Transmission swap 8l90 2018 to 2016

[Jessiebandz]

Hey so I’m having some issues on a recent job I had done . I bought a new reman 2018 Denali 8l90 trans from market place for a steal I thought it would plug and play on my 16 but I’m finding out it’s not as easy . I have taken it to get programmed but they said they were unable to get it programmed and but really couldn’t explain why. I read somewhere that 17 and up denalis had a different tcm? Could that be the source to my issue? I’ve had 2 shops unable to get it tuned .( won’t start either after Trans install) should I just call this a loss and look for one specifically for a 16? Thanks!

[newdude]

46 minutes ago, Jessiebandz said:

Hey so I’m having some issues on a recent job I had done . I bought a new reman 2018 Denali 8l90 trans from market place for a steal I thought it would plug and play on my 16 but I’m finding out it’s not as easy . I have taken it to get programmed but they said they were unable to get it programmed and but really couldn’t explain why. I read somewhere that 17 and up denalis had a different tcm? Could that be the source to my issue? I’ve had 2 shops unable to get it tuned .( won’t start either after Trans install) should I just call this a loss and look for one specifically for a 16? Thanks!

 

 

TCM is external on the 8 speed truck applications.  It is a different part# from 2015-2016 to 2017-2018 so there very well may be some sort of wiring changes made in the transmission and the wiring is different in the wiring to and from the transmission and TCM.  

 

They have to do a Solenoid Valve Characterization Reprogramming which requires some ID numbers off the transmission and then do the Service Fast Learn Procedure.  The first procedure is in the TCM in GM SPS programming, but the TCM itself doesn't need to be programmed.  

 

So I'd say its a 50/50 chance.  If a dealer can do those two procedures with the existing TCM, it might work.  If not, you'd need a 15-16 8L90 instead of a 17-18.  

Edited January 23, 2023 by newdude

[Jessiebandz]

Hey man thanks for the input! Do you think if I get a 2018 ecm and tcm it would be able to get programmed? Thank you

[TriZZZl3]

@Jessiebandz what ever came about this?

 

I just purchased an 8L90 from a 2018 6.2L (model 8UJL) to go on a 2016 5.3L (model 6U3L). I’m starting to get worried that I’m going to be in the same situation. 

[Jacob Fehr]

Hey were you able to get the transmission to work on your truck?