How to choose GM Diagnosctic Scan Tool: GM Tech 2 or MDI or MDI 2? GDS1 or GDS2?

Here’s an info about the General Motors scan tools, including discussion of the Tech 2, MDI and current GDS 2. It looks like the trend is toward subscription services and frequent payment for updates.


GM TECH 2 handheld scan tool or MDI-2 GDS2 PC-based system?

From 1992 to 2009 and certain newer vehicles, GM vehicles use the Tech 2 handheld scan tool. It is the same scan tool as is used also for GM, Saab, Izusu, Suzuki and Saturn including the Saturn Astra (Opel import).


The Tech 2 scan tool simply uses different 32 MB software cards which are removable and switchable. It is a very versatile tool. Extra memory cards cost an average of $400 for the dealership sw or $22 around for a decent clone program, which allows us to expand our diagnostic capabilities really inexpensively. The Tech 2 is menu-driven and user-friendly.


The Tech 2 scan tool is also used for reflashing GM vehicles. It uses a serial adapter with a network cable to connect the tech 2 to your laptop.


NOTE: A serial adapter is used on the laptops 9 pin serial port. Do not try to connect the tech 2 directly to your laptop with just a network cable, because it won’t work. GM has certified a specific brand serial to usb adapter for use on all modern laptops without a serial port. We do stock this part, with the cost being $59.95 plus shipping.


In 2004, GM began phasing in to CAN system cars and a CAN adapter was built so the Tech 2 could access them. GM called it a CANDI (Controller Area Network Diagnostic Interface) module.


If you are interested in having full diagnostic capability on GM vehicles 2009 and older, this is it. No compromises, and no expensive required subscription every year just to use it for diagnostics. You can count on the reliability of your diagnostic information 99.9% of the time when using a genuine Tech 2.


BEWARE OF CHINESE COPIES. THEY ARE SOLD EVERYWHERE. EBAY, Amazon, EVERYWHERE AVERAGING $400-900.00. Some don’t work correctly all the time and when they break, you throw them away. Don’t get suckered into a fake Tech 2 with a great price. We hear from people all the time that unfortunately got taken.


In 2010, GM started phasing out the Tech 2 in favor of a laptop-based system called GDS2. Six vehicles in 2010 are not Tech 2 capable anymore, with more being added to the list as the years go on.


The six vehicles are:

Chevrolet Camaro

Chevrolet Volt gas/electric hybrid

Buick Lacrosse

Cadillac SRX SUV

GMC Terrain

Chevrolet Equinox

However, as of 2013, there are still GM vehicles that require a Tech 2 scan tool, especially the trucks.


GM MDI or MDI 2? GDS1 or GDS2?

In 2010, GM made a change in their vehicles, moving to a global platform to simplify marketing their vehicles all around the world. The communication systems changed, and the Tech 2 scan tool was no longer able to access them.


In preparation for this change, GM years later released a laptop-based Multiple Diagnostic Interface or MDI – the blue box.


Now it is superseded by the MDI 2. It was only used for reflashing, but the dealers loved it because it was twice as fast due to its USB connection to the laptop. (The Tech 2 is a serial connection system and slower to transfer data for reflashing.)


GM then introduced the GDS1 (Global Diagnostic System version 1) scan tool to run on a laptop. The new GDS2 is simply a newer and better version.


GDS2 requires renewing of the license to use it by visiting the TIS2Web site at least once a month (if you have a yearly subscription). TIS2Web is GM’s website to download the scan tool or reflash data to update a vehicle’s computer.


You download vehicle software to your laptop and then you run the vehicle choice or program to scan from your laptop with the MDI 2 as the interface between your laptop and the vehicle. You don’t HAVE to be online to use GDS2, only download the latest software license to use it by visiting TIS2Web monthly.


When you start GDS2, the bottom of the screen shows how many days left till an update is required. If expired, simply log in to TIS2Web before you work on a GDS2 vehicle, and renew your license then.


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