Recently picked up a 94 F150 and I can't get the low beams to work. when I very first looked at the truck it had no working lights, I changed a few fuses and all lights worked, the MF switch was in the low beam position, I flicked it to hi beams, which worked but when I went back to low, I had nothing. I have high beams and all marker lights and turn signals, but no low beams. The dimmer switch looks new (not replaced by me) but I have replaced the dimmer switch harness, which had some burning between pins on the old plug. The red/yellow stripe wire coming out of the dimmer switch and goes into the multifunction blinker/hazard/hi-lo/wiper switch is getting extremely hot when the headlight low beam switch is turned on, but not if the high beams are engaged. the wire also twitches to what sounds like a relay clicking and the volt meter jumps, so I'm guessing there's a short somewhere, but where? (it's twisted in the picture because I was trying to jumper it out, but was still getting hot when but connected and shrink wrapped) The maxi fuse under the hood is good, and I've checked the 4 relays under the hood with a working one and still no lights. I've also checked the fuses in the cab, but there's no in-cab for the headlights. horn also doesn't work (not sure if the wiring is shared with some horn circuit or not)
so just to sum it up

dimmer switch appears to be new
multi-function switch is new
dimmer harness is new
fuses look good
red/yel wire is getting hot and twitching
all lights work except low beams
truck doesn't have tilt wheel (no wire pinch point) or daytime running lights
bulbs look good
it does have a 4pin trailer harness
thanks in advance


red/yel wire coming out of dimmer switch
dimmer switch harness
wiring going into the Multi-function turn sig/hi-lo/wiper switch

 

So your low beams worked initially before you first switched to high beams? Otherwise I would suspect both headlight bulbs are burned out on the low beam side. It has happened before.

 

Ya, they worked web I first put the fuses in, but not since, the bulbs look good, the filaments are still in tact, but I'll check them.