[blazer94]

If your ALDL <Assembly Line Data Link> connector is under the dash, you can read your own codes from the SES (service Engine Soon Light) It is a easy trick to do.
A. Use a jumper or a paper clip to connect the two connectors on the top row from right to left.
B. Turn ignition to run, but do not start the engine

The SES light will flash code 12, which is one flash, pause, two quick flashes. It will do this 3 times, than it will flash any stored codes. When all stored codes are flashed, it will flash code 12 again to signal it is finished.A haynes manuel can tell you all this, and will also have a readout of what the codes indicate. After repair, to clear the codes, disconnect your ground cable from your battery. ( I always wait 10 min to be sure) this will also reset your idle speed, so when you have re-connected, start vehicle, put in D with foot on the brake and allow your vehicle to re-learn it's idle, especially if you have performed any changes/repairs.