Burned up light plug

94turbocrewcab-lb

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Howdy, so this issue actually occurred a couple years ago and the truck didn’t get driven much once I got the motor pulled

So anyways this was the original light switch the truck came with but it looked like someone was in there before me.

I started smelling a burning electrical smell while driving with the lights on. Kept a happening and my dash lights went out.

I pulled the light switch apart and replaced it with a Napa unit. The plug on the truck side was black and burned looking..but I needed to get going and it worked when hooked it all up again.

I’ve only driven a dozen or so times since then and was just wondering what might have caused it and how common is that?

I do recall my dash lights going out again after the new plug was in and then they came back on randomly during the trip.

Thanks
-the truck is currently apart again..took apart the front axle and replacing seals and ujoints..we cracked the inner axle shafts while getting at the ujoints with the press..so they are on order

Reading the 94naidi posts about glow plugs is disappointing..glow plugs are now common issues now? Multiple in a year!

I’ve still considered selling the truck and just running the Cummins and using my money to put in a new septic!
 

IDIBRONCO

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For some reason, the Ford engineers decided to run the power for the lights through the switch. As they get older and dirtier, the plugs tend to melt like yours did. The best solution is to do the relay mod. Buy a relay kit from Bronco Graveyard or LMC Truck and install it. Or you can build your own. That lets the headlights work without running their power through the headlight switch.
 

rreegg

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Recently came across a video about headlight wiring on an '84 F800 and the electrical is similar/identical to our F-series (least my 88 not sure for a 94). Might be relevant for trouble shooting - I've had issues with my headlights in the past but it was corrosion on the hi/low switch on the floor.

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94turbocrewcab-lb

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So this is what I’d want to get? And probably a new switch plug

 

franklin2

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You can get a new wiring pigtail for your switch, Napa probably sells them. Then you will be good to go for another 30 years like the first one.

The headlight relay upgrade is a good one, but when you take the switch back out, you may notice the headlights were not the problem. Usually the problem is the running light/taillight circuit. There should be a tan/white wire feeding the switch. This is the power feed for the running lights and the dash lights. Sometimes this wire burns completely in two it gets so hot. A relay added in this circuit would cure that problem also, but there is no gee-wiz bang "kit" for that, you will have to wire that in yourself. The factory actually used a relay in this circuit if the harness was installed in a dually pickup.

The headlight switch is fed by several different power sources, one for the headlights, one for the running lights, and another comes back for the dash lights. The headlight switch has several different sections to it, all connected mechanically by the switch knob, but electrically separate.
 

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