I finally figured out that my rear defogger wasn't working because the previous owner pulled the relay...probably when he tinted the windows. I want to put one back there but I'm not sure what the part number is.
My car is a 96'. If you just looked in your fuse box at position 10 you could probably get the number. Realoem doesn't list a "rear defogger" relay.
http://www.realoem.com/bmw/showparts...66&hg=61&fg=25