John Deere M correct generator

Kyleenright · Jan 2, 2022

I have a charging problem on a model M tractor. After doing some research I found that maybe this tractor has the wrong generator.
The tractor has the original cutout relay (2 terminals) but I found that the generator only has 2 brushes when I think it should have 3
brushes?
Will this combination of cutout relay and 2 brush generator work at all?
What would be the best option?
By the way it is still a 6 volt positive ground.

James Howell · Jan 2, 2022

[b:654c4848f0][i:654c4848f0]I think it should have 3 brushes[/i:654c4848f0][/b:654c4848f0]

Take a look at the [b:654c4848f0]GENERATOR[/b:654c4848f0] diagram below.

The OEM generator should have 3 brushes.

Hope this helps.

sunsettractor · Jan 2, 2022

Here is source for the correct generator for your tractor.
I have purchase from him and his product and service is fantastic.
3 brush generator

John T · Jan 2, 2022

While it may be possible to make it work, many of the older 3 brush gennys were mated with Cutout Relays while the later 2 brush were with full fledged voltage regulators.

If you work through my Troubleshooting Procedure it may help find the cause of non charging.

John T
John Ts Charging Troubleshooting

M-MAN · Jan 3, 2022

I agree you have the wrong generator but that won't stop it from charging. Unless you are using the lights I don't think it would matter. Generators are expensive so I would use John T's guide to determine the problem, fix it and forget it.

John T · Jan 3, 2022

M Man, you know more about those models of Deeres then I do, but it was often my experience when those non VR Manual Low High charge control systems (Light switch) failed to charge THE SWITCH HAD A POOR GROUND. If he were to use a jumper wire and dead ground the gennys FLD post and she charged, that says the genny itself is okay so better check the switch ground and the wire from FLD on Genny up to switch.

Agree ????????

Take care Happy New Year

John T

M-MAN · Jan 3, 2022

Yep, rust on the switch tang doesn't make a good ground. The dash gets rust under it too. I took the dash bolts out, blocked it up and sanded both sides good and put a good coat of dielectric grease on there.

Kyleenright · Jan 3, 2022

Thank you all for your responses!
So I tried dead grounding the field and nothing.
Then did the motor test grounding the field and applying voltage to the ARM , the shaft turns but when I remove the ground, instead of turning faster as stated in the instructions it comes to a stop!
Took generator apart and brushes are good , no shorts.
What next?

John T · Jan 3, 2022

If the motor test is used correctly, my next suspect is the Field windings are at fault, I've seen them shorted to case or open. The armature can be shorted out also, none of its commutator segments should show continuity to the shaft. On the motor test there needs to be voltage applied to ARM post and frame ground you know...Then start with FLD post also grounded and it should speed up if you remove the FLD post ground.

John T

Kyleenright · Jan 5, 2022

John when you say speed up, is that just a temporary speed gain and then back down?
Because that's what mine is doing.

John Deere M correct generator

Kyleenright

Member

James Howell

Well-known Member

sunsettractor

Member

John T

Well-known Member

M-MAN

Well-known Member

John T

Well-known Member

M-MAN

Well-known Member

Kyleenright

Member

John T

Well-known Member

Kyleenright

Member

Similar threads