# John Deere LA 165



## Learn (Oct 5, 2021)

I have the subject tractor and when it’s running and I engage the blades it will stall and shut off.
Any thoughts on a fix would be appreciated. Thanks


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## Bob Driver (Nov 1, 2017)

Learn said:


> I have the subject tractor and when it’s running and I engage the blades it will stall and shut off.
> Any thoughts on a fix would be appreciated. Thanks


The "Blades" are wired into a safety circuit through two switches.... Seat switch and Brake switch. Both switches have to be closed (brakes released, seat occupied) or they ground the magneto(s) and the engines dies. The usual suspect is the brake switch, because it's located under the floorboard and is exposed to moisture and debris from the mowing environment. 

It's a 4-prong switch. One side is NO (normally open) and the other is NC (normally closed). They NO side is wired into the cranking circuit to the starter relay and requires you to push the brake pedal down to crank the engine. The NC side takes over when the engine is running, the brake pedal is up (released), and the blades are engaged (PTO switch engaged). It is tied to the magneto ground circuit through the seat switch and PTO switch (lever). 

The purpose of this wiring design is to kill a running engine if you are not in the seat with the blades engaged, and on some models with just a running engine. 

John Deere usually uses Part # GY20094, with "Push-In" type mounting clips. The clips get loose, or break over time, and the switch can't function. A sign the clips are loose is that you have to really "stomp" down on the brake pedal to get the engine to crank.

Push-In Brake Switch -- Stens #430-550


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## Learn (Oct 5, 2021)

Bob Driver said:


> The "Blades" are wired into a safety circuit through two switches.... Seat switch and Brake switch. Both switches have to be closed (brakes released, seat occupied) or they ground the magneto(s) and the engines dies. The usual suspect is the brake switch, because it's located under the floorboard and is exposed to moisture and debris from the mowing environment.
> 
> It's a 4-prong switch. One side is NO (normally open) and the other is NC (normally closed). They NO side is wired into the cranking circuit to the starter relay and requires you to push the brake pedal down to crank the engine. The NC side takes over when the engine is running, the brake pedal is up (released), and the blades are engaged (PTO switch engaged). It is tied to the magneto ground circuit through the seat switch and PTO switch (lever).
> 
> ...


Thanks for the great detailed advise. Will check it out.


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