04 chevy impala 3.8fl

Your battery is supplying voltage to something. Pull each fuse one-by-one until you determine which circuit is the problem and the trace the wiring from there. You may need to connect an ammeter to the positive battery terminal and watch for when the current stops to tell you the circuit.

Your Impala has Retained Accessory Power or RAP for short. When you turn off the ignition you can listen to the radio, operate the windows, and use some other accessories for 10 minutes or until any door is opened, whichever comes first. Your Impala also has a battery run down protection feature. If you forget to shut off the interior lights, for example, the computer will automatically shut them off after 10 minutes of no activity. To test both features sit in the car for 10 minutes after shutting off the ignition. After exactly 10 minutes the radio display should go off and the windows should not work until you turn on the ignition again. To test the battery run down protection feature leave your interior lights on, exit and lock the vehicle. After exactly 10 minutes the lights should go off. If either of these tests fail the body control module or BCM is most likely bad. Hope that helps! Jim

Thanks thats a big help. I will try that in just a second.

Unplug the onstar module in the trunk... they crap out