DDEC X DD15 625 FMI 14

[PolishHammer]

What year was the original engine and what is is the new one installed ? What was the failure of the old engine? Something isnt adding up here. This seems like a software issues because of the communication issues. The other issue is the de mandate. If both the mcm and acm from the original engine are not used you will have the communication issues.

Are you able to reflash the mcm and acm back to a stock file ?

Another question can you idle the truck up with the cruise ship to fast idle switch?