Voltage Regulator Rectifier for Kohler 41 403 10-S 41 403 09-S 25 403 03-S

I used this product to swap out the regulator on a John Deere LT160 lawn tractor. Upon removing the old unit, I found the inscription read 41 403 09. This part works works perfectly as a replacement. I measured 14.26 DC volts at the battery after installation (12.4V with the old unit in place) and now the battery charges like new. You can test if the regulator is the problem by measuring the AC voltage across the outer two electrodes while the mower is running: if it registers around 22 VAC your alternator is fine. You then check the DC voltage between the middle electrode (+) and ground (-). It should be around 14.25 VDC. In my case the latter test failed and this unit fixed the problem.

Great part, after fixing the main problem! Installed on Kohler command 23hp vtwin on my scotts/john deer tractor. After installing I was hopeful, still no charging output. Checked stator wires for shorts/opens, none found. Switched to AC volts on meter running full throttle, 30-45ac volts should be present on 2 outside wires that connect to regulator, still no output. After removing flywheel found all 6 magnets came unglued and stuck to stator. Turns out this is common problem with Kohler command engines. Quick youtube search later found correct procedure to jb weld magnets back to flywheel IF they are not broken. If they are, sol & new flywheel is $280-300 Once back together found 14.4 volts at full throttle and pto/lights on.

Good part works as advertised.

The regulator has a design flaw that you may need to look for. If your mower has a metal shroud like my Kohler engine has the terminals will short out against the metal. Luckily I caught this while hooking the battery back up I noticed therewas some sparking at the battery terminals. The original regulator has shorter terminals and a plastic spacer on the back keeping it away from the shroud. If your engine has a plastic shroud this wouldn't be a problem. So far this is working fineso I'm hoping I dodged a bullet and didn't do any damage to it.

Fit my Kohler Courage 22 hp eng in 2006 Toro LX500. Fixed the charging problems and is on it's second season. There are good videos on YouTube to see how to use a multi meter to test your old one. A simple way to get a fairly good idea on how your charging system is operating is to take a voltage reading at the battery posts with the engine running. If it's not charging you'll see battery voltage, 12.8 or so and it will slowly drop. It should be approx 14 volts if the charging system is operating properly.

The old voltage regulator fried when the wiring harness chaffed, shorted out and melted. I was using a battery charger to keep the battery up between mowings but that got old quick. This and a couple of new wires and the old mower charges again! Considering the OEM Kohler part is around $60 you can't beat the price and it works just as good.

Worked perfect for my Koehler command engine on my John deer l130 riding mower. Exact fit all around with bolt pattern on the blower housing as well as the wiring harness terminal end. Both outer poles for the stator a/c voltage going into regulator and the middle pole for battery voltage are exact oem specs.

Honestly, I threw this part at my non-charging mower without all the testing of the stator etc. It seemed the most likely item to fail and it was the easiest to replace. I did bench test the old regulator and it was "open" in both directions which indicates one or more failed diodes. Just use a multimeter set on Ohms and check for continuity between the center and each outer pole, between the outer poles, and between all poles and ground. Mine showed zero connection or infinite resistance between all poles which means it was shot. Mower starts and charges now like a champ!