You wouldn't get much out of the gmtd scan without an ECM, it might read DTCs though, if you want a cheap way to just read the fault codes you can use the paper clip method HERE
Stefan told me that it will only work on 94-95. 92-93 is a different baud rate as is the abs brakes. One of the reasons that I bought a tech1. I love the gmtdscan tech. Much easier to operate than the tech1 , just not as versitile.