Tractor died, won't start.

Check the battery terminal at the regulator with a test light. I'm betting you find no voltage.

You may have a resistance somewhere else in the wiring and by shorting the resistor you compensated for that resistance. I would still check ALL wiring between the battery and the ignition switch and the resistor. Go ahead and put a new resistance in, but be prepared to check the wiring if the resistor doesn't fix the problem.

You quite likely burnt a wire somewhere between the regulator and the battery. One thing I see here that everybody missed is Ford generators are backwards from everything else. Our A-C's with a Delco generator control the field on the GROUND side of the circuit. That's why when you ground the F terminal on a Delco, it gives maximum charge. Ford on the other hand chose to control the SUPPLY side. So when you grounded the Field to the chassis, you created a direct short to ground and something couldn't take it. My guess is the ignition switch or a splice in the harness. You've probably welded the points in the regulator too.

oops I was slow on the typing.  Good deal.

Just use a jumper and bypass the resistor and see if it will start.  Don't keep it that way as it may overheat the coil but for a test it's quick and will tell you if the resistor is bad or not.

It sounds WAY simpler to me, if you have voltage at the resistor and NOT after the  resistor, just replace the resistor. 

I presume that it cranks but does not start, yes?

Thanks for that explanation.

So you don't think the resistor is the problem?

Ok, maybe not a ballast resistor, but it's a ceramic resistor like this

turn key on and see if there's 3 -6 volts on the coil side of the 'ballast resistor'. You should get 6 if the points are open, 3 if closed.
if you get ZERO volts, ballast resistor is kaput ( open).

If you have a wire with mostly broken strands the extra current could have overheated and melted the few remaining strands. Just one possibility.

Don't be surprised if the problem is where the wire crimps into the terminal. Those faults can be a bear to find.

Thanks guys.

There are two possible connections for a generator field coil. One connects one end of the coil to the armature, then the regulator or light switch grounds the other end for maximum charging. The other connection grounds one end of the field coil and connects the other end with the regulator or light switch to the armature. In the second connection grounding the F terminal SHORTs the generator output and with the cutout engaged the battery. That will draw lots of current and fry any bad connections or fuses or small wires in the circuit.

To detect voltage in circuits one can use a voltmeter or a test lamp. Where there is a possibility of a poor connection, I prefer a 1 amp test lamp to a volt meter that might draw as little as 50 microamps, 20,000 times less current than the test lamp. I have to make my test lamp using a handy 6 or 12 volt lamp with a wires added. A 50 watt 12 volt lamp from the RV section at wallyworld is a handy test lamp for 12 volts too. For 6 volts you need a 6 volt lamp.

I also prefer a lamp in series with the circuit under test when looking for a short, because it indicates a short without burning out like a fuse and it limits the current to a short to keep wires from being overheated.

Gerald J.