My 1999 Cadillac ETC electric windows and sunroof have stopped working, I am no longer able to open either of them.

As I understand it, both the windows and sunroof are controlled by a common in-line relay, rather than a fuse? In the event that the relay should becomes wet, the leads can corrode preventing proper function.

I am wondering if my understanding in correct, and where I might find the window/sunroof relay? I have taken out the back seat and decorative trunk panels, but have not been able to locate the relay. Any help would be greatly appreciated!"