If it's doing it all the time that's a good thing Chucko! With a scan tool I like to see what modules I can communicate with, and then start unhooking every module that's on the bus one a time. Sometimes you get lucky and when you unhook the affected module (which can also take some of the associated sensors in the circuit out of the loop) the system will come back up and at least you'll have some direction in which to look.

The "no bus" can also act like windows. You might unhook something, everything starts to work, plug it back in.....and everything still works. That's why this is one of those "hated" issues. You might work on a customer ride for two hours, and suddenly "poof"...everything works.