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I have a Kohler Command CH23 on a Deines Mower. When boosting the mower, I accidentally reversed polarity when boosting it (stupid I know). While it was reversed (and didn't realize it), when turning the key, I could hear something like possibly the starter turning backwards (but not engaging the engine). Don't know if it actually was turning backwards, just sounded that way. I then realized my mistake and corrected the polarity of the booster cables. But now when I went to start it, I turn the key to 'run' and it starts cranking and continues to crank even when engine starts. Acts like a stuck solenoid (only, it's not stuck). Quickly shut it off. But every time I turn the key to the run position (not the start), the starter starts turning the engine. What do you think I may have damaged?

I checked my solenoid with a volt/ohm meter thinking it's stuck in engaged position but it's not. So when I turn the key to 'run', I can hear the solenoid engage and the starter will start turning the engine to start it. I also pulled the ignition switch off and checked it's continuity and it appears to be working properly.

Any thoughts as to what might be wrong? Please give good detail, I'm no mechanic. Thanks so much for any help.

check for damaged wiring, insulation burnt off, all locations & use electrical tape, make sure all connections are tight & secure. you may want to remove starter, for Safety first remove negative ground from battery, for inspection & bench test.

do not remove starter, let Rivets weigh in on your electrical issue.

It's a nightmare to take the start off; need to pull the engine, and not easy to do that either (whole machine needs to be dismantled. But will check for burned wiring or loose connections. (didn't see any damage on the wiring on initial inspection. Thanks.

I would say there is a one way diode in the harness that controls the flow in the kohler harness that when you made the mistake it made diode blow now when you turn the key it doesn't know which way for it to flow those are replaceable I would just get the kohler harness replaced as it might have other damage to it.

Sounds to me the relay is fried, stuck on.

The solenoid is good, I put a VOM on it and it's dis-engaging when it loses power (plus you can hear the loud click when it engages). I'm starting to think that yeah, it may be the diode. So need to pull the engine out I guess. Thanks guys.

Check the starter solenoid trigger wire for voltage and if it has voltage when the ignition is turned on then there is a short in that wire or a relay that energizes that wire is shorted.
It is a bit difficult to go any deeper without a wiring diagram.
I am assuming you have a piggy back solenoid on the starter.

meteors63 said:

The solenoid is good, I put a VOM on it and it's dis-engaging when it loses power (plus you can hear the loud click when it engages). I'm starting to think that yeah, it may be the diode. So need to pull the engine out I guess. Thanks guys.

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But it is only supposed to be energized when the key is in the start position. Sounds like you said it was energized when the key is in the run position.

bertsmobile1 said:

Check the starter solenoid trigger wire for voltage and if it has voltage when the ignition is turned on then there is a short in that wire or a relay that energizes that wire is shorted.
It is a bit difficult to go any deeper without a wiring diagram.
I am assuming you have a piggy back solenoid on the starter.

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Could not see any voltage on what I believe to be the 'trigger wire' (blue). That one eems to be grounded (or a continuity close to ground). By a piggy back solenoid, I assume you mean it's physically attached to the starter? If so, yes it is.

I've attached a wiring diagram.

helomech said:

But it is only supposed to be energized when the key is in the start position. Sounds like you said it was energized when the key is in the run position.

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Yes that's right. When I turn the key to the 'run' position, I hear the solenoid click to engage the starter. Pretty sure that's only supposed to happen when I turn the key to the 'start' position, not 'run'. When key is off, there is no continuity across the two large terminals at the solenoid so it does appear to be 'stuck' on.

meteors63 said:

Could not see any voltage on what I believe to be the 'trigger wire' (blue). That one eems to be grounded (or a continuity close to ground). By a piggy back solenoid, I assume you mean it's physically attached to the starter? If so, yes it is.

I've attached a wiring diagram.

Click to expand...

If there is no voltage on the blue wire, that means the key is not the problem. Power has to be flowing through the relay to get to that starter.

meteors63 said:

Yes that's right. When I turn the key to the 'run' position, I hear the solenoid click to engage the starter. Pretty sure that's only supposed to happen when I turn the key to the 'start' position, not 'run'. When key is off, there is no continuity across the two large terminals at the solenoid so it does appear to be 'stuck' on.

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Sounds to me, like the solenoid/relay is burned closed.

