This 2012 Cascadia has had an issue with shutting off at highway speeds. After changing all the usual filters and checking glove box and under hood fuses, someone suggested I check the battery box inline fuse. What am I looking for here?
A shut off switch that you rotate 90°, a Cascadia I drove had one next to the driver seat on the floor as soon as you open the door. Or mounted to the box itself near the batteries.
Bang the ecm with the handle of a large screwdriver while idling ... see if it cuts out.
Not sure about the CM2250's.. (it being a 2012 model truck).. but the CM871's were bad about this if no one bothered to change out the crank shaft damper when it was due at 500k miles ... then it caused the ecm to become flaky/intermittent. - Neglecting egr/engine tune-up work, etc. and ignoring regular required maintenance when its due is a major contributor of a lot of problems with these newer engines.
cascadia with cummins engine or dd15, does it start right away when shuts down?
if dd15 manual or auto?
Don't forget about a possible wore key switch (especially if you have some weight in keys hanging off the ignition) as well as the Power Distribution Module. It's located on the driver's side firewall behind the large group of multi-colored airlines. This was a fairly common issue with Cascadias....
Here's a quick video that explains it...
https://www.youtube.com/watch?v=FL3Ta3WsCN0