the AV is embedded with all the controls on the car. the BCM uses the CAN network in the car to talk to all the sensors and the AV is in the mix because you can change the HVAC settings and they show up on the screen. you can even TALK to the car and TELL it what temp you want! so yea the AV does play in this game.
i understand why the dealer is suggesting to replace the AV first, because it could be damaged and could be throwing all sorts of incorrect codes and also could be keeping the BCM and other modules from relaying proper data through the CAN system.
And please, with all due respect my new friend

, the armada is one of _THE_ most reliable cars on the road today! YOU had an isolated incident. please do not be so quick to judge the car based on your one isolated incident. what has happened to you is not a common issue with these cars.
but, yeah, i agree with the dealer on this one. i totally see their point....