Sounds like the 99 burb that i restored a couple winters ago.
Mine had an issue with the fuse powering the security system.Fuse tested good on the end while installed.But it was corroded on the spade and not getting clean power to the security system.I believe it;s the same fuse that powers the daytime running lights.
Hopefully you don't have to dive in as deep as i did.
My Burb had been abandoned,so i had no knowledge of it's issues.It had a bunch.
Ended up with a nice rust free 4x4 2500 Burb in the end.