94 e320 rear dome light issue

[lafooy]

don't know where to start troubleshooting really, so any help would be appreciated. rear dome light does not turn on when open a rear door or with dash switch. it only barely goes on when the truck is open, not sure if it is supposed to do that at all. the following maybe be tied to this ... sun roof doesn't work so i unplugged it, power antenna doesn't work either ... the dash rear light switch does however turn on the lower lights that are on the bottom part of the rear doors. these have been like this since i bought the car a few yrs ago