I have Cub Cadet XT1 that started blowing the fuse last month, only when running. I traced it down to the voltage regulator, if I disconnect it the short goes away mower runs but doesn't charge. I tested the stator, it puts out 20 - 34 volts AC, no short to ground and the milliohms test is within range. I purchased a new voltage regulator and installed it, same issue. I tested further today and found that with the voltage regulator connected but not mounted to the engine ( I had it wrapped in a welding glove ), I can see the same AC voltage, I can see the battery voltage on the middle terminal ( 12.5 vdc to engine case ), but between the body of the regulator and ground, I read 12.3 vdc to ground. I shouldn't see voltage on the body of the regulator, are both of these regulators bad? Keep in mind this only happens when running. With the engine off, key on or off and the regulator mounted and plugged in, the fuse does not blow, but as soon as it starts, it will pop the fuse. I set my meter up to measure amperage and put it in place of the fuse and you can see it run up to 10+ amps once it starts ( I pulled my meter out as the internal fuse is only good for 10A).
For now is sits on a charger the night before I need to mow, but I'd like to resolve this.
First I would check all the wires, looking for a cracked or scored wire shorting to ground, which is the most common cause of blown fuses. Make sure you remove the shroud, as critters love to build nests and chew on wires there. Finding all wires good use this manual to test all parts of the charging and starting systems. https://www.mymowerparts.com/pdf/Ko...urage-SV470-SV480-SV530-SV540-SV590-SV600.pdf
Also check the main ground connection. a loose or corroded one can cause fuses to blow but not show as a problem with a meter.
And yes the case on just about all rectifiers is both a heat sink and grounded .
Thank you for the link to the Kohler manual. I have already preformed these tests and they all passed.
I will try the first test tomorrow with the B+ lead removed from the regulator.
The fuse only blows when the regulator is mounted and engine is running. If I remove the regulator it all runs with no issue, just no charging. If I mount and connect the regulator, but don't start the engine, the fuse if fine.
The case of the regulator is supposed to be a ground, but when the engine is running, I can measure 25.3 vdc from the regulator case to the engine case (with the regulator not mounted on the engine).
