Kohler sv600s on a husqvarna yth2040 blows fuse

[mr.farmall]

this mower will blow a fuse each time the pto is engaged.
I started testing the pto switch and it test just as described in the wiring schematic. I disconnected the pto connector and ohme'd it at 3.2 ohms. then tested it with an external battery. It engages and disengages normally and draw about 5 amps. I also tested the pto switch, it test good as described in the schematic.
with the connector back in place for both the pto and the pto switch, it now blows a fuse every time the mower is turned to the on position from the off position without starting it. I disconnected the pto and tried it again and it blows a fuse with the pto connection off.
I disconnected the rectifier and tested the stator using the kohler sv600s testing instructions. It has 0.2 ohms, just as indicted from kohler. I did an ohm test from the "B" lead of the rectifier to the two stator connections of the rectifier. one is completely open and the other completely shorted. I don't have a regulator tester so I could go no further. I started the engine with the rectifier connection off. it starts just fine, it doesn't blow a fuse. With a meter across the stator leads, and the engine running, I get 44 volts.
still with the engine running I connected the pto and tried the pto again. it didn't operate. I stopped the engine and checked the pto switch again. this time it fail for the Normally open connection going to the pto. i connected a jumper across the now bad connection of the pto switch, started the engine and the pto engages and disengages just fine and doesn't blow a fuse, but the regulator is still disconnected.
I have added the schematic I've been using.
if anyone has experience of knowledge that might help, I would appreciate it!
and one last thing, The battery had previously been installed backwardbefor all the trouble began. Negative lead on the positive terminal and vice-versa. View attachment 26003

 

[ILENGINE]

I just went through the same thing on a CV730 a couple of weeks ago. Regulator test good with the Kohler regulator tester. One lead of the stator works fine, the other lead shorted to ground. In this case it actually melted the wires attached to the regulator. So I removed the flywheel to replace the stator and found the flywheel magnets were no longer attached to the flywheel. All six magnets were stuck to the stator.

From my research found that they are using a half wave rectifier system, not a full wave bridge rectifier.

Sounds like you have a faulty stator allowing the battery to short through the regulator to ground

 

[mr.farmall]

I just went through the same thing on a CV730 a couple of weeks ago. Regulator test good with the Kohler regulator tester. One lead of the stator works fine, the other lead shorted to ground.

From my research found that they are using a half wave rectifier system, not a full wave bridge rectifier.

Sounds like you have a faulty stator allowing the battery to short through the regulator to ground

I don't have a way of checking the regulator other than the ohms test I stated earlier. my test was made from the B terminal to each of the stator terminals, not to the stator itself, just through the regulator.
I have now tested the stator leads to ground. both look good, both are completely isolated from ground, and across them it reads about0.2 ohms. This is in specs per the kohler manual. After all, its just a piece of continuous wire rapped around a lot of iron cores that make up the stator. if any part gets a short to ground, it should show up at both stater leads when measured to ground.
I have 2 concerns;
1. how to further test the rectifier since it blows the fuse immediately upon turning on the ignition switch with the rectifier connected,
2. with the engine running, 44 volts ac across the stator leads seems a high, I would think it should be lower, but then again, it isn't producing anything when the engine isn't running. that is when the fuse blows, as you turn the ignition on with the rectifier connected before it has a chance to switch past the on setting to the start setting. instantaneously!
I opened the pto switch up to check it since it had stopped working and found that the internal copper connection on the center switch( it has three) had lost all of it's strength. you could effortlessly bend them while the other two were stiff as they should be. It probably got very hot and annealed the copper to make it that pliable
one last question, what is the shorting connection? it is found on the diagram just under the revers switch and the seat switches. And were is it located?

 

[ILENGINE]

From your description of the problem it sounds like the rectifier is shorted. You can take it to any Kohler dealer and have them test the regulator/rectifier. The Kohler regulator tester is a required tool for all Kohler dealers.

The shorting switch is internal to the connector that connects to the safety switch. For example unplug the seat switch and look inside of the connector. The center part between the prong slots, should have a piece that will depress with light pressure from a screwdriver. When you unplug the connector from the switch that piece is spring loaded and comes up, which in turn releases the spring wire that shorts across the prongs inside the connector. It is a way to prevent people from just unplugging the switch.

