# Kohler CV20 won't shut off



## Buck Jordan (Feb 16, 2020)

I have a Simplicity Prestige with a Kohler CV20 engine. The engine will not turn off.
I have replaced the ignition switch. I replaced the wires from the coils to a switch so I could bypass the key and ground the coils via the switch. If I throw the switch one cylinder stops firing
I have disconnected one spark plug at a time and tried to shut down. One plug off will shut down but *not* if I take off the other and reconnect the first. I suspect one coil is bad. Have you ever encountered this ?


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## FredM (Nov 18, 2015)

did you make a complete new kill wire harness from the coils to the new kill switch?, or did you just join the new kill wire to the old harness from the coils, it is possible that one wire from the coil that wont shut down could be open circuit, that is the copper internals have come apart inside the insulation.

If both cylinders are firing, then the coils are ok.

https://www.kohler-engine-parts.ope..._page=document_general_info&products_id=34596

If you don't have a manual, open the above link and scroll down to the CV20 vertical shaft section and save to desktop, will show what you need to know.


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## Buck Jordan (Feb 16, 2020)

FredM said:


> did you make a complete new kill wire harness from the coils to the new kill switch?, or did you just join the new kill wire to the old harness from the coils, it is possible that one wire from the coil that wont shut down could be open circuit, that is the copper internals have come apart inside the insulation.
> 
> If both cylinders are firing, then the coils are ok.
> 
> ...


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## Buck Jordan (Feb 16, 2020)

The wires are all brand new all the way to neg /batterythrough new switch,the wires from the coils are soldered together near the coilsso they become 1 wire goingto the switch.


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## FredM (Nov 18, 2015)

Can you make up a couple of temporary kill wires that can be attached to each coil and the other end stripped of the insulation, start the engine and ground each wire in turn and see what the outcome is, if you had a multi meter you could check continuity of the kill wire at each branch to save having to make a couple of wires.


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## Bob Driver (Nov 1, 2017)

Look very carefully at the white wire running to the magnetos you may have removed. Some of the Command Pro engines had diodes in them just like a Briggs V-twin. The purpose was to protect the magnetos from each other. They're usually buried under a piece of heat shrink

Kohler was kind of sneaky about those diodes on the Command Pro engines. If you come across them in a wiring diagram, it will usually say "Optional"

Go to page 6 of the Lawn Mower manuals on this forum. Download *Kohler Electrical Trouble-shooting Guide*. Look at the 15 amp charging circuit diagram at the top of page 30 ("Optional Diode").

Like a Briggs, the symptom of a bad diode is that 1 cylinder dies and the other one doesn't. Also like a Briggs, *BOTH* diodes have be in circuit. Both Kohler and Briggs want you buy a $20 wiring harness for the repair. I use 1n4007 diodes (1A, 1,000 peak volts). A pack of 100 is around $5 on E-bay, or Amazon. Use two of these, a soldering iron, heat shrink, and make a new mag wire.


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## Buck Jordan (Feb 16, 2020)

I replaced the coil to the right cylinder and that solved the problem. Must have had internal problems. Now it shuts off instantly.


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