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I have a Scag Turf Tiger with a 26 Kohler EFI engine. The engine is relatively new however, I have changed the stator regulator and key switch.
The battery isn’t charging.
All fuses check out ok and the gauge on the console shows on the low side not charging while running.
The battery shows battery voltage at WOT.
The regulator shows 38 VAC from the stator. The DC wire shows no voltage. When moving the test lead to battery negative there’s no reading. However when moving the positive lead to battery positive I get battery voltage.
The positive circuit is open.
All wires look good, no burns corrosion or anything abnormal.
Any ideas what to look for next?


Also, everything work except for charging the battery. All parts are OEM from the dealer.
Thanks!

So let me confirm what you are saying. If the red lead is on the regulator B+ terminal and the black is on battery negative you have 0 volts. If the red lead is on regulator B+ and the black is on battery positive you have 12V. If that is true then the issue is someplace between regulator and were that wire goes. Could go to the battery side of the starter solenoid or to the keyswitch. If the red lead is on the regulator B+ and the black on battery negative and you have 12 volts then I would be making sure the ground strap that goes from one of the regulator screws to a engine screw is present.

You can also connect a wire from the B+ terminal on the regulator to the B+ terminal of the battery and then check battery voltage.

ILENGINE said:

So let me confirm what you are saying. If the red lead is on the regulator B+ terminal and the black is on battery negative you have 0 volts. If the red lead is on regulator B+ and the black is on battery positive you have 12V. If that is true then the issue is someplace between regulator and were that wire goes. Could go to the battery side of the starter solenoid or to the keyswitch. If the red lead is on the regulator B+ and the black on battery negative and you have 12 volts then I would be making sure the ground strap that goes from one of the regulator screws to a engine screw is present.

You can also connect a wire from the B+ terminal on the regulator to the B+ terminal of the battery and then check battery voltage.

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Ok I’ll check that as soon as I get home!

Also if the charge wire goes to the starter solenoid you might have it on the starter side of the solenoid.

StarTech said:

Also if the charge wire goes to the starter solenoid you might have it on the starter side of the solenoid.

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Is there a diagram of how the wires should connect? There are 2 posts and a single wire that connects like a spade connector.

Usually someone can look up and post the wiring diagram when the OP actually post the real model number from the equipment serial number tag. Multiple years with changes to wiring on different versions of the same mower line.

Model: STT61V-26CH-EFI Serial number: K1902835

IF that rectifier is mounted to the plastic blower housing check that the body has continuity to ground .
Kohler like to use a brass strip to connect the rectifier mounting screw to the bolt that holds the blower housing on and thus ground.
These fall off & also crack so there is no ground
The rectifier has 4 connection AC AC DC+ DC- .
Unless all are there, nothing back to the battery .
When I service one I always make 2 wires to connect both rectifier mounting screws to the engine to ensure a good ground.

It is possible I’m not getting ground. I’ll have to double check when I get back.

JW 1 said:

The DC wire shows no voltage.

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You need to figure out why the DC wire shows no voltage. It should always at least show battery voltage. Right now, you have no connection to the battery, and you can't charge a battery you're not connected to. The violet-colored wire runs from the B+ terminal of the regulator/rectifier directly to the same post on the starter solenoid that the positive battery cable connects to. That is it's connection to the battery. That violet wire has a 30-amp fuse in it that could be blown, or it could just be a bad connection. Either way, it's a fairly short wire with a fuse holder in it and could easily be replaced if need be.

JW 1 said:

It is possible I’m not getting ground. I’ll have to double check when I get back.

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Until you get battery voltage to the regulator/rectifier ground makes no difference. Once you get battery voltage to the regulator/rectifier, take your voltmeter, ground the black lead and touch the red lead to the metal part of the case of the regulator/rectifier. If you read voltage through the case, you know you have a ground problem. If there is no voltage apparent at the case, the ground is fine.

VegetiveSteam said:

You need to figure out why the DC wire shows no voltage. It should always at least show battery voltage. Right now, you have no connection to the battery, and you can't charge a battery you're not connected to. The violet-colored wire runs from the B+ terminal of the regulator/rectifier directly to the same post on the starter solenoid that the positive battery cable connects to. That is it's connection to the battery. That violet wire has a 30-amp fuse in it that could be blown, or it could just be a bad connection. Either way, it's a fairly short wire with a fuse holder in it and could easily be replaced if need be.

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Ok. Just curious but if the ground wire wasn’t grounded would that effect battery voltage from showing on the DC wire? I’m almost sure that the wires at the starter are connected correctly.

JW 1 said:

Ok. Just curious but if the ground wire wasn’t grounded would that effect battery voltage from showing on the DC wire? I’m almost sure that the wires at the starter are connected correctly.

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The suspected bad ground would be if the regulator/rectifier is grounded. That would have no effect on DC voltage on the B+ wire.

I guess to clarify, when you are checking for voltage at the B+ wire, where are you grounding the black lead of your meter? If you’re trying to ground it using the metal case of the regulator, then yes, a bad regulator ground could cause you to see no voltage on that wire. I always try to use the negative terminal of the battery as my ground. That’s your best ground.

I tried the negative and the positive. The negative didn’t show any reading. I will update you when I get back tonight.

Well I feel stupid! It turns out that I missed a fuse. 30amp near the starter. I guess my eye sight isn’t as good as I thought!

I would like to thank everyone for the excellent advice!

Glad it wasn't anything more serious. Thanks for sharing what you found.

Here's the IPL with wiring diagrams.

At some point up front you mentioned a new engine. There can be a chassis to engine variation in harness parts and a need to get an adapter so each wire in that bulk connector is proper.

This may help, or confuse the issue. Once engine is running, do you get AC voltage from AC wires? Then do you get DC voltage from DC wires? I agree ground is suspicious and needs be confirmed. I would charge the battery. Measure battery voltage before starting engine and record it. I would then start engine and record voltage again. If voltage at battery when running is not same or less than DC leads from regulator, yes it is a wire issue which needs be traced to where it stops being present. Hopes this helps. (2 cents) why did you change the regulator? Was this because of charging issue and maybe the old one was good and this is really a wire issue and the new component was not needed? I am concerned you replaced before measuring outputs of old stator/regulator.