did you spray down the bike with a hose, directed at the left grip switch pod?
I think you should start at the major front harness plugs under the front left side fairing pocket, unplug and re-plug them all. Bad connections. Then move on to the J box plug, do the unplug/replug thing. and follow up with whacking the Jbox stoutly with the bike running. Gauges, Tach, neutral light, all quit working sounds like fuse issue.
I thinking the grip pod is the offender, it houses all the connections that would make signals and highbeam issue.