Car battery dies overnight

I have a 2003 Impala with 76,000 miles and experiencing some strange problems. It started with the marker lights in the front and rear of the car flashing at night when it was pretty cold out. Car still worked fine at this point though. Then when that quit all on its own, the trunk latch would pop and/or the dorr locks would unlock while you are driving. Car still started and drove fine. Now the battery drains overnight and is dead in the morning and wouldn't start. It wouldn't start with jumper cables either. Had to use a jump box, and it still didn't turn over right away.
In the past few months I have changed the heater core, radiator, starter, battery, brake pads, oil & filter, transmission fluid and filter, plugs and wires. Can anyone offer any help. I like the car, but it is driving me crazy.

Lights acting up, trunk latch acting up and dieing over night.Where's CovertCelery to say it when you need him :iceslolan: Sounds like your BCM's on the way out.

Actually Mine was doing the Dieing over night thing when my BCM Took a dump. Try this. On the driver side Fuse panel Find the 10A CLSTER/BCM Fuse (Is Red one beside the grey relay), and pull it when you park it for the night. Then go back in the mornin, stick it back in and see if you have juice.

With the new battery, and I disconnected the trunk latch, I had power this morning. Still think your right, someone else told me about the BCM yesterday. Looked it up in a wiring diagram and it controls everything that has been going strange with my car.
Do you know where it is located, what it costs to replace. I looked it up, its about $100. I would put it in myself, but I heard it needs programmed after you put it in.

It does need programmed. The dealer or someone with a TechII can do it for you. What most people do is drive the car to the shop, remove the old BCM in the parking lot, install the new one and have the mechanic come out with the TechII. That way, you don't pay for their labor to remove and replace it. The BCM is located about where the drivers left knee is, under the dash on the side of the car. It's pretty easy to get to and install.

Ya I'd do was Flylow suggested. Find a dealer that's cool with it, and drive it there, swap em out and have them program it. Your looking probably 80$ for programming.

Here's a picture to help you with its location:
http://i232.photobucket.com/albums/ee46/MaImpala/100_5524.jpg

And heres kinda what it looks like (I know its hard to see):
http://i232.photobucket.com/albums/ee46/MaImpala/100_5529.jpg