The negative battery terminal cable needs to be unplugged. Take off the knee bolster and steering column covers. After that, track the wiring harness from the ignition switch down the column to disconnect the ignition switch electrical connector. The key should be inserted and continuity checked between indicated terminals of the connector at each position on the ignition switch. Replace if different from specified continuity. Also, verify that there is no wear or looseness in the ignition lock cylinder and that its key positions align with markings on housing. If the ignition lock cylinder is defective, the entire steering column lock assembly must be replaced. To replace, follow steps to access the ignition switch. The ignition lock cylinder cannot be replaced by itself: the whole housing must be replaced. Remove shear-head bolts retaining ignition switch/ignition lock cylinder assembly and separate bracket halves from the steering column. This can be done by drilling a hole in each bolt's center and removing them with screw extractors. Put new switch assembly into place, install shear-head bolts as well as tightening them until they snap at their heads. Finally, make sure you center the airbag clock spring when you are installing a steering wheel where it was removed.