BCM memory

My 2000 LS will not remember my programmed radio settings for automatic door locks, alarm, chirp, etc. As soon as the retained power goes off they all revert back to the default settings with the displayed asterick. Anyone have any idea what causes this? Is there a constant 12v line to the BCM for memory that has a fuse or maybe a connection problem?
Thanks for your help

Anyone? A schematic or block diagram showing pinouts of the BCM would help. Thanks

go to NAIOA and ask the same question
(north american impala owners association)