What a fun day I had. Fairly cool out this AM So I thought I'll get the lawn mowed. So about ½ way through I stopped to grab a small branch that had fallen. I forgot to shut the PTO on the tractor off so it shut the engine off when I raised up off the seat, Gotta love the safety features 😉. So, I jump back on hit the key and nothing, nada, ZERO. Hmm, must've blown a fuse. I proceed to locate the hidden locations (can't put them where they're visible or accessible). All appear good.

So get the other tractor and tow if up to the shop as its acting a bit strange with the warning lights sometimes coming and sometimes not. Get out the schematic and begin 5+ hours of chasing my tail. Battery Voltage is OK at 12.5. I proceed to chase the V to various relays and switches. After it sits for a couple of minutes everything is normal until one hits the glow plug warm up (diesel) or tries to start it. THERE WAS A BIG CLUE THERE
I suspect something is causing a draw and there is a delay timer in the power circuit that I'm still not quite sure what it's purpose is, but suspect it may be faulty due to the way the dash lights etc. are acting. It bench tests fine. However the voltages at the connector are acting a bit strange. SEE ABOVE 😉. I begin disconnecting / bypassing thing looking for the DRAW. Eventually I get all the way to the starter. AH HA, if I disconnect the solenoid, all seems well. I try a remote switch on just the starter and NADA. Shorted solenoid? I scratch my a-s a bit more and start hooking some of the items back up and removing the bypasses. Things are good until I hook the glow plugs back up. Almost back to square on but not quite? Scratch a-s some more, smell fingers for good luck . Test all 3 glow plugs. They test fine. WT-O??? At this point I have tested about everything I can think of including multiple V tests. I leave the DVM hooked up and proceed to discover that as soon as one puts a significant load on the system the Voltage drops rapidly to about 2.5V. once the load is removed it climbs back up to 12.5 in about a minute. Bad Battery?[b] Yes sir[/b]. In over 50+ years I have have had a few just magically die, but never had one that would recover V wise as this one did and act this way.
Almost forgot to mention that at one point I was going to finish mowing with the big tractor at which time I discovered it's new alternator put on during the winter was no longer functioning.
GREAT DAY 😊 Hoping yours was better

EEeeyyyyeah, that sounds lovely.
But for a second there, I thought there was going to be an injury report.
As per my racer/fabricator buddy's motto, Nothing Is Ever Easy

Over MANY years and repetition to beat it through the thick skull,

1. ALWAYS start with a fresh battery to avoid chasing tails.
2. When electrical problems begin, start by checking EVERY fuse, again, to avoid chasing tails.

It's funny when you have, for instance courtesy lights that won't turn off, it's a blown fuse in a seemingly unrelated circuit. 1969 Grand Prix. I don't remember which fuse it was anymore.

On a 67 GTO, it was a brake light fuse being blown that caused that situation. Had that happen to a customer back when I was wrenching.

Last year my wife's mower would start when cold but if you turned it of it would spin and spin and never start. Leave it for a couple of hours and it would fire up again.

I checked everything I knew to check. One day we ground the battery down to dead trying to start it, and she decided to get a new battery. I'm thinking there's money wasted because this thing is going to be junked and replaced, but the new battery fixed it.

I do not understand, but do not care. I'm just glad we didn't end up having to buy a new mower.

Yes, I said it's my wife's mower. She's the best.

had something very similar happen to my MIL's car. Lights, radio and such would work. Try to start is and nothing, not even clickity click.

Came over, put my meter on the battery, read 12.8ish. had her turn on the head lights and zoom, below 10v. One new battery later we were good to go. Seen this one before in my clunker years, so I always do an impromptu load test like that when I see similar symptoms, bet you will too now.

Something about mowers. I'm working on a Toro zero turn that won't start. Found a wiring diagram and went through the start circuit. Ignition switch was hosed up so ordered a new switch. No go. Soooo, started going through the rest of the start circuit, the PTO switch was shot as were both park interlock switches. I'm thinking, this can't be, multiple failures? But yes Virginia, all of the components were defective. Then I talk to the owner and he tells me it had blown a fuse just before it wouldn't start.....uh oh......I'm thinking the problem is still there. The new switches are supposed to arrive today, we'll see.

That is exactly the test I normally do But I was thrown two curve balls, 1. It had started an hour earlier just fine. 2. the headlights wouldn't turn on and I'll be honest and say I didn't know that they would without the motor running, but ASSumed not.

Then the dash lights were flaking. Fuses all LOOKED good but I've been burnt on that one before. Once in the shop, all the voltages looked good but flakey at times. By that time, looking at the schematic the time delay relay had gotten my attention as most everything goes through it power wise. I was not even thinking battery (can you say "tunnel vision") ? I've always said
"Lessons paid for are best remembered" I guarantee you I'll remember this one LOL

And I'll check that headlight operation today when I finish mowing and report back. I'm glad some are enjoying and hopefully learning from the post

i'm super glad the neighbor kid cuts my grass.

I’m glad it’s just the tractor and not you!
With my recent health scare I thought you were going to say it was something that happened to you!?!?
Thank goodness you’re ok, tractor can be fixed. Take your time and don’t get worked up over it! 👍🏻👍🏻

Thank you and yes all is well I had my health attitude adjusted 5 years ago> They went in to do a stent or two. OPPS not so easy this time Wound up getting a triple bypass that went sideways. I was in an induced coma for 4 weeks, 1 week in an advanced care facility, then 3 weeks of rehab. Another 12+ months for my brain to unscramble due to the 4 weeks of Propofol and Fentanyl. haven't smoked or drank ANY alcohol since

Good man!👍🏻👍🏻