WTH checksum failed after flash on 2 pcms, now 2 dead pcms

[GMPX]

Both pcms went through the sequence and stopped at the exact same time after writing to the pcm

Ok, but at what point? The start, the end, the middle? I know initially you said a Cal Flash right at the end, is that the same on both PCM's?

[joeygc5]

As far as I know it was at the end of process through observation. The pcm was connected> validations run> old tune erased>new tune OS file written> then checksum failed message appeared. I have no screen shots nor further info. Because watching my laptop with the PCM's in the vehicle (while tuning), the process stopped with both PCM's after the tune file was written (status display) and then the checksum failed message appeared. Then I wasn't able to do anything, no communication, no vehicle start, no finish of the tune process after the checksum error.

The truck is running and driving fine, idk what tune was in it, but it looked like a basically stock tune from the PE tables and timing maps.

[GMPX]

On these PCM's there is really only two things that will stop them being recoverable.

1 - Failure of a Full Flash within the first 20 seconds or so.
2 - A faulty calibration that causes the PCM to do an endless reset (divide by zero error it's called, can happen with speedo calibrations).

Given your situation it seems like neither of the above should apply. If it got to the end and the checksum failed then the flash finalisation would not have occurred, in which case the PCM should be in what we called "dead poll". Meaning it just sits there and broadcasts a message saying "I'm here but not 100% functional", kind of like a tortoise tipped on its shell, it's alive and kicking but not much else.

With a PCM in this state hooked up to a bench harness you should see one of the orange LED's on the V2 flashing about twice a second, that is the poll from the PCM to say it is not functional 100% but it can be bought back to life. Do you see that happening?

[joeygc5]

On these PCM's there is really only two things that will stop them being recoverable.

1 - Failure of a Full Flash within the first 20 seconds or so.
2 - A faulty calibration that causes the PCM to do an endless reset (divide by zero error it's called, can happen with speedo calibrations).

Given your situation it seems like neither of the above should apply. If it got to the end and the checksum failed then the flash finalisation would not have occurred, in which case the PCM should be in what we called "dead poll". Meaning it just sits there and broadcasts a message saying "I'm here but not 100% functional", kind of like a tortoise tipped on its shell, it's alive and kicking but not much else.

With a PCM in this state hooked up to a bench harness you should see one of the orange LED's on the V2 flashing about twice a second, that is the poll from the PCM to say it is not functional 100% but it can be bought back to life. Do you see that happening?

Connecting each "bad" pcm has the right side LED'S flash once then nothing and V8 is unable to auto-detect. Connecting good pcm constant LED flashing and no need to auto-detect as the V8 instantly recognizes.

[GMPX]

Where are you located out of interest?

[joeygc5]

Kansas City area.