This is from memory based on title for 650k Series 2, not by researching serial number, so take it for what it may be worth.
The drive train controller is under the LH arm rest, there should be plastic cover panel with 4 screws on it.
120 ohms supports the can fault being observed. Normal healthy J1939 canbus is typically 60, so one of the canbus end-nodes is not present/open-circuit likely by either faulty electrical wiring connection or bad component.
Also, as Gary mentioned in post #2 in this thread, check all of the fuses and relays 1-by-1 for corrosion as that can cause a variety of issues