Freightliner Cascadia 125 - Truck turns off going down road or idling

Mine would intermittently shut off after hitting pot holes,and it was a loose battery post.

 

Follow this T/S. Since you didn't give last 6 of vin, I am only ASSuming you have a Classic Cascadia. In this case, it would have a CPC4. The T/S would be very similar. Therefore, I'm only fairly confident your #2 connector, pin 1 is the same. Should be CIRC 439C printed on grey wire that goes to BHA connector.


In addition, I would check your cuttoff switch wiring to the PNDB. This has been a known corrosion spot.

 

Does all the power go off when it happens?

I've had to replace the power distribution module on both of the Cascadias I've owned. In both cases I'd be driving along and suddenly everything would go dark and the engine would quit. The a second later it would all come back. New PDM fixed it both times.