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Connecting a Hitachi #14231 12volt to a Farmall H

Y

Yooper Farmall

Member
I've bolted up a new Hitachi 12 volt alternator to a 1941 H using an aftermarket alternator bracet that I already had. I have a wiring question:

currently, applying 12 volts to the "S" terminal does not excite the field and cause the alternator to start chargine. However applying 12 volts to teh "L" terminal does. The problem is that if the voltage is applied to "L" at all times, there is a constant draw. If a switch is introduced in the circuit to the "L" termnial, it back feeds the coil and the tractor will not shut off. What is the fix to this? I see Dean has wired up a diod of some sort on his 300 Farmall. I'd prefer not to have to add a charging toggle switch on the light bar.
 
The diode will work and is what most use, I have used a small relay from radio shack energized by the ignition switch and have also used a oil pressure switch that is normally open to disconnect the alternator when the oil pressure gets down to 4 or 5 psi. This switch is also used to turn off the hour meter if the trractor is not running and the switch is left on. The diode is by far the easiest to install.
 
The diode is workable, the use of a resistor (10 to 20 ohm at 10 watts) or a parking light bulb (not LED type) wioll also work.
The diode should be placed with the banded end toward the alternator.
The S terminal should be connected to the Bat (large output) terminal with a short #12 wire.
I recommend putting a 40 amp fuse link in the wire going from the alternator to the amp meter. This prevents electrical fires if things go wrong, or a battery is hooked up backwards. Jim
 
Check the archives. I have posted the wiring several times. I am away from home or I would post it again.

PS: We need a better way to search the archives.
 
Diode is a part #276-1143 purchased at Radio Shack for $1.69 for 2. White strip on diode goes towards the alternator.
S goes to stud on alternator, right next to plug.
L goes to ignition through diode. I ran mine to the + terminal on coil.

Works great. This was my second conversion. My SH is about a year old with no failure.
I am not the originator of this info. Thanks to all who helped me figure it out.
 
The wiring is basically the same for the Hitachi as the Delco. As I recall, there are two terminals you need to connect together, maybe S and L?

I used a panel mount LED that I bought from AutoZone, which I placed in the hole where the fuse would normally go.

The LED is wired from the ignition switch, to the alternator. Once the alternator is excited, the LED goes out.

Unfortunately, I can't find the panel mount LED at any auto parts store anymore.
 
The S is Sensor, it is = to the #2 terminal on the Delco. The L is light (idiot light) and that is = to the #1 terminal on the Delco. Jim
 
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