Farmall Wiring Schematic with New 3-Position Switch

Anonymous-0 · Dec 23, 2008

There's been a lot of battery charging issues lately and with some help from Bob M., I'm offering this schematic that includes the newer 3-position switch on the market. This replaces the original 4-position switch that was used with a cut-out. So if you are using a Voltage Regulator, this diagram will get you going. Thanks, Ken

ScottyHOMeY · Dec 23, 2008

Thanks, Ken. I'm afraid I've been a bit of a Gloomy Gus about these new switches. I bought a 4-position one and never could sort it out and get it to work on a cutout relay.

Your research and the diagram will be a lot of help to folks, I'm sure. I've got it saved.

Andy Motteberg · Dec 23, 2008

Thanks for posting this!

boomer22 · Dec 23, 2008

Yes thank you it is gonna be very helpful to many, along with Bob's diagrams.

Fixer · Dec 23, 2008

Kendog Just a question about three position switch wiring. AS I look at it the ignition switch in your diaghram isn't fused. Maybe I'm wrong looks to me like switch wire should be hooked to the other end of the fuse. Otherwise great job. Bernie Steffen

Anonymous-0 · Dec 23, 2008

Hi Bernie. Hopefully Bob M. will chime in here as we went around on this - but he explains and understands it better than I. But so far my Farmall-A is behaving correctly.

If it turns out that this requires a revision, I'll be happy to do so. Thank you! Ken

Janicholson · Dec 23, 2008

Almost no ignition is fused. It would make light issues into walking issues. I believe in putting a fuse link (of 10% more than generator/alternator max output) in the primary supply wire linking the amp gauge to the battery (usually at the starter sw/relay) but a resettable 10 amp circuit breaker could be put into the ign circuit as long as it was accessable to reset. JimN

Bob M · Dec 23, 2008

VERY nicely done Ken. I am humbled by your graphics(!)

Bob M

Bob M · Dec 23, 2008

Ken/Bernie - That's how the fuse was wired on the original switch - to protect the light wiring from a short, but not the ignition.

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As Jim N points out ignitions are never fused. (At least I've never run across a fuse in an ignition)

Also as Jim notes a blown fuse in a lighting circuit will just make things dark. But a blown fuse in an ignition can mean a long walk home(!)

Anonymous-0 · Dec 24, 2008

Good morning Bob. Please review the comments below as there are some questions about the fuse placement (you and I have been through this), and maybe you could justify anything needed. Thanks - Ken

Dave in CT · Dec 24, 2008

Thanks for the great diagram. From what I've read in the posts, it looks like many of us have used Bob M's wiring diagram repository as the gold standard for our wiring -- 12V conversions, alternator setups, etc.. Perhaps you could give Bob M permission to store a copy of this diagram with all of his other diagrams (if he is inclined - I don't mean to be presumptuous). Then we'd have them all in the same place. Just a thought . . .

fventura · Mar 19, 2009

Hate to drum up an old post, but I am trying to use this same wiring with one difference. I have a magneto and no headlights on a Farmall A.

My F terminal on my regulator is grounded until I start the tractor. If I jump the F terminal on the regulator to base of regulator it does the trick.

I am wondering if their is a function of the regulator to vary the resistance to ground of the F terminal based upon the load on the L terminal of the regulator and in my case it"s an open circuit.

Does this make sense?

Farmall Wiring Schematic with New 3-Position Switch

Anonymous-0

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Andy Motteberg

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boomer22

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