Hmm, we have a similar interior light malfunction on our 2004 coupe that I'm trying to diagnose. Cabin switch at rearview to off...and all lights stay off. But turn to auto, and they stay on...eternally, regardless of door position or lock status. The exterior lights do flash on fob lock and the headlights switch works fine (we haven't tried the fogs yet). Is there a separate interior lighting relay I could check?
I also imagine that it could be a bad door switch, maybe I'll look there first.
Several thanks,
Brian