where is the BCM on my 2001 monte carlo and how much will cost to repair/replace

It is behind left side of instrument panel. You need to pull it and call this number 877-687-3267. You don't repair it you replace it. If you buy one from the dealer or a parts house you will have to have it flashed (programed). The phone number I gave you provides a plug and play BCM. You need to provide the VIN, numbers on the BCM, and mileage. Spend $26.95 at this website and get step by step instructions on how to remove the BCM and anything else on your car for a whole year. Take slow and easy and you should be able to do this repair. Call that number first and make sure they can provide a remanufactured BCM. You need help email me at jmgrhm30@gmail.com.