Chevrolet Repair: 2001 Chevi Monte Carlo SS gone LOCO!, monte carlo ss, beam light

Question
Our Monte has been fantastic. Suddenly from one day to the next it's gone crazy. I went to drive it about 6 blocks to the library and the dome light was dim and flickering. The indicator (idiot) lights said, not necessarily in this order, service engine soon, high beam out, security and then the red picture of the battery comes on and gives 4 dings and the volt meter will crash for a few seconds and then pop back up to normal. It will then cycle through all these again and again and again. Much later that night I asked my husband to check it out. It was dead. The battery would not take a charge. We got a new batter and it started and ran great except it continued to cycle through the above problems. When off the dome light and map lights will not turn off. They stay on now. I had a diagnostic run and it came up with no codes at all. I have not yet had the alternator checked, but I highly doubt that is the problem. The alternator wouldn't make the lights suddenly stay on or say that the high beam is out when it is not. I really abhor spending hundreds if not thousands of dollars to have dealer or other mechanics systematically tell you it's this or that and fix it and that isn't the problem. I have a major problem just paying them to run a diagnostic. I think it's the BCM. Any ideas?? I love the car and in Minnesota it's getting cold and I want my heated seats! :-)

Answer
If you take it to a dealer hopefully they will be as highly trained as myself and they would tell you as I would tell you and as you assumed that it is your BCM.  Now I will also tell you that you are unable to replace it yourself.  The bcm needs to be programmed at the dealer using the tech 2.  After that is done the theftlock passlock system needs to be relearned.  The labor time for this job is probably 4hrs.  expect to spend 311 dollars plus the part.  I will also tell you that it will fix the dead battery and the dome lights and the high beam light and the alt light light.  If your heated seats are not working bcm replacement will probably not fix your heated seats.