2014 L83 to 2020 l86 swap

[Sierraman92]

I’m  trying to swap my L83 and 6l80 in a 2014 sierra for a 2020 l86 and 10 speed trans. I don’t have the 2020 l86 harness or ecm, but I have everything else. If I get the harness and ecm for the 2020 will everything else be plug in play or what else will I need to do? No one seems to to have done this and I can’t find anyone who’s help. Thanks in advance. 

[newdude]

3 hours ago, Sierraman92 said:

I’m  trying to swap my L83 and 6l80 in a 2014 sierra for a 2020 l86 and 10 speed trans. I don’t have the 2020 l86 harness or ecm, but I have everything else. If I get the harness and ecm for the 2020 will everything else be plug in play or what else will I need to do? No one seems to to have done this and I can’t find anyone who’s help. Thanks in advance. 

 

 

Is the 2020 L86/10 speed out of a 2020 Tahoe/Yukon/Escalade?  So the 2015-2020 generation of SUV, K2XX.  

[Sierraman92]

No it’s out of a 2020 Sierra

[CamGTP]

Won't be plug and play with a E90 computer.

Your truck runs a E92 and all the CAN network stuff is based will that computer. Even running a newer computer from those 2020 Tahoe/Yukons that are still E92 presents it's own problems. Different type of vehicle, many revisions in tech from a 2014 so the likelyhood of any of the dash, abs and stuff like that working is very slim.

[Sierraman92]

Yeah I’m fearing the worst. It’s actually a L87 out of a 2020 Sierra. I didn’t know if Powertrain Swap Solutions would have a fix.

[newdude]

On 1/6/2025 at 5:15 PM, Sierraman92 said:

No it’s out of a 2020 Sierra

 

 

Oh.  Not good.  The T1 stuff is all different (2019-2022LTD in your case).  Nothing will plug and play.  

 

I mean, even if it was out of a 18-20 Tahoe/Yukon/Escalade it's not great either.  All the 10 speeds have external TCMs, where the 6 speeds are internal TCM.  So you'd 99% likely need the entire engine harness/transmission harness assembly.  Then you'd have to properly set up power/ground for the TCM and (obviously) install said TCM. 

 

You'd have been much better off building the 6L80 and finding an L86 and then have it tuned with the factory ECM to run the L86 tuning (likely HP Tuners and have someone load in the base tune for an L86 and go from there) and sell what you've got.  

 

Could you use the L87?  Probably but you'd have to change some things around as there are differences between L86 and L87.  Front cover and water pump is all different between them, L86 is AFM (four cylinders deactivate) where L87 is DFM (all 8 cylinders are active lifters and can deactivate), etc.  

Edited January 8, 2025 by newdude

[Sierraman92]

Yeah at this point I guess I’m going to be looking to trade the l87 and 10 speed for a L86. But I’m going to be wanting to put a stage 2 cam and upgraded valve train in to go with the Supercharger and also pull the 6l80 and have it built. So that’s $1700 for the trans build and $3k for upgraded valve train(when I say upgraded I mean trunion rocker arms, push rods, gm performance lifters, ARP bolts/studs for heads, headers, valve covers, with mls gaskets). Ahhh what do I do??