I have a Gmt800 pickup that works on J1850 VPW. About a year and a half ago my truck was stolen while I was at the junkyard. I got lucky and it was returned me to relatively unscathed a few days later but in the time it was gone I was so hurt and now have a bit of paranoia with my truck. I know one other person has been able to update from the crappy passlock system to the newer security of the newer trucks which uses a transponder key. I did go out and get all the parts I would need for the conversion and they all do fit, but I can't figure out how to interface the new VCIM into the older BCM. My attempts to contact the one person who did it before me will not respond to me so I'm trying to figure it out myself. I have plenty of dumps of bcm eeprom but I don't know how to interface with the mcu, i'm not even sure what it is. I also dont' know how to reverse engineer the flash. Open to all suggestings