Jake brake on or off driving on flats or small hills?

Holstien13, When we first got the coach I took it to Cummins for reprogramming. They found that the program didn't change the way it operated so they called Holiday Rambler who said that it is wired to operate the way it is.

I called HR to get a wiring diagram and ask for help. They said they could not tell me how to change it for safety/legal reasons and the diagram they sent was a point to point wire map not a ladder/logic diagram so it is hard to figure out. It remains the way it is.