i'd like to clear the codes on my 98 blazer but, i'm not sure how. i've heard of pulling the positive side battery terminal for 30 seconds but, that didn't seem to work. anyone know how i can do this?

 

Take it to Auto Zone and have the codes read, then ask them to clear the codes.
The guy won't be able to clear them himself, but he'll tell you what buttons to push to clear them yourself.

 

The short of it is that if you disconnect your battery for 10-15 minutes, the codes will clear. However, the codes will go away on their own provided that the problem has actually been repaired. If you haven't repaired the problem, there is no use in clearing the codes.

As an aside, clearing the codes will also reset all of your emissions monitors. If you are hoping to get through an inspection with a problem with your truck that comes and goes, you still may not pass the inspection if you do not get all (or most) of the monitors to the ready state by going through a few drive cycles.. And a few drive cycles might just be enough to have the code pop back up if left un-repaired.