A bad ignition switch will make it nearly impossible to start your GM vehicle. If you must remove the ignition switch, remember that the exact process can vary due to the large number of GM models. The switch works directly with the key lock cylinder; on most models you must remove this first.
Disconnecting the negative battery cable is always the first step when working with something electrical. On some models---often the trucks---you must loosen a screw or bolt to disconnect the cable. Remove the black cable and set it where it won't come into contact with the terminal.
You should also disable the driver's air bag system (if your vehicle is so equipped) as a precaution. With the wheels facing forward and the ignition switch in the "lock" position, remove the air bag fuse from the fuse box. Wait at least two minutes for the backup power supply to deplete. Now remove the driver's knee bolster so you can reach and disconnect the air bag connector. Leave the knee bolster open.
You must remove the trim covers to the steering column to reach the ignition switch and lock cylinder. Pull out the tilt lever, if one is installed, and remove the cover's screws. Insert the key and turn it to the "start" or "run" position. Now you need a retaining pin---a small, thin metal rod that looks like a lock pick. Push this retaining pin into the hole at the top of the ignition module, and pull the lock cylinder out with the key still inside it. The electrical portion of the switch remains installed. Disconnect all electrical connectors to the switch, then locate the two removal holes near the spot where the lock cylinder was. Insert a screwdriver into each of these holes together to remove the switch from the steering column.
Some Cadillac models are different. You can remove the switch without taking out the lock cylinder. Make sure it's in the "lock" position. With the trim panel under the steering column removed, pull out the bolts or nuts that connect the steering column bracket to the instrument panel, and lower the steering column. Now remove the wiring cover to the ignition switch by pulling out its screws. Remove the retaining screws for the switch, and disconnect its harness connector.
