Ecm wiring harness

[Jamescj212]

Had truck(2013 cascadia w/ cummins) taken into dealer for diag. Was throwing codes, i ran through list changing parts etc to no avail. When I'm out of options or ideas ill take in for diag, and go buy parts and do work myself as much as possible. Anyhow they come up with ecm harness which is $800 at cummins. If they were to put this harness on at truck country they want $1400 which isnt happening. A couple questions. Anyone changed this out before? Any ideas? Harness has about 15 connections. Any videos for something like this? I couldn't find anu. Thanks