I am wanting to flash 02020003 OS into a 2002 12200411 PCM with a 6.0, 4L80e calibration.
I have a V2 and the newest updates. When I try to full flash the 02020003 OS into the PCM I get an error message of Tune File has an incorrect checksum.
I am not sure what to do next. I have looked through all of the tunes I have saved and I don't have any 2002 Gen3 truck COS3 tunes that I could use as a Full Flash starter tune. Any guidance would be welcome.

Jeff