Some W-Body vehicles may be equipped with audio systems that have a Theft Deterrent Feature. The radio has this feature if it shows THEFTLOCK® on its face. THEFTLOCK® is designed to discourage theft of the radio. It works by using a secret code to disable all radio functions whenever battery power is removed (as when a battery cable is disconnected). If THEFTLOCK® is active, the THEFTLOCK® indicator will flash when the ignition switch is in the OFF position. The THEFTLOCK® feature for the radio may be used or ignored. If ignored, the system plays normally and the radio is not protected by this feature. If THEFTLOCK® is activated, the radio will not operate if stolen. When THEFTLOCK® is activated, the radio will display "LOC" to indicate a locked condition anytime battery power is removed. If the battery loses power for any reason, you must unlock the radio with the secret code before it will operate.
If the vehicle is equipped with a THEFTLOCK® radio and the radio is locked up but the codes have been lost or are unobtainable (change of vehicle ownership, etc.) the Dealer Communications System and Technical Assistance service available at the dealership can be consulted in obtaining a Factory Backup Code.