Sometimes, diagnosing interior CAN problems can be simple. I've seen many cases where just an SDS "Quick-Test" reveals the culprit. Since the control units on the interior CAN network often rely on data from other control units, you may find several control units reporting communication problems with a specific unit. For example, if the seat, climate control, and domelamp control units all report communication faults with the right rear door control module, it's a safe bet that you've found the problem.

As far as the dealer goes, only a small percentage of technicians are really good at diagnosing CAN problems. If you go that route, let your SA know you need an "A" tech, not the alignment guy.