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Discussion Starter #1
Hi all,

My '46 B is having some issues with the headlights. This is the original 6 volt system.

When I bought it, one of them worked and the other didn't. I took the non-operational one apart to see what the problem was, and found three things wrong. First, the wire that was formerly soldered to the back end of the bulb had come detached. Secondly, the filament in the bulb itself was burnt out. Finally, the inside was rusty, including the contacts.

So I ordered a new bulb. In the meantime, I glass beaded the inside to clean up the rust. I replaced all the wiring, which still had the original woven cloth insulation, with 14 gauge automotive wire. After soldering everything up (yes, I used rosin core electrical solder), I opted to hook the light up to see if it worked before I re-painted it.

Nope, it didn't work. All the wiring is hooked up correctly and the contacts are clean. I don't know why it won't work. The bulb is brand new.

So I checked to make sure the other light was still working. It was, so I took it apart to verify I had done the other one the same way. Yep, exactly the same. Then I put the working light back, and suddenly it no longer worked. I took it off again and disassembled it to make sure I hadn't knocked a soldered joint apart the first time. Nope, everything was still intact. So now I have two headlights that don't work.

What could be the problem here? There are two wires inside each light, one soldered to the socket into which the bulb plugs, the other soldered on to the back end of the bulb. Given the two wires, I assumed they grounded internally. However, I'm wondering if they actually ground where they bolt on to the tractor. If that's the case, the connection is a little bit rusty (just a little surface rust).

Your thoughts? I'm trying to avoid spending $70 apiece on new headlights when a bulb and a few wires would do the trick.
 

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Ground! The lights are grounded through the light mounts or tractor as you put it. Another way to check to see if they work is run a wire from the light bracket where it would bolt to the mount and touch the other end to a good grounding surface on the tractor. It took me 3 days to get all mine to work. I had to make metal shims to go around the light mount rods so there would be good contact between it and the light fixture. Any little rust or bad contact will keep them from working. They are a royal pain!
 

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Just so happens that I am doing my lights on my 1948 Styled Model B right now. My lights are different from yours. I’m guessing here, but I think a farmer did some barn modifications to yours. None of my lights have wires soldered to the back of the bulbs. There is a spring in the back of the bulb socket that pushes a revit up against the back of the bulb. The other end of the revit has the wire soldered to it (not the bulb). The bulb socket is part of the reflector. The reflector is pressed against the light housing with the gasket and lense hoop. The light housing is then bolted to the tractor.

Electricity goes from negative to positive. Since these model Bs are positive ground, it goes from the battery through the wire through the bulb to the reflector, to the light case to the support post then to the steering wheel support and finally to the transmission case. Each connection must be free of paint, primer, and rust for it to work.
Of course, just to make sure, you can always run an extra ground wire from transmission case up through the steering support out to each light and around the bolt that holds the light on the post.

Lastly, when you get it working, I’d use some silicone grease stuff that they use in modern cars around the bulb socket to keep moisture out but still conducts electricity.

I hope this helps.
 

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Discussion Starter #5
It must have been weak grounds. I cleaned up the contacts and now both headlights work again. Thanks guys!
 

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General rule of thumb: Strange electrical problems are generally traced to bad grounds. Either in the wrong place or non-existant. Wrong place generally burns fuses or wires or something.
 
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