I believe that was sarcasm.

I don't know why they think it is a problem. They are all the time claiming "bad computer", who programs them for them?

Don- 10-4 on the possible sarcasm...

‘Hello donbrew. I asked the Chevy guy who did my GMTU if he had to re-download my file.
He said he never got a flash file. Then went on to say GM did the tweaks on their end and when finished told him to load the VIN.
So im guessing any time I load the VIN I get the GMTU?

read below......

I had a Locksmith reprogram the ECM/TCM to stock with no problem. Took about an hour and half and it started when all done. .didn’t have time to drive it to see if the GMTU is in there. If not it will throw a bunch of codes?

‘Might get to it today

Hello again,
I wanted to see two things with the swap today.

1.) Was the Passlock seeding going to be triggered between the BCM and the new ECM?
......A.) No it hasn't....I can swap back and forth it makes no difference. Starts right away each time.

2.) Was my GMTU tagged in with my VIN?
......A.) YES...the new ECM will Boost 20-25 PSI just as the old one. No codes or lights

So Im very happy it played out like I wanted it with no trade offs.
Now I can start some custom tunes.

Cheers!

PK3 is NOT the old fashioned Passcode BS. Just a transponder and TDM that tells the BCM go no go. There is a challenge/response between the transponder in the key and the TDM on the cylinder..

None of those scary stories you have heard apply.

I have purchased a pre programmed to my VIN ECM that came with irrelevant directions to re program the ECM. All it actually needed was the crankshaft sensor calibration; if you are luck you got no code for that, but... it still needs to be done. The code you usually get is for there being NO data, there is no code for incorrect data (left over from the previous motor).
P0315 CKP not learned (no data)
P0335 CKP circuit
P0336 CKP performance

From Mitchell OnDemand:
https://cimg1.ibsrv.net/gimg/www.che...ba8aa616f1.png