Need help wiring a Farmall H

ZB Hay Farm · Sep 26, 2010

Need some help on a 1940 Farmall H. Bought in the midway restoration phase. A 4 wire harness is hanging there, one wire to the mag, one to the starter solenoid, one to the battery, and the fourth is just taped up and tucked away. It is going to a two sided push button switch. Looked at the book I had for old farmalls but they do not have a diagram. Should the mag wire go to ground, the solenoid to the voltage side. The battery wire already runs to the voltage side of the battery, Does that sound right? If I touch the mag and solenoid wires together I get it to turn over. By the way it had a 12 V battery in it, folks told me that will work fine to start it. Thanks.

Janicholson · Sep 26, 2010

Well lets make sure the mag does not get damaged. Do not connect the mag to anything with power in it.
It is grounded to stop the tractor, and the ground is removed to run. More to come. Jim

Janicholson · Sep 26, 2010

The following diagrams will work for stock 6volt wiring, and 12 volt with an alternator but battery ignition, or with a generator. Choosing the correct diagram is important. There is a different diagram if you want to convert to an alternator It shows how to wire the alternator excite wire with a mag.
Do not assume the wires now connected are correct at all.
The mag ignition button should have one terminal. It should be connected to the mag terminal only. The mag switch is internally grounded to the switch body, and thus to the electrical box, and ground through that.
If it has a two terminal push pull ignition button, it can work for the mag if its second terminal is grounded, and no other wires are attached except to the mag. It will work backwards, pushed in will be on, and pulled out will be off.
Best of luck they are great tractors, and we will be here for you. Jim
Bob Ms Superlative Wiring diagrams

Tyler Jackson · Sep 26, 2010

The only wire that should be comin from the mag is the kill wire. It goes to the on off buttin down by the choke about level with your shins when driving. The battery should be hooked up to a 0 or 00 guage wire that goes to the pushbutton. If you're looking at the back i believe it's the right post. the on the other side of the pushbutton there should be another 0 or 00 guage wire thst goes over to the starter. that should get it to turn over. Now to get power to the switch box you need a 10 or 12 guage wire that goes from where the 0 or 00 guage wire hooks up to the back of the pushbutton on the battery side. They share the same post so oyu can get constant power for the lights and charge the battery. Also you scn use a 12 volt and youll be fine just don't turn on the lights ull blow em. good luck

Tyler Jackson · Sep 26, 2010

Also just incase there should be a 0 or 00 guage wire that grounds the battery with a long bot that goes into the bell housing behind the engine. just incase you didn't ha. it made me think when you said it turned over when you hoooked u the mag wire to it

gene bender · Sep 27, 2010

You have a huge mess first there wasnt any starter soleniod on any H. The wire going to the mag goes to single pole sw which is ground when sw is closed. What kind of a generator and regulator do you heve. No wonder you cant find a dia for your system better just start opver and rewire one thing at a time. You must not have a meter or you wouldnt have touched the mag and sol wire together. Your advise was also bad you need someone who does realy know what they are doing. These things happen all the time redoing wiring gets real messy pput it back to original and then it will work as i did when it was new.

Need help wiring a Farmall H

ZB Hay Farm

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Janicholson

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