# Issue with John Deere riding lawn mower



## Drachenfire (Jun 6, 2017)

My neighbor has a John Deere LA115 riding lawn mower.

Every time they cold start it they have to jump it with a battery charger.

Once the engine is hot, it starts normally but if the engine cools down, it has to be jumped again to start.

They have replaced the battery once already.

I put a volt meter to the battery while it was running and it reads 14.2V indicating the battery is charging.

Shut down the engine and waited a couple of hours. I checked the battery and it reads 12.3V, yet when they tried to start it, the engine would not crank.

I did notice they I could here a click when the key is turned and it sounds like the bendix in the starting motor clicking.

I am theorizing that when the engine is cold, something is sticking in the starter preventing it from turning unless it gets extra voltage from the jump with the battery charger. Whatever it is seems to loosen up when the engine is hot allowing it to start normally.

Is the theory valid or could there be another option?


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## HenryMac (Sep 12, 2018)

I'd take the battery out and have it checked... regardless if it was just replaced.


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## Drachenfire (Jun 6, 2017)

Forgot to mention, the engine is a B&S 31P77 0144 B1


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## joed (Mar 13, 2005)

Could be something in the charging circuit discharging the battery. A fully charged 12 volt battery should read 13.5 volts.


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## Nealtw (Jun 22, 2017)




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## Drachenfire (Jun 6, 2017)

HenryMac said:


> I'd take the battery out and have it checked... regardless if it was just replaced.


Two different batteries and the mower having the same issue?

I have checked the battery, it shows 12.2V with or without being connected to the mower. 

When the problem persisted after initially installing the new battery, they took it back to the store they bought it at which tested it and the battery tested good.


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## Nealtw (Jun 22, 2017)

A loose ground connection can tighten up when the engine is warm.


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## rooster4321 (Feb 25, 2018)

Check cables to starter both positive and ground

Sent from my KYOCERA-E6560 using Tapatalk


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## Drachenfire (Jun 6, 2017)

joed said:


> Could be something in the charging circuit discharging the battery. A fully charged 12 volt battery should read 13.5 volts.


Actually a good battery will have a reading of anywhere between 12 and 13V. Therefore 12.2V would not be unusual. 

I just re-installed the the battery on my 24-year-old MTD. It spent the winter on a battery maintainer. When I checked it prior to installation, it read 12.3V. I installed it, the engine cranked about 7 or 8 times and fired right up. 

*@Nealtw*

Thanks for the tip. I will need to test the solenoid tomorrow and see what happens.


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## lenaitch (Feb 10, 2014)

Just a shot but most lawn tractors have several safety switches (PTO, seat, gear selector, etc.) that are basically series switches in the primary side of the start circuit. The only one that comes to mind that might be heat-related is the PTO clutch. I don't know if that JD would have them before or after the ignition switch. If you can 'hot wire the primary and it works cold and hot you could narrow down the issue. I wouldn't recommend permanently by-passing the safety switches.
If not that, perhaps a carb/choke issue?


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## joed (Mar 13, 2005)

It's not a safety switch if a jump start makes it go. It sounds like a battery with very low power, not enough cranking amps to turn the machine over.

Try measuring the battery voltage while you try to start it.

Also try cleaning the battery connections.


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## lenaitch (Feb 10, 2014)

joed said:


> It's not a safety switch if a jump start makes it go. It sounds like a battery with very low power, not enough cranking amps to turn the machine over.
> 
> Try measuring the battery voltage while you try to start it.
> 
> Also try cleaning the battery connections.



It could be if you get voltage drops across the switch(es) caused by dirt, etc. They can be minor but cumulative since they are often multiple switches. Had it on both my JD lawn tractor and New Holland real tractor. Solved in both cases with a relay kit.


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## HenryMac (Sep 12, 2018)

Drachenfire said:


> Two different batteries and the mower having the same issue?
> 
> I have checked the battery, it shows 12.2V with or without being connected to the mower.
> 
> When the problem persisted after initially installing the new battery, they took it back to the store they bought it at which tested it and the battery tested good.


I had a '70 Nova do the same thing. Old battery expired bought a new one. Lights worked, radio worked, but it wouldn't crank over unless jump started.

Took it back, they said it was fine. Come to find out it had a loose cell inside the new battery.

Not saying that's the issue... just sharing similar experience.

Good luck.. be sure to let us know what you find the gremlin was.


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## Drachenfire (Jun 6, 2017)

Problem has been solved.

As it turns out it was the solenoid. $14 at the local John Deere dealership, 15 minutes to change it and the mower fired right up.

Thanks to everyone for their input and suggestions.


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