Simple theft deterrent for electronic control modules

Abstract

An electronic theft deterrent system for deterring theft of an electronic device, such as a radio associated with a vehicle, that takes advantage of already existing device parameters, controls and displays associated with the device. When used as a theft deterrent system for the vehicle radio, a radio operator will first activate a frequency control switch in order to set an arbitrary frequency in the display of the radio. Next, a predetermined set of theft key radio control buttons are activated for a predetermined time in order to cause the arbitrary frequency that is displayed to be stored in a non-volatile memory. When the frequency is stored, the radio volume is impaired, but the total operation of the radio is not disabled. When the operator wishes to restore the radio to its normal operating condition, the operator will reset the arbitrary frequency, and reactivate the theft key control buttons. If the currently displayed frequency setting matches the stored frequency setting in the memory, the radio will be removed from the theft guarded condition, and the audio portion of the radio will be restored. If successive attempts to restore the radio to its normal operating conditions fail, an attempts counter will cause the radio to remain in its impaired state until an authorized service agent is able to restore the operation of the radio.