The starting system uses a direct path from the key switch to the neutral safety switch Starter Relay (K01) : Receives power if the tractor is in neutral. Primary Fuse (F101) protects the starting solenoid and ignition circuit. JustAnswer Important Note
The 6400's electrical system centers on a 12-volt DC negative-ground circuit. fuse and wiring diagram for 6400 john deere tractor 2021