2011 Sierra 4l80 Swap

[luisdavid11]

2011 Sierra 4.8 originally was 4l60 and just swapped over to 4l80. It is rewired, flash 80e file off a van and it is stuck in 2nd gear/limp mode however speedometer works fine. Flash stock 4l60 tcm file back in, trans goes back to normal however speedometer only gets to 9mph then falls to 0 (OSS signal also drops to 0) and trans wont shift. Anyone ran into this issue before? Thanks.

[blindsquirrel]

Are you able to post the before and after tune files?

If you used the common 2008 Express van file (early), that's why it doesn't work with a 2011 ECM (late).

[luisdavid11]

i feel it's an issue with the wiring or something like that. put an early e38 off a 2008 suburban and same thing, t42 with 80e OS shows 2nd gear. Flash 60e tune to T42, goes back into 1st gear but speedo reaches 10-11 mph and just instantly dies. Speedo works perfectly fine with the t42 and 80e OS but stuck in 2nd

[blindsquirrel]

You feel it's an issue with the wiring and the only info you can give is "it is rewired"? So this is just like a blog post where you talk about things going on in your life, or you want to post some actual information - documents, diagrams, files - other people can look at to try to spot a problem?