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Discussion Starter #1
can leaving it unhooked from a car for long periords or anyone know anyway that a pcm would lose a custom tune??
 

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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.
 

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That's not to say that the PCM can still go bad.
 

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Discussion Starter #5
That's not to say that the PCM can still go bad.
just curious cause it has been sitting in my closet for a year during my rebuild and am putting it back together soon

thanks for the replies
 

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just curious cause it has been sitting in my closet for a year during my rebuild and am putting it back together soon

thanks for the replies
I think it can. I use LT1 Edit \ OBD2 Prog to load new programs to my PCM. A couple of years ago I was half way through loading when my laptop hung and I was left with a car that wouldn't start and the PCM would not respond to my laptop. I emailed Bryan Herter for help and he advised to disconnect the battery and leave it for I think it was 15 or 30 minutes and the PCM would revert to factory settings. This I did and was able to start the car and then load up the new programing.

George
 

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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
 

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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.
 

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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.
Thanks for the clarification. Now I don't have to panic every time I disconnect the battery.

George
 
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