When leaving a campground the transmission on my 2005,Itasca 40 AD locked into 3rd gear and no matter what I did would not change. After getting over my panic attack (I just spent 7,000. on repairs last month) I called Allison Transmission and with the help of a very knowledgeable technician had me on the road again in about 20, minutes. He had me push a series of combination numbers on the control panel and all of a sudden everthing went perfectly.
My point, should you have transmission problems,call Allison first and if that doesn't work you may then panic.
Don, WIT 70041