I have a John Deere lx172 mower. I started to have a problem with it a week or so ago. When I am mowing seems like everything is ok till I hit a bump, at this point the pto disengages and the blades shut off. I can then push the pto button down and then pull it back up and the pto will kick back in and operate properly until I either hit another bump or drive on a hill. At this point it will kick out again. I have replaced the pto switch and this didnt fix the problem. Any help I can get on this would be highly appreciated.
Two things immediately come to mind.
1) set switch ( or wiring to it ) activating which will cut off the blades
2) bad electrical connection to the PTO.
The wires have a habit of breaking just where they enter the actual PTO.
And thinking a little more you model might have a pair of relays hooked up to the seat switch.
One closes when the set is vacant the other closes when the seat is occupied.
I would add one thing to Berts reply, check your ground connection at both the battery and where it attaches to the frame. Make sure it is clean and tight.
