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Discussion Starter #1
A couple of years ago I upgraded my 812 with a Kohler M 20 Twin. After installing the engine I removed the 812's old wiring harness, ignition switch, regulator and I replaced it with the complete wiring harness from the donor tractor which was a 20G. It ran well until this past summer where I began to have intermittent ignition issues. I parked it and began doing my mowing with my L-8. I decided to fix the 812 and now I have no spark at all. Then engine cranks but has no spark. The magneto is good as If I unplug the kill wire at the magneto I can crank the engine and both plugs have a strong bright spark. With the harness connected I can crank the engine and have no spark. I have inspected every inch of the harness looking for any place there could be grounding. The harness has never been cut or modified. Nothing found. I replaced the ignition switch (P/N19233) with a known good switch (19233) and no change. All of the safety switches in the seat, PTO clutch lever and forward/reverse lever have been jumped and there is a verified complete circuit there. There is a relay (40216) and a time delay module (P/N 40313) that came with the harness. Could one or both of these have failed? This is the seemingly last place to look for the issue. Any suggestions on how I can further troubleshoot the thing?. Thanks.
 

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I’d test the relay. YouTube has videos on how to do so. If it’s good, might be your time delay switch.
 

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Discussion Starter #3
Thanks for the reply. I have a shop manual for the G Series tractors. Has everything I need to finish the troubleshooting. I pulled the relay and tested it and it appears to be good. I have not had time yet to go on to the time delay module. I am first going to check all of the interlock sites to be sure the switches (although I have them jumped) are functioning correctly and follow the checks right down the harness to the relay and time delay. We'll see.
 

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Inveterate Putterer
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I'm betting on the time delay module. I've had similar issues. I jumped the module and all was good - except no safety, which was not good. The replacement module is kinda pricey, even for used.
 
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Gravely1964
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They were around $100 or so the last one I changed at work. Im sure they've gone up in price
 

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A couple of years ago I upgraded my 812 with a Kohler M 20 Twin. After installing the engine I removed the 812's old wiring harness, ignition switch, regulator and I replaced it with the complete wiring harness from the donor tractor which was a 20G. It ran well until this past summer where I began to have intermittent ignition issues. I parked it and began doing my mowing with my L-8. I decided to fix the 812 and now I have no spark at all. Then engine cranks but has no spark. The magneto is good as If I unplug the kill wire at the magneto I can crank the engine and both plugs have a strong bright spark. With the harness connected I can crank the engine and have no spark. I have inspected every inch of the harness looking for any place there could be grounding. The harness has never been cut or modified. Nothing found. I replaced the ignition switch (P/N19233) with a known good switch (19233) and no change. All of the safety switches in the seat, PTO clutch lever and forward/reverse lever have been jumped and there is a verified complete circuit there. There is a relay (40216) and a time delay module (P/N 40313) that came with the harness. Could one or both of these have failed? This is the seemingly last place to look for the issue. Any suggestions on how I can further troubleshoot the thing?. Thanks.
How old is that 812? Did you ever check the condenser?
 

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Treefarm
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Sounds like you have eliminated all the potential issues except the module. The only other thing that really bit me once was a failed diode but I’m guessing there is not one in your circuit to worry about. Hope you get it solved soon.
 
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