My girlfriend watched a live-action horror/thriller movie on television in the early 1990's and is trying to figure out the name of it. All she remembers is that there was a little girl around 8 to 10 years of age. She thinks the little girl's name was Cindy or Sydney or something phonetically similar to that. There was also a very short obese middle aged woman with a "high pitched scratchy voice" who took the little girl to a large dimly lit fog filled room. She believes the woman may have been imaginary, or possibly a ghost. She also seems to recall a multi-level garage at some point in the story-line.
I believe the name of the movie you are looking for is Poltergeist 3. The little girl's name was Carol Anne.
Some weird facts about the movie is, the little girl who played Carol Anne (Heather O'Rourke) died shortly after the movie was released from some type of infection (IMDB says it was misdiagnosed Crohn's disease). Also, the scene in the garage you are talking about was done in live action. They didn't use special effects to create it.