I have a 935F John Deere diesel mower, It won't do anything no current to switch and I want to know if there is a fuseable link that I can check

See link.

https://www.google.com/search?q=5202+john+deere+diesel+ignition+switch+wiring+diagram

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Repair your vehicle right away. Just click on the link I attach.
John Deere 2653A Diesel Professional Utility Mower Workshop Repair Service...

John Deere Riding Mowers
Richard, Check the attached links,instruction and guides for wiring diagram. Good luck
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it probably blew a fuse check them and check the positive wires some have a fuseable link looks like a rubber joiner in the line check with test light on both sides of link good luck

check your seat safety switch

The battery cable goes to the starter solenoid. From there the wire leaving the starter solenoid should have the fuse in it near the solenoid.

Park brake switch is the most likely culprit,any other would cause the tractor to not turn over in the crank position.

To check pump u remove fender deck,unhook connector, put 12 volt power to it.I have seen pumps react to a swift kick to the fuel tank,NO JOKE.You first have to check fuses,2 on control board and early x585 machines had a single red wire near control board that was only for fuel pump.Remove right side air screen and check for voltage on the relay closest to the radiator.Red wires #231/232 feed your fuel pump relay.Current flows from that relay #655 pink wire and goes to your fuel pump .Also check#215 grey wire {fuseable link}coming from starter post,they WILL burn out,it goes to #221 red wire with inline fuse and feeds rear of the 2 relays,that is your EFI relay.You have 3 fuseable links coming off starter post,check all of them.

... should be between operators seat and 3rd link arm. A large nut/cap on top of the transmission cover, near the rockshaft of the 3-point hitch arms.

I’m happy to assist further over the phone at https://www.6ya.com/expert/rolandw_c013176d62ee17ae