1991 Cadillac Deville Battery dies after weeks of not being

All interior lights come on and go off with the opening and closing of the drivers door.

Now that you mention the door switch, we had the car on and turned it off but did not get out. Every thing in the car was off but we were hearing the noise. I will bet that if I had opened the car door it would have stopped. I just went out and sat in the car for 10 minutes and it was dead quiet. I will try to check the current draw tomorrow.
Thanks.

I measured the current draw on the Battery and the system is drawing 17.8Ma which is just about nothing.

In you last response, you incicated that if a Caddy sits form more than a week, the battery will be dead. Is this a normal function for this car? I would expect that a car should be able to sit a month or two without killing the battery. We went away for a whole 3 months before and my van started immediately as if we just drove it the day before.

The car seems to be runnin properly other than the battery draining down. I am not sure how long it takes for the battery to drain down however, I am just getting involved with my Dad's car after his death and we can't go back and ask him about this and my Mom thinks all cars look the same other than color. You get the idea.
Thanks for your help.
Dv

I'm not sure if anyone asked this or not, but I was wondering. How old is the Battery? I have a 94 Chevy pickup, and I bought it brand new, and after it's first battery went bad, (Around 4 years) it would do the same thing. As long as I drove it all the time, it was fine, but drive the wifes car for a week or two, trucks battery dead as a doornail. I'd push the truck down a hill, pop the clutch to start it, and it would charge back up and be fine, until I'd park it for a week or two again. Finally, I just got a new battery, and all that stopped.
Just a thought, and even if your battery is new, it could be defective as another user mentioned above.
Good Luck with it,
Jack