Ecm swap

[Perro903]

Great evening folks, question. Had isx15 come in with erratic voltages coming out of ecm. Was getting 8.5 v coming out on signal return for turbo speed, .29v 5 volt for intake manifold pressure and temp. So I decided just to change ecm. Me thinking I knew it would work just reflashed another ecm with. Not the same part number, didnt have the same cal but both were cm2350. The good ecm was off an international manual transmission. Bad ecm kw auto transmission. No codes and It worked fine until the driver got loaded. It came back with spn-639 j1939 network #1 primary vehicle network. Something around the lines of transmissikn wrong channel as I'm out sick today and can't exactly remember. Advise on what I did wrong?