F&9 = open shunt field fuse

also could be faulty wire connections, open shunt field, shorted T351 transistor, or logics defect.

the flow chart mentions the driver board, this could also be the cause.

check connections:
check field shunt fuse, replace if open

check continuity of wire #34 from line contactor to logics P12-4, wire #71.
7 to 10 ohms? check driver board, no continuity? repair wires or connections

check driver board (field shunt components only)
not failed? replace logics
failed? replace driver board.

Thanks, I will look into this SER#4YJ00363

It would help to post the serial number. I think this is a micro command system. Code F-9 could be a blown shunt field fuse. The fuse should be a small glass (10 amp ? ) located in the rear panel upper right corner. The wire number should be 34. I would look there first and inspect wiring from it. Sometimes replacing the fuse is all it takes. Post your results and let me know if you need more information to dig deeper.