Holy Mackeral! I missed the notification that this thread was rockin' until this morning.
And I'm really REALLY sorry that y'all had to work so hard on that "strobe" part of the puzzler as a result. Here's more/better info.
The root cause problem that started all this trouble was that I was mowing dense brush and a stick jammed the cooling fan. I'm not sure why the fuse didn't blow, but it didn't. The fan is (probably) burned up as a result. The thing that caused me to notice was sudden heavy load on the tractor (pulling down RPMs) and super-drain on the battery. I was on a really steep slope so I backed up to level ground and just as I got there the tractor quit. Once I was off the machine I saw the stick in the fan. Pulled it out and the fan doesn't turn (and has that lovely burned-motor smell).
I pulled a lead off the fan, and I also pulled off one side of the thermostat in an effort to get the tractor home to the barn. [update] I think I have to go back and take a look at the strobe to confirm what it's doing when the tractor is running with the breaker open.
The first time I ran it that way, the tractor got about 50 feet and quit when the breaker popped again (probably fuel solenoid dropped open on low voltage -- it trips around 11 volts and the battery was low because it had just been drained by the jammed fan). I replaced the three year old battery and that's how I got back to the barn. The voltage momentarily dropped, but I bet not low enough to shut off the solenoid, and then kicked up to a charging voltage. Off I went, made it to the barn.
As I drove to the barn, the voltage slowly dropped from 13.2-ish down to closer to 13-ish.
Again, apologies all round on that -- I'll keep a closer eye on the thread today.
Pulled out and tested the ignition switch yesterday -- short version, seems to be OK. Off: red is isolated from all other wires. Start: red is common to all wires. Run: red is common to green and yellow. Acc: red is common to yellow. I forgot to run Soundguy's "pull off yellow and see what happens" test until I'd reassembled the ignition switch and the dash.
The Deutz guy says the alternator has an internal voltage regulator so I'm thinking that it's just connected directly to the battery and isn't switched -- which would explain why it doesn't show up on any of the wiring diagrams. Make sense?
What do people think of the theory that the alternator's goofed up? I have a brand new $20 short-finder and a brand new $600 alternator. So I'm thinking today's project starts with the short-finder.
