[MikeOD]

The pcm uses flash based memory. Your custom tune replaced the gm tune in the flash. It can never wind up reverting to anything other than what was flashed into it.

 

[MikeOD]

On a read failure, the pcm can be "reset" in this manner. On a flash failure, you have yourself an new doorstop, unless you get lucky. Sounds like you did!. Be forewarned. I have a stack of doorstops...........


Chris

And even then, when resetting from a read failure...it will only revert back to the last program flashed into it.

The "factory settings" referred to, just means it will not remember any trouble codes it had stored, it will not remember any fuel trim data it had stored, and whatever was causing it to not power up will be cleared as well...but if it HAD a non-stock program in, and you are subsequently recovering from a read error...you will still have a non-stock program in it.