Hi, Steve - - -
About three weeks ago was my first time for the annual smog check with no more testing equipment than plugging into the OBD-II socket. Of course, I had to query the smog-check folks about this development.
Allegedly, *all* makes and models from '96 onwards (at least as sold in the U.S.) do have full computer access via the OBD-II connector. The only problem is in decoding the "manufacturer specific" codes - which is being addressed by our "friends" in Washington even as we speak. This is one time that the interests of a special interest group (auto shops) are such that you and I may benefit, too. If Volvo continues their history of "cooperation" in this area, the codes will be available at $$$!!!
Interesting comparison, my son drives a '95 Subaru that my wife had for a time. I had bought the factory shop manuals for just over $US200 - three 2.5" binders' worth of general and specific information. When I checked out a code for him, the Subaru manual listed both the results obtained in using their proprietary test gear *and* the more common tabular listing.
bob noble Reno, NV, USA