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Ronald, Bob usually posts his nice picture to answer your question while Bob M has a great wiring diagram n Old n myself n others describe it for you IFFFFF F youre planning to use the GM 10 SI 3 wire alternator wired to work like a one wire, and they, like most alternators, REQUIRE NEGATIVE GROUND. The One Wires can require a higher RPM to excite while some (depends on internal regulator used) cause a very small trickle discharge, so due the the low cost and easy availability I prefer the GM 10 SI wired as described below. NOTE mine and Bob n Bob M's n Old's methods are slightly different and both work fine, I just prefer to use the current limiting 10 ohm resistor (might protect the diodes) versus a diode and in most cases the diode isnt even required when it or an idiot light is used in the excitation circuit. The tractor MUST be used at Negative ground and heres how I describe wiring them. Bob M’s great diagrams puts it in pictures, which they say is worth a thousand words, so take a look and see for yourself. Heres how I wire a GM 10SI Alternator and remember, it requires NEGATIVE GROUND !!!!! ! The big rear main alternator output terminal goes to the wire that used to be connected to the BAT terminal on the Voltage Regulator or Cutout Relay. HOWEVER if that wire wasnt already upgraded, when I convert from a Genny to an Alternator, I replace that wire with a 10 Gauge and it runs from the alternators main output up to the LOAD (NOT to battery/starter) side of the ammeter. I also replace/use 10 Gauge from the ammeters other SUPPLY terminal to the battery/starter. The little side number 2F Voltage Sense Terminal gets connected (use a short 14 jumper wire) right up to to and with the big main output terminal mentioned above. For the little 1R side Excitation Terminal, run a 16 or so gauge wire from the ignition switches IGN (which is HOT ONLY when ignition is turned on) terminal and in series with it place a 10 ohm 5 watt current limiting protection resistor (dont really need that much wattage power rating, but they are heavy duty built and easy to wire). Then in the rare event the tractor continues to run cuz of alternator backfeed when the ignition is switched OFF, I add in series a 5 amp 50 PIV minimum Diode. The diode must be wired with negative cathode end to the alternator and positive anode end to the switch. Again, the ratings are not that exact but about any diode over a few amps and 50 volts or so works. Dont forget to change the battery to negative ground and the coil needs to be wired so the negative goes to ground via the distributor points and the positive gets power from the ignition switch and you have to reverse ammeter leads also if your just now changing polarities. Good luck Ol John T in Indiana
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