If i change my bcm will existing key and its resistance code work ?? (92deville)

 

BCM and ECM have nothing to do with the basic VATS system, so you can change them at will. VATS module recieve signals from ignition cylinder and sends enable code to ECM to allow car to start. If you get FSM and understand how VATS works you may figure out how to defeat it even if module is bad. Module is burnt in (perminently) with key blank value as soon as key is turned to start. Therefore used is tuff 17 possible blanks, new don't even dream you could return it. 90+% of the time lock cylinder is the cause. You will pretty much need to remove dash to get to VATS module.

 

Then we will just have to remove the dash. I personally don't like getting reemed by dealerships or car dealers.