Question:
Cloning GM ACDelco E39 ECM I read internal flash with Xhorse Multi Prog on bench and got the password is it enough to just write that file to donor or do I need to read in boot?
Here is the clue.
If you are cloning v6 to v6 or L4 to L4, just read and write the flash. But if you clone v6 to l4 or l4 to v6, you have to boot it or write it full using SPS Techline Connect.
You might still have to use sps2 to program after cloning, e39a and e39 have a known code that pops up, sps2 programming solves it.