Ignition/starter switch issues

[Alpha Dog]

I changed the fuel filter on the wife's Kubota L275 2wd earlier this week, and while cranking it to clear the bubbles out of the lines, it suddenly went dark and dead. Battery didn't slow down, or dim, everything just quit. Had a similar issue last year, replaced two front wiring harnesses for $250+ before learning the starter/ignition whatever it's called switch had a short in it. Replaced switch, problem solved. Now it's doing the same thing, not even any dashboard warning lights, but battery is good, and fusible link looks good and tested with Ohm-meter, shows continuity. I'm guessing the switch is kaput again, but can't figure out why. I mean, it's just a key operated rotary switch, right? I've been turning wrenches on cars, trucks, tractors, lawn-mowers, go-karts, whatever, since about 1969, and in that time, I've only seen two other ignition switches short out, and now there appear to be two in less than a year? Is this a known Kubota issue, or is there an underlying problem anyone can think of that might cause the switches to short out?

 

[Alpha Dog]

Just for passing information, I hooked the leads on my "load tester" (a cheap one, and I should have known better) to each other, and pushed the button. It showed there was a "good" battery, even though there was no battery there at all. I would have thought a bad load tester would have showed a good battery as failing, not a bad battery as passing. However, apparently it was a bad battery after all. (After spending three hours trying to figure this out, taking the dashboard off, and tracing just about every wire in the tractor from one end to the other before realizing I had a bad battery tester, I also tested the el-cheap-o tester to see if it would fly. Unfortunately, it failed the anti-gravity test.)

 

[rbargeron]

On my L345's there is an exposed fuse (fusible link) on the firewall that gets corroded big time. It may test fine with an ohmeter but it can't conduct enough current to do anything useful. A voltmeter may show full battery voltage too. But dc voltage is just like dc resistance - a static condition, not a predictor of how much electron traffic the system can handle. Once replaced with a new 30-amp in-line fuse, all was good again.

 

[Alpha Dog]

Thanks, been through the "fusible link" thing before, when I replaced the switch, the link was replaced, but didn't fix it. What I found that time was the bad switch, this time, it turns out that it was that both the battery and my "Load tester" (not the ohm-meter) that were B-A-D. New battery and it fired right up. New load tester has been ordered though an online tool house. (With three tractors, three pickups, an SUV, and two motorcycles in my "electric start" group, I end up testing batteries fairly often. In fact, I think I use so many lead-acid batteries that I'm doing my part to keep the economy moving by keeping at least one lead mine going full time!)