I would look for the permanent magnets that send the signal to the cruise control about drive shaft speed. Sometimes the glued-on magnets get loose and fly off. Also, the sender unit must be close enough to the magnets for them to energize the sender unit. I don't exactly remember where to tell you to look, but someone else may.
2004 Tiffin Allegro 27.5 ft. P32 18,000 lb GVW. 8.1 liter. Workhorse chassis built May 2002. 24,500 miles. 2012 Jeep Liberty Toad. RVi2 brake unit.