Actron scan tool - how to obtain OBDII codes '95 T100

Two days ago, I attempted to use an Actron scan tool to read OBDII codes - nothing's wrong, I was just curious to see if everyting was within range. It was a loaner tool from my local Advance Auto Parts. I don't recall the model number. I plugged it in and followed the on-screen instructions. I was given the choice of Ford, GM, or something called "Global". I assume global means everything imported. So, I selected global. The upon actuating the scan function, the display acted like it was trying to communicate with the truck, but after a few seconds it showed some sort of a communications error. I tried everything again, same result. Now for the questions. Was I doing everthing right? Is there a trick to using a generic scan tool to get Toyota codes? I'm certain the system is OBDII. The check engine light is not on. Will any codes be set and not turn on the light? As I said, I'm just curious as to how things are running. When the truck starts rolling up this many miles, I can't help but think that things like the O2 sensors and such could start going south.