ECM usually refers to the Engine Control Module (computer), but I'm guessing you are referring to either the Energy Management System (EMS) that sheds loads to stay under 30A when on 30A shore power. Or is it something else?
The EMS is part of the load center (breaker panel) and is accessed as ga traveler describes.
Former owner of 2004 American Tradition and several other RVs
Home is in the Ocala Nat'l Forest near Ocala, FL