The 1997 Pontiac Bonneville is one model car in which the ignition switch is actually built into the steering column's lock cylinder. Replacing an ignition switch in this case means replacing the cylinder as well. This is still not a very easy procedure, however, as you need to disconnect the steering wheel in order to remove the lock cylinder from the steering column. Take special care to ensure nothing goes out of alignment during this procedure.
Disconnect the car's negative battery cable. If your Bonneville is equipped with air bags, disconnect the positive cable afterward, then wait 2 minutes. Skip to Step 3 if there are no air bags.
Twist a flat screwdriver clockwise in each of the two openings in the back of the steering wheel until the air bag module pops loose. Lift the module up and off the steering wheel, then press the electrical connector's clip to disconnect it.
Grasp and remove the steering wheel nut's retainer in the center using locking pliers, then remove the nut with a wrench and deep socket.
Mark the wheel's relationship to the steering shaft, marking a line down the top end of the wheel and shaft with a dark marker.
Turn the steering wheel's center bolt with a steering wheel puller clockwise to tighten the bolt until it pops the wheel loose and free, then remove the puller from the wheel. Disconnect the horn's and other electrical connectors by pressing their tabs, then remove the wheel.
Remove the steering column trim covers by unscrewing the two screws from the lower column with a Phillips screwdriver, and separating the two column halves by hand.
Insert the key in the lock cylinder and turn it to the Start position. Insert a size 3/16 Allen wrench into the small hole in the top of the lock cylinder casing; the cylinder's release pin is in that hole.
Turn the key to the Run position while pressing down on the release pin with the Allen wrench, and pull the lock cylinder/switch out.
Insert the key for the new lock cylinder in the cylinder, then slide the cylinder and ignition switch into the hole. Be sure the key is lined up with the "Run" position that is marked on the cylinder casing.
Reconnect the steering column covers to the column, pushing them together on the column so their clips engage, then screw the lower column in place with its screws and your screwdriver.
Slide and push the steering wheel onto the steering shaft, using your tape/paint marks to properly align the shaft and wheel. Install and tighten the steering wheel nut as tightly as possible; tighten it to 30 foot-lbs. if you have a torque wrench.
Connect the electrical connector for the air bag, horn and other components using their quick-connect fittings you disconnected previously. Gently slide the air bag module onto the steering wheel; the retaining pins should engage and lock the module in place.
Reconnect the car battery, starting with the positive cable before the negative one if you had completely disconnected the battery.
