Need Help From Bob M or others

Ray Heck · Jun 13, 2009

This message is a reply to an archived post by Bob M on December 23, 2008 at 18:58:59.
The original subject was "Re: Farmall Wiring Schematic with New 3Position Switch".

Bob M ,

I am new to the wiring of a 1941 Farmall "M". Purchased it a couple of months ago and and notice the ampmeter never moves. Since the generator appeared to be the issue I had it rebuilt by a local shop that has done repairs for me in the past. The replacement cut-out is different and after I tried it the ampmeter was the same- on movement. OH, also tried the lights and they only work on high and no ampmeter movement. It appears to me the switch maybe bad. What is the next step?
Thanks for any help,
Ray Heck

Janicholson · Jun 13, 2009

First of all The lights working and no amp gauge movement means either the amp gauge is stuck (frozen), or wired incorrectly. The lights should be wired through the amp meter to the starter switch then to the negative post of the battery. Thus when the lights are on, the amp gauge moves. The fact that it does not tells me that you may be in better shape than you thought. With it running at 3/4 throttle or above, test the battery voltage with the switch set at the second position from far CCW. This is the high charge position. It should show about 7 to 7.4 volts across the battery terminals. If it does, you are charging correctly. Turn the switch to full CCW and check the volts. 6.5 to 6.7 are good numbers on Low charge.
Turn the switch to D (third from full CCW) and the voltage should be same as in the High charge position 7 to 7.4 volts. If so this indicates that the light resistor is open (bad) or the light switch terminals are not making contact on Dim.
If the voltage is OK, I would check the wiring against Bob M's Diagrams and if OK, I would replace the amp meter. Let us know what you find. JimN

Ray Heck · Jun 16, 2009

Jim N

Thank You, after a couple of evenings of reading and checking my "M" charges and discharges. I bought some wire. Took the diagram and did one wire at a time. Just laid them out one by one. Made checks along the way per Bob M's note. I could get it to discharge
but not charge. "GROUND" I had the face panel and switch hanging out of the box and soon as I grounded it; I started the engine and it showed about a 10 amp charging.

Now I am in the process of rewiring the tractor, The old wiring was very brittle and insulation was bad. Gentlemen -- Thanks for the help.

Ray Heck
Now just waiting for a plow day.

Need Help From Bob M or others

Ray Heck

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Janicholson

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Ray Heck

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