[AT] Oh No! Did I buy the wrong wiring harness?

[Ben Wagner]

Thanks, Mr. Vinson.  I'll try to adapt my wiring harness and see if I can make do.  My old generator was made for a voltage regulator, so my tractor was modified like your "M".

Ben Wagner

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Date: Mon, 5 Apr 2010 20:27:21 -0400
From: "Dean Vinson" <dean at vinsonfarm.net>
Subject: Re: [AT] Oh No!  Did I buy the wrong wiring harness?
To: "'Antique tractor email discussion group'"
	<at at lists.antique-tractor.com>
Message-ID: <000f01cad51f$ed132dc0$c7398940$@net>
Content-Type: text/plain;	charset="us-ascii"

Hi Ben.  The "relay" is also known as a "cutout relay," and its purpose is
to allow the generator to charge the battery but prevent current from
flowing back the other way and draining the battery.  On a tractor with a
cutout relay (rather than a voltage regulator) the operator manually
controls the charging rate via the light switch knob on the electrical
control panel.  In addition to "D" and "B" positions (for dim and bright
lights), the knob has "H" and "L" positions for high and low charge.
Either of the lights-on positions also resulted in high charge.

Somewhere along the line voltage regulators started being used, and just
like the cutout relay they allow current to flow from the generator into the
battery but prevent it from flowing the other way.  But they also
automatically control the battery charging, shutting it off when the battery
is fully charged.

It's pretty common for voltage regulators to have been added to tractors
that originally came with cutout relays, which may be what has happened with
your tractor.  (Same thing happened to my 1950 M.  See
http://www.vinsonfarm.net/suburban_M.html for some of the details, which is
how I happened to learn a little about cutout relays).

I'm sure you can adapt the wiring harness--it just takes figuring out which
wire needs to go where, given that you have a regulator rather than a relay.
Check out Bob Melville's wiring diagrams at
http://s101.photobucket.com/albums/m46/farmallbob/Farmall%20Tractor%20Wiring
%20Diagrams/ for help.  Pay attention to your light switch, also--you can
still use it even if it has the H and L positions by just ignoring those
particular terminals.

Have fun!

Dean Vinson
Dayton, Ohio
www.vinsonfarm.net