Well... my manual is right here, let me look up the fuse situation...
Okay, so fuse #4 in the Ford (not the Chinook) fuse box by your left driver shin looks like the one. It's a busy one as it also does power locks w/RKE (not sure what RKE is), warning chime, modified vehicle, power mirrors, main light switch, and courtesy lamp. Significantly, I wrote in a note saying that this fuse also runs (ran, in my case) the start battery portion of the
Chinook added rear stereo. So that makes sense since you were working on the Chinook coach stereo.
Couple of notes: The "dome lights" seem to have some variety depending on year, but as yours and my Concourse are pretty close you may have the same setup as mine. The interior lighting scheme was slightly complicated on mine. It's basically all Ford, with the exception that I think the rear view mirror lights are part of a Chinook option (mirror with temp/compass/lights). Anyway, Ford did this thing called "illuminated entry." You may notice if you so much as breathe on your exterior door handles at night the interior dome lights all come on. That's illuminated entry. Also, when you open the door they all come on (whether you like it or not, I didn't). There were no buttons or options on mine to make them NOT come on. Real popular at star parties or when you just want to not display everything at night
My "dome" light is an oval fixture with two lights and two buttons - I've seen it in other Fords so that's why I say it's a Ford thing even though it is in the Chinook molded headliner.
BTW, I re-wired my dome lights so they CAN be kept from coming on. Basically, I eliminated the "illuminated entry" (so no longer can outsiders just touch my door handles and make my dome lights come on; why was that ever a good idea?), and made it more like what we are all used to where you can make them stay off altogether, come on when you open the door, or come on when you turn them on. Side benefit is I can now have my cab doors open but not have the dome lights on (that was not possible with the genius of illuminated entry
)
In summary, I think Ford fuse #4 is likely your culprit.
BG
PS: One thing to know is that with the one feed wire coming from fuse #4 to the coach radio, you are drawing some on your Ford start battery when camping and using the radio. I followed Bob W's example and moved that wire to a coach source. I like to keep coach loads on coach batts with no "sneakers." The only downside I know of is that if you turn your rig to "store" (thereby cutting house power), you'll lose radio presets. That was not a thing for me as I rarely "store" and can't really use presets that much when traveling anyway. Just something to consider.