That sender is tripped by your reverse cable. The cable lifts a lever which in turn leleases from a groove in the shift drum to allow it to turn and engage the reverse shift fork. While it is in any gear the switch (sender) is open. The switch has to close to give the ECM the 'go ahead' to let the transmission to go into reverse. So ideally, there is no way for the angle sensor or gear position switch to show the ECM it is in reverse. And since the switch is naturally open in any other gear, there is no way for the ECM to know there is a problem when a wire is broken.
That is how I arrived a the sender being bad after reading your post.
I guess if Honda would change the system to a normally closed style instead of normally open, The ECM could have been aware of a code

----- Gimpster -----

 

I don't know how the gear system is built in the transmission, but it is bizarre that the angle sensor can tell in which gear it is but not the reverse one. It means that the angle sensor has a limited role.