HELP Hot headlight switch
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From: Norco,Ca.
HELP Hot headlight switch
1993 F-350 dually, had no instrument panel or tail lights. Checked fuse, prior to a long drive home in the dark. Found an unbroken 25 amp fuse, where a 15 amp should have been. Replaced it, and had working lights. I am thinking switch at this point, started truck to leave, and no lights again, white knuckled it home. Bought new switch, pulled old one, noticed the "pig tail" was burned at the brown and white wire. GRRRR. Had to order new part, installed both, unfortunately/fortunately miss place the nut to secure bracket so it hangs out from under the dash. After a 5 minute drive home with lights on, had to grab a hold of the switch to turn lights off, and burned the $#!+ out of my thumb. This was actually the fortunate part, as I may not have realized the problem if it had been secured behind the dash, and could have had an even BIGGER problem! Needless to say, I can not use the lights until I figure out what is causing the switch to over heat. Haven't changed one thing, headlights, bulbs, no new installs NOTHING! I HATE electrical issues, and have no idea what is wrong, or what I am doing! ANY ideas you men out there, or women, lol. Please HELP! Thanks, E.
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From: Virginia
You did install a whole new headlight plug and the new switch? The headlight wiring and switch usually do run a little warm, and with age the connectors get loose, and this creates more heat. This melts the wiring and the plug, which makes it even looser and hotter till the wire melts in two.
If you put a new headlight switch in, and a new headlight plug pigtail, then you should be back to as good as the factory setup, which wasn't very good. If you haven't replaced the plug, you will need to do this to get back to square one.
If you want to eliminate this problem permanently, there are places that sell relay kits to eliminate the load on the switch, or you can wire up your own relay kit.
If you put a new headlight switch in, and a new headlight plug pigtail, then you should be back to as good as the factory setup, which wasn't very good. If you haven't replaced the plug, you will need to do this to get back to square one.
If you want to eliminate this problem permanently, there are places that sell relay kits to eliminate the load on the switch, or you can wire up your own relay kit.
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Joined: Mar 2008
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From: Norco,Ca.
Thank you Dave F. for you reply and information. Yes I did install a new switch AND plug. I can understand that it will run a "little warm", but warm enough to blister your thumb? Some one else told me to just install it back in the dash, it's fine. I carry a fire extinguisher you know, "just in case", but I SERIOUSLY do not want to ever have to use it. Especially if I thought something could be a problem, but ignored it anyway! Maybe they all do run that hot, I can't hardly believe that though, I mean, inside the plastic dash and all. Now I am tempted to disassemble someone else's, just to find out! I will let you know 
Thanks again E.
Thanks again E.
MSEE
Joined: Apr 2004
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From: Austin, TX
The switch will be warm, but not so warm you can't touch it. That much heat sounds like a short to me. It's possible you got a bad switch, or something has shorted in your wiring elsewhere that is drawing too much current through the switch. The circuit breaker inside the switch is supposed to trip before it draws that kind of current, so my money would be on a bad switch.
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From: Virginia
There are many posts on here with people having problems with the tan/white wire burnt in two. And there are others finding the plug melted. It's a problem with some Fords. They undersized the wiring and the switch a little bit too much.
The tan/white comes from the fuse box. Check and make sure someone hasn't done the tin foil trick or put a fuse in that is too big. If there is a short in this circuit, the fuse should blow. The headlights are fed by a separate circuit, and the fusing was changed throughout the years, with circuit breakers inside the switch, and separate fuses on later trucks.
Unfortunately, even with the correct fuses in place, the tan/white has been known to burn in two.
The tan/white comes from the fuse box. Check and make sure someone hasn't done the tin foil trick or put a fuse in that is too big. If there is a short in this circuit, the fuse should blow. The headlights are fed by a separate circuit, and the fusing was changed throughout the years, with circuit breakers inside the switch, and separate fuses on later trucks.
Unfortunately, even with the correct fuses in place, the tan/white has been known to burn in two.
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