Nmea 2000 fuse ? Or malfunction

On my 4460, that bus and connection was behind the dashboard and the my Navi screen I used with it. I'm pretty sure on my 33 OBX it was behind the Marine Radio, but I never confirmed where it was on that boat. Regal is not consistent between models or even years of the same model on how they run the wiring. At least that was the case back in the early 2000s I helped a few folks with 4460s and their wiring issues and every one of them was a little bit different. To be honest what I usually did was find a connection and then track things back. It's a pain but it may be the only thing you can do. Your LS9 will be close to my 33 OBX, so I'd start with the Marine radio.