quick question on the segment swaps. Do you need to do all the same wiring ( changing the pins at the PCM mostly)
Everything in the photo below??

 

You put the brown wire in the u slot on the trans plug no need to change the pcm side of the brown wire. The white and tan/white wire will be re purposed for the new speed sensor and those will be pinned on 22 and 23 in the red pcm connector

 

Ok that's what I had thought. After figuring out that I had the new speed sensor in the wrong spot I rewired it the correct way and now the Trans is stuck in 2nd gear while going forward 😡

 

Check for pinched works or your 1-2 shift solenoid.

 

Commanding the solenoids on and off I can hear them working in the trans

 

Assuming this is not on an NNBS?

 

No trucks a 2001

 

I did a 2002 Yukon 80e swap like you're doing. Find my thread.

That said I had a bad valve body that kept me in 2nd gear.

Have you done pressure tests?

 

Also be sure to pull codes often. Some will put your trans in limp mode in short order. Once again, my dumbass knows first hand.