I should of explained my stator situation a little better. In my case when the magnets came loose it broke the stator winding. So I didn't have continuity from prong to prong. So one prong was shorted to ground, and the other wasn't. But since the magnets didn't turn I didn't have power output.

My regulator tester showed my regulator to be good. But I have continuity from the B terminal to one of the prongs going to the stator. The other terminal showed a high resistance, which would be normal when going through a diode. The B to terminal with continuity seemed strange to me, but may be normal considering it is a half wave rectifier.

 

[mr.farmall]

From your description of the problem it sounds like the rectifier is shorted. You can take it to any Kohler dealer and have them test the regulator/rectifier. The Kohler regulator tester is a required tool for all Kohler dealers.

We have a dealer near by. I'll have to see if they will test it for me. thanks for the tip.

The shorting switch is internal to the connector that connects to the safety switch. For example unplug the seat switch and look inside of the connector. The center part between the prong slots, should have a piece that will depress with light pressure from a screwdriver. When you unplug the connector from the switch that piece is spring loaded and comes up, which in turn releases the spring wire that shorts across the prongs inside the connector. It is a way to prevent people from just unplugging the switch.

This little switch really had me going, I could not find it anywhere! now with your explanation, it makes a lot of sense. Thanks so much.

My regulator tester showed my regulator to be good. But I have continuity from the B terminal to one of the prongs going to the stator. The other terminal showed a high resistance, which would be normal when going through a diode. The B to terminal with continuity seemed strange to me, but may be normal considering it is a half wave rectifier.

we had half wave rectifying diodes on our dirt bikes when I was a kid. They barely kept the batteries charged and everything else on the bike was powered directly from the stator.
This mower has put out 15 amp as indicated on the amp meter. It must have something a little better than a half wave rectifier. The parts store wants about $70 for the rectifier. I hope it has a little more to it than just a rectifying diode!
thanks again for your help. "Experience has no substitute". you have proven that again on this post.

Once again I would like to point out that the battery was installed with the positive and negative leads reversed for at least one week. It had tried to start more than once, but of coarse couldn't. I'm leaning toward this as the reason for the fuse blowing all the time now. Their are indications that the stator wires have gotten very hot and the pto switch also failed. haven't check the rectifier yet but I could see it having failed also from the reverse wired battery.
wish me good in tracking down this problem.
Thanks for your help
Rex

 

[ILENGINE]

On the kohler dealer site, it shows the 41 403 10-s as a regulator/rectifier with a kohler note of half wave 15 amp. it shows this part number being used on 1,100 engines by specification.

 

[mr.farmall]

On the kohler dealer site, it shows the 41 403 10-s as a regulator/rectifier with a kohler note of half wave 15 amp. it shows this part number being used on 1,100 engines by specification.

Upon looking up the numbers, It does state that it is half wave rectification. I suspect that is also includes a voltage regulator in its make up. It did say regulator/rectifier. I hope that means both regulation and rectification.
We'll get it tested and go from there.
Thanks again for your help.
Have a great week.
Rex

 

[mwrman]

Also have you checked all the wiring? Something that maybe burned or rubbed through

 

[mr.farmall]

Also have you checked all the wiring? Something that maybe burned or rubbed through

As far as I can see, all the rest of the wiring looks good, nothing showing a problem as it passes corners and through holes. using a VOM where possible, every thing tested seems to be as the wiring schematic indicates. Although, it still blows a fuse with the rectifier plugged in and doesn't blow the fuse with the leads pulled off of the rectifier. I think this is a good indication that the problem lies with the rectifier and / or stator. 44v out of the stator concerns me but it's windings seem to be in specs with the ohm meter. no other shorts or grounds on the stator.
Were getting close to the problem.
I have a new PTO switch on order and a new rectifier coming. I'll let you know the results when they get here. Thanks again for all your help.
Rex

 

[mr.farmall]

Also have you checked all the wiring? Something that maybe burned or rubbed through

got the new parts installed today. No more blown fuses! the regulator is putting out about 14 v. and does not have the short to ground on one of the ac leads as the old one did.
Thanks for your help.