1993 5.3 swap vcm scanner disconnecting

I have recently been tuning on a 1993 c1500 with a 2002 5.3 swap. It has a stand a lone harness from PSI. I can edit files and pull dtcs while the truck is in the RUN position but as soon as i crank the truck it kicks off the vcm scanner. I have tried running my harness ground straight the the battery, running straight power from battery to my OBD2 port. Battery is fully charged. I can start scanner with the key only in the run position but as soon as it cranks it turns it off. I do not know what else to try. I have also connected this laptop to another car with same cord and could tune on it just fine. All drivers are the newest 2.24 and i tried the last beta version and it was the exact same. HELP!!