How to use an OBD-ii Scan Tool on older GM vehicle?

As Brian alluded to in his comment, in most cases it will not work. You have to have a reader which will read OBD-I. Some readers, like the Innova 3140 will read both, and comes with all of the adapters to attach to the “older” vehicles.

Brian also stated about the change to OBD-II. In the US it was mandated to change over in ’96. Some manufactures changed it over in ’95 as they were ahead of the power curve. Other companies changed the ALDL (computer connector) over in ’95 to the OBD-II connector, but kept the OBD-I computer. If you want to screw up a mechanic, this is the way you do it!

Obviously, your Suburban is OBD-I. It will require the OBD-I. As an alternative, you can use computer software to attach your laptop to your ‘Burban. This is done through a cable which attaches through your USB connector. I am pretty sure Datamaster can read your truck, but not positive. I used it on my ’94 Camaro … Pretty sure it will work for all of the GM vehicles. Anyway, Datamaster, if it will work for you, can be setup in a visual way to show the output as gauges and such, with a lot of user configurability to make it look like you want. It works well, too.