A variety of manufacturers make the scan tools, my brother has a Snap-On. The tricky part is the software. The Hummer has it's own card for the tools. It is apparently close to a GM motorhome program but not quite the same.

My '96 tech manual describes the PCM/TECH 1 SCAN TOOL as follows (the diagnostic procedures in the manual assume the use of a tech 1 produced by Vetronix is able to perform functions such as bidirectional communications):

We (AMG) recommend the tech 1 be used whenever possible----the PCM can communicate a variety of information through the data link connector. This data is transmitted at high frequency and requires a scan tool.

AMG identifies all HUMMER power plants using the FOURTH digit of the VIN code. GENERAL MOTORS uses the EIGHTH digit of the VIN code. When the tech 1 scan tool asks for the EIGHTH digit of the VIN, LOOK AT THE FOURTH DIGIT OF THE VIN AND TRANSLATE TO THE GM CODE:

(See Deciphering the VIN)

When the tech used the tech 1 it verified the engine as a 6.5 TD. He then proceeded to scroll through the fault codes and the description of the codes. Did not have to go to the tech manual. I was impressed. Based on what I saw I believe it is a GM software. Maybe the "Diesel Page" has more. on this subject.

George

I just bought an EZ-Link scan tool from Summit racing. I bought the full package because I have a variety of vehicles, but, they do sell manufacturer specific packages. They are about $170, the one I got is $400. The more expensive one will scan just about any vehicle out there that is OBD-1 or 2 compliant. Along with other communication protocols. EZ-link is interested to see if their scanner works on a Hummer. The one piece of info that is necessary is the 8th VIN letter which tells the engine size of the vehicle(or 4th on the Hummer, but it must be matched to the 8th VIN letter on a GM, which was posted by George). The tool is very simple to use. I've already used it on a '97 Ford Expedition with no problem. I'll try the Hummer this weekend.

Bill Myer