[rsz71]

I know this thread has been going on for a while. I put a temp./compass/auto dim mirror in my '98 Z. The plug I got only had three wires. I ran a hot and ground and got the compass to work. I've acquired the correct 7 wire plug and I think by reading all of the posts I've got the wiring figured out.
What I don't know is where the B.U. wire or circuit is and where the best place to tie into it. Am I correct if you don't hook up the B.U. wire, it needs to tie to the ground or the auto dim will not work?

Thanks
Rob