Help !!! 6l90e won't shift out of 1st
 

I'm looking for a little help, I've just finished up a 2015 L20 6l90e swap in a 88 chevy truck. It starts runs and drive but it will not shift out of first, I'm using the matching engine,e38 pcm, and transmission out of the same van. Any info will be greatly appreciated !
Thanks !

Check main trans pigtail for fully plugged in.

I've checked the plug, it's not bringing up any codes and the Snap On scanner is showing the shift command up to 4th gear but never shifts out of 1st just revs out to rev limiter.

I know old thread
 

Did you ever find a fix for this issue?

Yes, I've actually had to deal with this a few times now, basically I've ended up with engines and transmissions ( 6l90's ) that were not out of the same ( original ) vehicles so the ECU and TCU (that is internal and part of the valve body on 6l90 and 6l80's ) did not have the same VIN's. So long story short I had to find someone that could "marry" the ECU and TCU then had to remove the TCU and ship the ECU out with TCU. When I got them back and everything hooked back up everything worked like it should.

the e38 and co. can be very sensitive to VIN/OS/MY mismatch