The Tech II will not work on some 2009 GM vehicles. The MDI is replacing the Tech II. The MDI works with a Laptop. It is just a linking device between the vehicle and the Laptop. The MDI is a wired or wireless device. I can place the MDI in a vehicle in the parking lot and communicate with with it on my PC.
When GM told us about this device they said that it would be released as a Diagnostic and Programming device.
They released some information about a year later telling us that they were having problems with the Hardware for 1995 and prior OBD I vehicles. This was holding them up from releasing ALL Diagnostic Software. WFT who cares! Give me the OBD II stuff!
Rumor has it that we will be getting the Diagnostic Software Soon.