But if it was burned closed, I should read a closed circuit when I put the VOM across the main posts, shouldn't I? But it shows an open circuit while the key is off. I can hear the clunk of the relay when I turn on the key (just as it starts cranking). Or am I out to lunch on this? I'm no mechanic so maybe I'm missing the point. Sorry about that.

meteors63 said:

But if it was burned closed, I should read a closed circuit when I put the VOM across the main posts, shouldn't I? But it shows an open circuit while the key is off. I can hear the clunk of the relay when I turn on the key (just as it starts cranking). Or am I out to lunch on this? I'm no mechanic so maybe I'm missing the point. Sorry about that.

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do not remove starter or anything else, be patient & let Rivets weigh in, bertsmobile 1 & ILENGINE, are all very knowledgeable Men!


do not pull engine, let Rivets weigh in on this one, he is a retired instructor, very knowledgeable troubleshooter. i'll send him a message regarding issue.

message sent!

OK thanks Mark!

meteors63 said:

OK thanks Mark!

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your quite welcome meteors63, hopefully Rivets will reply soon, he is a retired instructor & works for a Toro dealer in Wisconsin!

meteors63 said:

But if it was burned closed, I should read a closed circuit when I put the VOM across the main posts, shouldn't I? But it shows an open circuit while the key is off. I can hear the clunk of the relay when I turn on the key (just as it starts cranking). Or am I out to lunch on this? I'm no mechanic so maybe I'm missing the point. Sorry about that.

Click to expand...

Yes, but the power is coming from somewhere. The blue wire has to have power if the relay is pulling. There are only 2 sources of power going to this relay correct? From the battery, then from the switch. Maybe the key is fried, disconnect and check the blue for continuity with the key in the run position.

I agree with mark, don't pull the engine. the starter is working, something is telling it to turn on.

pull the key switch out and then pull the wiring plug through the hole so you can get to the wires.
To start the key switch connects the B = Battery wire to the S = Start wire.
'The letters are on the back of the switch.
To run the key switch should disconnect the S wire ( blue wire )
If the S is still connected to the B with the switch in run position then the switch is faulty

NExt you replace the switch with patch leads
Connect the B to the A & L terminals on the plug with the switch removed.
If the starter cranks then you have a problem in the wiring.

I bought a new ignition switch (key) but apparently I didn't need to. I tested both switches and they both work exactly the same (as as they should be working). But I have no "A" on m my key switches. Only G, B, M, L and S. In the OFF position, G and M or connected. In RUN, B and L or connected, and on the spring loaded START position, L, B, and S or connected. From what I've researched, that's the way they're supposed to work too. Hopefully this is right and I don't have TWO bad key switches.

I'm uploading a video of some of the things I've observed. Will post it as soon as I'm able to. Thanks guys.

SO as you know how the switch connects the wires, make the connections at the plug as per my previous post.
If the engine cranks with just the B & L connected then you have a short between the blue wire and a power wire.
There are 5/8 of SFA power wires on a mower, most circuits are ground circuits.
So it should not be hard to trace the wire back in the loom.

OK thanks. So it's likely back where I it's not easy to get at (in this case). Will need to tear the whole thing apart to get at it but glad we have an idea now.

Made a video showing what I've observed so far: https://youtu.be/twCNbZGTeW0

I suspect that when the jump was reversed it caused a backfeed of power through a wire that couldn't handle the amps and has now melted the wire from the key switch to whatever the L connects to to the wire going from the key switch to the small terminal on the starter solenoid. So I would be looking at the wiring harness for melted wires.

Disconnect the L wire from whatever it connects to on the mower, and the small wire at the starter solenoid. Now disconnect the wires connected at the key switch and take your ohm meter and put one lead on the S terminal wire at the key switch harness and the other lead on the L terminal of the key switch harness and see if you have continuity. Continuity means that they are most likely melted together. But what they are feeding needs to be disconnected to prevent a common ground from completing the circuit during the test. Also I would disconnect the battery while doing this test just to make sure something doesn't get crossed and cause other damage.

OK thanks very much ILENGINE. That's some good suggestions and I'll try that. I'll have to dismantle the machine a bit more to get at some of that. Thanks again to the others also for your suggestions. Great help of this forum. This is exactly what I was hoping for.

Diode in the kohler harness?

Luffydog said:

Diode in the kohler harness

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You were right. https://youtu.be/d7NCxM5TGEE

Thanks everyone to helped find this problem. Great forum and good guys. Cheers.

Did it start and run after you replaced the diode or harness? Glad you found the problem.

Still putting it all back together (had to yank the engine out). But so far with what I have back together, it's no longer cranking over in 'Run' and now only cranks over in 'Start'. Good sign but no, have not run it up yet. Hope to get to that later today or tomorrow. TNX

Sorry, forgot to update here. Confirmed that was the problem. Runs great, acts the way it's supposed to now. Thanks all for the help!