Diagram shows the belt routing. Loosen the lock bolt and turn the adjuster to release the tension of the belt for removal. After belt removal, remove the pulley and check its bearing. Most probably that is the one that is bad and won't cost you much to have it replaced.
If I am not wrong, parts outlets such as autozone provides free scanning services but your model is pre-OBD-II so you can manually retrieve the codes. If the Check Engine Light is not showing, most probably you won't find any codes.
Wednesday, March 6th, 2013 AT 12:53 PM