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Here's the breakdown:

Tech2 = Standalone Scan Tool for GM vehicles ~1994-present EXCEPT for GM's Global Architecture (Global A) Vehicles. An annual software subscription is required to keep the Tech2 operating software up to date. A CANdi module is required to use the Tech2 with GMLAN (CAN) --equipped vehicles (some GM vehicles as early as MY 2004, all GM vehicles beginning with MY2008).

Tech2 + GM Tis2Web subscription = remote method (connect to car/truck, request programming info for desired controller from car/truck, disconnect from car/truck, connect to PC, download programming file from GM through PC to tool, disconnect from PC, connect to car/truck, load programming file into desired controller) and pass-through method (car, Tech2 and PC are all hard-wired together at the same time, Tech2 serves as pass-through interface between car and PC, programming process is initiated/controlled from the PC) GM controller programming on non-Global A vehicles.

Multiple Diagnostic Interface (MDI) = GM's hardware interface which connects the car/truck to a PC. The connection from the MDI to the PC can be via wireless internet, CAT5, or USB cable. More info here:

http://www.archivedsites.com/techlink/2007/06/multiple-diagnostic-interface-watch-for-it.html

MDI + GM Tis2Web subscription = pass-through method (car, MDI and PC are all connected together at the same time, MDI serves as pass-through interface between car and PC, programming process is initiated/controlled from PC) GM controller programming only, for any GM controller that is capable of being pass-through programmed. Note that, unlike the Tech2, the MDI is not capable of remote method programming. There are some GM controllers that can only be programmed via the remote method. Note also that a capable scan tool is often required to perform post-programming controller setup or initialization functions.

Global Diagnostic System 2 (GDS2) = PC-based, subscription-based scan tool software used only with GM's Global A vehicles. This uses the MDI as the hardware interface to the vehicle. More info here:

http://www.archivedsites.com/techlink/2011/01/gds-2-is-here.html

Tech2Win = PC-based, subscription-based emulator software which allows Tech2 scan tool software to run on a PC. This uses the MDI as the hardware interface to the vehicle, and is used for non-Global A vehicles. It has some limitations compared to the Tech2, which are noted here:

http://members.iatn.net/forums/read/msg.aspx?f=forum8&m=128827&fv=3&page=1

The two most recent Tech2Win releases have been working well for me -- they don't seem as prone to lockups as some of the earlier versions. More on Tech2Win here:

http://www.archivedsites.com/techlink/2011/05/tech2win-application-puts-the-tech-2-on-your-computer.html

http://www.archivedsites.com/techlink/2011/06/installing-the-tech2win-application.html

Software subscription options/prices for all of the above and a list of GM's Global A vehicles (through MY2012) can be found here:

https://www.acdelcotds.com/acdelco/action/subscribehome

Michael Joachim
Owner
Mike Joachim
Pelham, Alabama, USA