Vin number wont store in ecm 411 ecm 02 Corvette Camaro

anyone got this problem before?
I have tried to change the vin. it says na00000000000000 in the vin in efilive and techII
I even tried to upload a new file from gm, with new vin in techII. Still return vin na00000000000000 after full flash.

yes of course I have tried to change it with the scan tool, and in the pcm tool in tune.

Ecm takes the tune file fine, but not the vin. M I missing something here?

The ecm had a valid vin before, and I have the original os for it. But when I full flash it back it takes the tune, but not the vin..
The ecm has newer been modified in the chip. What I did was to upload a custom os for it, and then flash it with a correct parameters tune.
After that, no more vin for me :music_whistling_1:

Try changing the VIN using the V7 scantool.

I have tried that.
I just tried on another ecm, and I have the same problem. I full flashed another ecm that was loade with a truck os, and flased it with a corvette tune with the same os number.
it is keeping the truck vin.
I did try in the scantool, but it still keep the truck vin

Solved. Not possible to do this in a bench harness..
tried in the car and working.

You can do it on the bench but your bench harness needs to provide 12V to the battery input constantly, then when you turn the ignition switch off (as you would on the car) that is when the PCM will commit the new VIN to flash memory.

You need bench harness with "ignition" switch which you turn off after writing VIN and wait 15+ seconds before removing the rest of power from PCM, as GMPX said.

Thanx. I have fixed the bench harness now. The count+ was wired into ACC+ wire.
So thanx for all help guys