Disconnect the negative battery cable. Remove the steering column trim covers. Remove the park lock cable from the bottom of the housingInsert the key into the ignition and rotate to the ACC position. Depress the locking button through hole on the side of ignition module assembly with a thin pick-type tool.
Important: Once the locking button is depressed, the tool must be removed before the cylinder wil slide out of the housing.
Slide the lock cylinder out of the ignition housing.
Make sure you clean the housing out with brake clean and a rag. After you clean it apply gm super lube to inside of housing and lock cylinder before putting it togther. Here is the part number #12371287 you can get this at the dealer. Very important that you lube it or you will have the same problem. Post back if this works.