M ignition

Terry Smith · Oct 28, 2008

A friend has bought a M and is having some problems with the wiring and has these questions.

Is it a positive or negative ground?
6 volt or 12 volt?
Can a Alternator have a external voltage regulator?

Any help would be appreciated

Janicholson · Oct 28, 2008

It can be any of the above.
The unit was sold as Positive ground 6v with generator and either a voltage regulator if 49 or newer (not sure on exact break date) or a 4 position light switch that manually regulated the charge rate, and a cutout relay.
If it has an alternator, it is probably 12 volts, and it can have a voltage regulator seperate from the unit. Many early alternators were made like that including all the major auto manufacturers. If it is not working, Use the following link to get it right. JimN
Bob Ms wonderful diagrams

rustyfarmall · Oct 28, 2008

6 volt positive ground from the factory but that could have been changed in the 60 plus years the tractor has existed.

Older 12 volt alternators DID have external voltage regulators.

Andy Motteberg · Oct 28, 2008

Check out Bob's wiring diagrams, they are very good diagrams.
Bobs Wiring Diagrams

M ignition

Terry Smith

New User

Janicholson

Well-known Member

rustyfarmall

Well-known Member

Andy Motteberg

Well-known Member

Similar threads