From what I can tell, and since I only have the GM enhanced function out of all the availible enhanced manufacturer options, when scanning an OBD-II GM, the first initial scan happened and then asked if the vehicle had a manual transmission or automatic transmission. This appears to be different from the way they did OBD-1, but I have yet to scan an OBD-1 vehicle-GM in particular- to find out if the setups for OBD-II are the same as OBD-I.