Trying to change vin on E80 ECU. Having issues

[1gcrazy]

I connect an E80 ecu and change the vin with 7.5 Scan tool. If I do not clear codes before writing, I get error out of range. If I do clear codes before writing it will act as if it's going to write but then the vin will be the same original after turning the unit off for 15 seconds.
Any help here?

[GMPX]

The Clear DTC before changing VIN is a requirement on the E80 (well, on many late model GM ECM's).

Are you doing it in a car or on a bench harness?
If you are doing it on a bench harness it must be wired up so that when the Ignition 12V is turned off the Battery 12V remains, it is during that shutdown period the ECM will actually writes the VIN.