Well I am going to say you may have to have a Pete dealer look at the wire harness. Your truck came with a Detroit so it was wired for one. Back in the day Pete wired each truck differently or engine spec. all they did was change some of the wire pins going to the ecm . The ecm may see you have turned on the cruise but it may not read the speed on the right wire pin so it cuts off the function.
Mine has a similar problem, but I have just figured it is the ecm, or the eaton vorad messing with it. if all the mechanical problems dont fix it, it could be a buggy ecm or the ecm is miss reading a sensor.
I have a 2013 peterbilt and the cruise keep kicking out for no reason does anyone know it may be . It does this for no reason Please help
Clutch pedal switch or adjustment/ return spring, brake pedal sticking or output yoke loose. In that order. Any speedo bounce?
Replace clutch switch brake switch on cruise control to work once it reaches 65mph it’s works for about 3 mints and then shuts off any info would help
