General Motors and Isuzu have had a long and odd kind of relationship where compact trucks are concerned. Originally, the General simply rebadged Isuzu Faster pickups as the Chevrolet LUV -- a move that nearly killed the concept of captive imports in the 1970s. Later, when GM released the award-winning S-10, GMC S-15, and their Blazer and Jimmy SUV derivatives, the tables had turned, and Isuzu began rebadging these jointly developed American trucks as their own.
After the 1996 model year, all vehicles sold in the United States came with the OBD-II programming protocol in use today. Prior to OBD-II, every automaker used a different computer system, programming language and diagnostic procedure, which meant that shops had to have a different scanner for every make of vehicle they serviced. Being a 1998, this Jimmy uses a now-standard programming protocol that can be read by any generic code scanner. You can also clear the codes very easily with the same scanner, which is the only method short of disconnecting the battery to do so.
If you're like most people, your surest access to a scanner will be your local chain auto parts store. Most have OBD-II code scanners for customer use. If you've never used a scanner before, have an employee go out with you and walk you through the code reading process. Note the trouble codes, and then ask about clearing them. Most likely, the employee will hand you the scanner, and have you push the button to clear them yourself. For legal and liability reasons, most stores prohibit employees from clearing customer trouble codes; they'll let you do it, and probably show you how if you're having trouble following the prompts on the scanner. But you'll have to push the button to clear them yourself.
If you can't get to a scanner, or the parts store gives you problems, you can clear them just as easily by disconnecting the battery for five minutes. The downside to this approach is that you'll lose all your radio presets, and force the computer to relearn the sensor data and self-adjust for them.
