There are several reported incidents of people with recent versions of EFI live flashing OS and Tune and losing cylinder #1 after chaning PCM's

I myself have seen this issue and am working on one i have taken a known working PCM and after flashing still didnt have Cylinder #1.

At this point I have to thing its either something thats changed in an update or something wrong in the flashing of the Operating system.

Ill link this for others to post up too.

Wiring has been tripple checked.
White Truck EGR- Codes Cleared.ctz

lots of details here.
http://forum.gmtruckcentral.com/show...ING-1-CYLINDER

Thanks for your time.