You really need to use a voltage meter to check a diode. I am not familiar with your test light and how much voltage will make it light up. If you got conflicting results checking with HF meter with diode test I was giving you the info to test with a battery and voltmeter and what the voltages across the diode should be forward and reverse biased. Wiring diagram is to small for my old eyes to read and suggest what the diode function is.

My other response to Billy O was an explanation of why you see diodes spliced into tractor wiring.

After the 1985 flood,, we went looking for a generator,,

https://en.wikipedia.org/wiki/1985_Election_Day_floods

There were none to be found, but,,, walking through Sams Club, I noticed they had an engine powered welder on the shelf,,

I looked at the paperwork, it mentioned the wheel kit,, but, that could not be found,
an associate gave me a $100 discount because the wheels were "missing",, :bigthink:

We paid for it (~$300) took it home, filled the 10HP Kohler with oil, and fired it up,,

It was a perfect generator, and a perfect "buzz box" AC welder,,

It ran 100's of hours as a generator, and probably 100's of hours as a welder,,

One day a guy who owned a dozer was at my house saw it,, and had to have it.
He gave me $500 and the excavating project I wanted,, :biggrin2:

So, my Lincoln welder was gone, but, I got a new Miller Bobcat engine welder.

Mine was not electric start, but, one pull of the rope,, it was running,,

I did adapt a small automotive muffler to it,, the original muffler was LOUD!!

ejl6658 I really appreciate that.:beerchug:

I have tried to add some more detail to part of the diagram....

Under the symbol for flashing diode, it looks like it says 3A.

The two circles on the lower left portion of the diagram are the brass rings with the brushes and under that it says ROTOR FIELD.

Next to that it says ??? ??? CAPACITOR

That's a great deal there CADplans. This thing is very loud too. I wont even start it without ear muffs on.

I went to NAPA, asked for the smallest oval shaped muffler, bought 2 clamps, and a reducer,, and slid the muffler on the exhaust pipe
(the original muffler was removed)
The oval muffler pointed up,, the Lincoln sounded like an electric motor with that muffler on.

I slid the muffler off when it was not being used, I never clamped it on tight,,

That was the smoothest running gasoline engine I have ever owned, cars and trucks included,,,

Tell me if this makes sense;

"The magneto flashing coil picks up dc voltage from the Kohler engine magneto. This dc voltage 'flashes' the exciter field in the alternator to restore residual magnetism for the purpose of initiating power output. "

:bigthink:

Yes, makes good sense.
Some Generators will not make power after sitting a while.
I have a coleman gen set I got new maybe 15-20 years ago and in the service manual with it, it describes how to "reflash" using a small lantern battery to excite it if it no longer produces power.
I've never had to do it.

But I had a girlfriend in my youth that would "flash" me, and boy oh boy did it "excite" me
She said it made me a real "power house":biggrin2: so I guess it works for a Generator also:beerchug:

:bigeyes::bigeyes: Every young mans dream.