Hi first post here, I could use a little help.

I'm having trouble rewriting the VIN on a 99 F-Body LS1B ECM os 09360361. I'm currently able to write the new non GM VIN to the ECU using the bidirectional controls in Scan V7.5, and the updated VIN will remain stored after cycling the ignition. The problem is after I either remove constant battery power or read the calibration from the ECM it will revert back to its original F-Body VIN. If I leave constant power on and cycle the ignition I can reconnect to it and it will display the new VIN on the handheld or pass-thru. I cant seem to get the updated VIN to commit to hard memory. I even let the ECM sit with constant power/ignition off for awhile and still had the same results.

Some notes about my setup. ECM is powered on the bench through a harness and I'm using a V2 with the latest updates. I verified pins 20 and 57 on the blue connector have constant power and pin 19 has switched power. Pins 1 and 40 also have ground. My only concern is that I have it powered by a "dumb" battery charger that is most likely putting out some nasty DC. I can maintain a pretty steady 12.8v but I dont know how clean the power is. Has anybody run into an issue like this before? Thanks in advance!