Thanks for your response.
I've read about that problem, but it didn't turn out to be mine. Got a
sub for Alldata.com, and had my answer in about 5 minutes. I had a bad
cigarette lighter fuse! Don't ask my why, but GM chose to tap off of
that fuse for a hot wire, in addition to the regular door lock fuse.
PUt in a new fuse, and I'm good to go! Go figure!