Farmall H 12 conversion with magneto

Alduckcountry · Jun 17, 2019

Hello all. I recently converted my H to 12 volts. I get 12 volts on the battery when it's running, and my lights dont work. ( I updated the bulbs to 12v bulbs) did I miss something? I've seen posts where they mention fuses, but I dont know if I need it. The light switch is an original 4 (L,H,D,B). Does anyone have a specific diagram of a 12v magneto system, or specifically how to wire the light switch? Thanks in advance!

Janicholson · Jun 17, 2019

This will work. Jim

Alduckcountry · Jun 17, 2019

Thanks Jim. So it looks like I will need a switch of some sort to "activate" the alternator? also i have a 1 wire alternator. Am i correct that the drawing has a wire from said switch to the alternator?.

Janicholson · Jun 17, 2019

With a one wire, you only need to attach a #10 wire from the alt output stud, to the load side of the amp gauge. No other wires needed. From
the big terminal in the diagram I provided, to the amp gauge as shown. Jim

Alduckcountry · Jun 18, 2019

Ok, I have everything wired as your diagram. I am going to check the belt tension on the alternator. As for the lights, I'm still searching as to why they will not work.

Janicholson · Jun 18, 2019

The most common issue with lights is a bad ground. Hook your test light to the battery ground terminal, and (make
sure it lights when you put it to the other terminal) use it to test the wire going to the light housing terminal.
if it lights, the fixture is getting power from the switch, and the bulb is bad, corroded in the socket, or poor
fixture ground. if no light, the fuse might be bad, the switch might be bad, or wires are bad/broken. Jim

charlieu · Jun 18, 2019

When you did the conversion, didn't you switch the wires on the back of the amp meter, 6 volt systems were positive ground and 12v alternators systems are negative ground. The fuse for the lights is mounted on the back of the light switch.

Alduckcountry · Aug 11, 2019

Thank you all for your help. I finally got back to working on this. Turns out I was just an idiot. Apparently you cant charge or get power to your lights if your wire from the alternator isn't on the battery side of the starter switch. Go figure lol.

Ken Hansen · Aug 12, 2019

I was thinking that you might have forgot to replace the 6 volt bulbs with 12 volt bulbs and they burnt out when you turned on the switch!

Farmall H 12 conversion with magneto

Alduckcountry

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Alduckcountry

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Janicholson

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