I have the same problem on my passenger side vanity mirror. Sometimes the light will be on....sometimes not...if its not on....i'll smack it a couple of times, and the light will come on. I think it just has a life of its own...but it doesnt bother me. Im sure it would bother a date trying to check her makeup in the middle of the night--oh well...

Agron
1989 300E (108k miles)