Thanks for the help. I have been able to fix most problems by reading all of the forums. Yes I have read the ford lighting relay fix but I am still in the dark. This truck is an 89 f350 with 94 powerstroke drive train. 7.3 and a 5 speed. It all started the other day when I had a lowbeam go out. I replaced both headlight bulbs with the stock bulbs. That same day my dash lights and taillights went out. They blew the outside lamp, map lamp, instrument illumination (#4?) I still would have headlights and turnsignals just no tail or dash. I replaced the fuse and it was fine for a day or so. It blew the fuse again, and again. It got to the point where as soon as I would turn my lights on it would blow, still keeping the headlights though. I tore the dash apart and found the plug that goes into the light switch was melted along with some of the wires that go into it. I replaced the wiring, plug, and switch. I hooked the batts back up and tried it. Everything worked but no head lights nor tail lights. The fuse was fine though. About 2 mins later, the fuse blew (#4). I thought I might of fried the dimmer switch. I checked the continuity and it was all good with the switch. I checked for power into the switch (red and yellow wire) and I had power, but it was flashing out of control. When I was doing this, I noticed there was a wire in the harnes where it goes trough the firewall. I pulled the plug apart and inspected it. Everything was ok with it. I replaced that wire (#12, hot wire from light switch to the front marker lights) and ran it separately out side of the plug. I replaced the fuse and tried it again. Now, still no headlight. when you pull the switch out for tail lights, the driver rear turnsignal bulb lights up solid. The brakes work correctly. I very well could of fried the new light switch. I went and bought the last one in our small town. I havent tried it yet. I have correct continuity on the head light, marker, and tail lights. On top of it, I pulled every single bulb, head, tail, brake, etc (including dome, glove box, and cargo) unplugged the turnsignal switch, and still when I pull the switch on, it blows that fuse instantly. Any help would be awesome!!!! Thanks !!!!!!!!

 

If you had an ohm meter you could check wire going out to the bulbs as long as they are unpluged or check them at the bulb with switch off. High readings indicates a direct short to ground. next follow that wire to the problem. Most often it is at the rear of the truck between the y from main wiring harness to the seperate tail lights. You can find cheap multi meters for under 20. bucks in the household wiring section at home depot or sometimes wally world.

 

You might find more help in one of these forums.

https://www.ford-trucks.com/forums/forum28/

https://www.ford-trucks.com/forums/forum117/