over the weekend while driving out of town im my 93 f350 the headlights and tailights kept shutting off and if i mess with the switch only the headlights or marker lights would work.

I stopped and replaced the switch and it still does the same thing. Is there a relay under the hood or anything?


It did do it last december, but a new switch then took care of it.

It also does have a western unimount plow on it also that has lost power to the headlights too but has marker lights.

 

I would guess that you either have a problem with the aftermarket replacement headlight switch or with the wiring that was added for the plow lights.