I'm not an expert either and correct me if I'm wrong but GM is not the only one uses OBD-II. ALL cars made after Jan 96 and sold in the USA are OBD-II compliant. different manufacturers use different protocols. Thats why there are manufacturer specific readers out there. GM uses VPW. Most 96-97 Toyota also use VPW. Fords use PWM. Chrysler and most imports use ISO9141 protocol. Most 98 Toyota switch to ISO9141. You can find which protocol your car uses at
Originally posted by mxxxxxm
I'm not an expert, but I have been trying to learn more about obdi2 for some time now.
I know GM uses obdi2 and you can use any obdi2 reader as long as it has the appropriate connector. [different manufacturers use diff connectors, but many share the same one with the same pin outs]
I also know that GM has an "enhanced" obdi2, meaning in order to use the enhanced information, you need a obdi2 reader that is compatible with the enhanced info stream.
hope that clears up some, I'm still trying to find a GM enhanced reader that isnt $400.