I found this interactive electrical pictorial on the Sprinter forum. It works for a variety of Sprinter based Roadtreks. Someone with the skills (it's written in JavaScript) and some free time should create something like this for the Interstate. Take a look and try the buttons on the left side;
http://www.metrotrekkers.org/utility/electrical.htm The SEP/BYPASS mode might be pretty close to what the Interstate has but I haven't checked it out completely. The notes (link at the top) are worth a read also. What would be really cool is for someone to do this up to be run as a standalone program.
Wayne
Linear Mode
