fog lights, normal yellow running lights and the brights all work just fine but the low beams dont work at all, i figured its got to be the wiring but i am open to suggestion, and also what would eb the best way to find the problem and hopefully fix it. this is in my 91 GT.

 

Get new light bulbs, your headlights in the center have a two stage filament, most likely the low beams are used way more than the high beams and the filamant is going bad producing a weak output.

 

If its not the bulbs than its the switch, a wire may be loose behind it

 

Had the same problem and it was the switch itself. Got a brand new motorcraft part from blueovalindustries.com Was $30 cheaper than the Ford dealer near me.