Farmall M electrical question

paramedicchuck · Oct 1, 2011

Please help. I am not the greatest with the 6 volt electrical. I am re-doing a few minor things on my 49 M. I replaced the wiring for the lights. I used regular old 16 ga wire, hooked to each light. I joined the wires together and terminated them with a ring connector and hooked it up to the screw in the electrical box with the switch.

When I tested the lights before putting everything back together, they worked fine. I put the box back together, and now i have nothing. No charge or discharge on the ammeter, no lights, no nothing. I am able to start it and run the tractor without any problems, but the lights don't work and I don't get a positive or negative reading on the ammeter.

What did I do?

Janicholson · Oct 1, 2011

16 gauge is really too small for 6v systems. It
will work, but it will not carry the voltage well
12 gauge is more realistic, the reason being that
the lights need all the electrons available to
work even modestly. The light system is fused on
the back of the switch. A 20 amp fuse is clipped
in the holder. The wiring may have come in
contact with metal at some point. Trace the wires
with a test light. (I would change it to 12 ga,
with soldered connections and shrink tubing on
each connection. Jim

paramedicchuck · Oct 1, 2011

Thanks Jim. So if the wiring came in contact with something, what's the remedy? I think it did....

Janicholson · Oct 1, 2011

New fuse. that is all. Jim

paramedicchuck · Oct 1, 2011

OK. The fuse looked OK, but I will replace it and see what happens. Thanks again.

Janicholson · Oct 2, 2011

Use a test light. they are ~2.50$ They look like
a small screw driver and have a wire attached.
The power should be found at the wire supplying
the fuse, both ends of the fuse, the bracket of
the fuse holder to the switch, the wire connecting
to the lights, and at each light.
Poor connections at any point will thus be
evident.
The dimming resistor on the IH light switch must
be good to have Dim lights. If it is not good,
there will be no voltage for the test light on D
position.
If the tractor is equipped with light bulbs or
sealed beams from other applications that draw
more watts than the original, the D position will
burn out the wire resistor in a flash. the switch
is not good for much more than the original
lights, unless run through a power relay to avoid
over loading the switch contacts. Keep us in the
loop. Jim

paramedicchuck · Oct 10, 2011

I was able to rewire the lights with 12 ga wire, replace the fuse, and check the electrical system with a test light. Everything is working, except....

I don't get a positive charge on the ammeter. When the lights are on, regardless if the tractor is running or not, I get a negative reading. When the lights are on high beam, the discharge rate is increased, so it seems the gauge is working.

Any thoughts on this issue? I am going to research polarizing the generator....if that doesn't work, anyone have any words of wisdom?

Thank you!

Chuck

paramedicchuck · Oct 10, 2011

Polarizing the generator didn't help.

So to review, I didn't disconnect the battery when I rewired the first time. I know I saw a spark when I was hooking up the wires the first time...I must have touched it to something it wasn't supposed to touch. I have since replaced the fuse and rewired the lights with 12 ga wire, per the recommendation above.

The lights work now, but I do not appear to be getting a charge on the ammeter. It reads discharge when the lights are on low or high beam. I have been searching the forum for troubleshooting ideas, but haven't found anything yet. Again, I am an amateur with the electrical stuff.

Thanks again....

Chuck

Farmall M electrical question

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