Re: I-77 elavation change????
I do realize I should know my equipment. But living in South Western Ontario...it is very flat, just like Ohio. So the only opportunity we get to drive different grades is when we cross the border and go over the bridge. And I don't think we've ever paid attention about engine breaking there!
You don't need downgrades to check out the engine braking. Just drive on a level road about 30 MPH/50 kPH in a low gear and then lift your foot with the system active. You should be able to tell right away if the bus wants to keep going or drag to a stop.
On the other hand, as far as I know the various braking systems are all extra-cost options, and if you got your bus was local, it may have been ordered without anything. I don't think they are advised for use on ice, and the local transportation director may have tried to save money and avoid problems. If there's no control switch or shifter position, I would guess it was omitted. I don't see a picture of your instrument panel in the gallery.
Someone said "Making good decisions comes from experience, experience comes from bad decisions." I say there are three kinds of people: those who learn from their mistakes, those who learn from the mistakes of others, and those who never learn.