07-26-2018,
09 prostar here. It started 2-3 months ago and it progressively got worse. While cruising it suddenly disengages, the "cruise set" disapears from the screen, like when you press off, and it won't engage back if i press on until it randomly decides to re-engage when i press it again. Engine brake works. To me it seems like some connection is overheating and needs to cool down. Now it got to the point where it cruises for anywhere from 5 to 30 min then won't engage for 20 min or 30 or 5. It's random and it bugs me.I can't seem to find any fuse related to cruise control altough i pulled out and cleaned every single fuse. I checked the brake and clutch switches but they seem to work properly. I asked my friend whos a electrical engineer at navistar and he said it might be software related. Anyone had similar issues? Thanks to all and safe travels!