List what changes you have made.
Like did you changed the seats?were they power seats with memory? Heat?
Did you chge the sound system for an aftermarket?
A lot of functions are cotrolled by the body module, and it is control area networked together. some alterations may or may not affect your desired functions of any or all units.
Post more info about what you are trying to do,what unit are you using that has bluetooth, an IPOD or ?