2011 GMC Savana 3500 Passenger Owner's Manual - Page 173

Infotainment System 7-3 Theft-Deterrent Feature TheftLock is designed to discourage theft of the radio. The feature works automatically by learning a portion of the Vehicle Identification Number (VIN). If the radio is moved to a different vehicle, it does not operate and either LOC or LOCKED displays. When the radio and vehicle are turned off, there may be a blinking red light to indicate TheftLock is armed. With TheftLock activated, the radio does not operate if stolen. ® Operation AM-FM Radio