Wasn't aware there was anything like that for these trucks. After a quick Google search it looks like it's for OBD2 systems, unless there's an adapter or something. I have the OBD1 scan tool, I got the all clear with it when I tested a few days ago.

 

Did you plug it into the ABS system or the powertrain system? The PCM isn't going to give you ABS codes.

 

since you bring up the concept, how many different systems would these trucks have that are separate and does SRS have one or does the flashing light corresponds to a code the only interface one can have

 

SRS has one, too. It has been too many years for me to come up with all of the systems that can have codes stored. Later model vehicles have everything accessible through the OBDII port. These trucks do not.