Circuit/System Description
WARNING: This page is about a different car, the 2011 GMC Canyon and 2011 Chevrolet Colorado. However, it is still accessible from the selected car via links, so may be relevant.
To deter theft, the radio learns and stores the vehicle VIN. If the radio is removed from the vehicle and installed into another vehicle, the radio performs a VIN check. If the VIN stored in the radio and the VIN being reported over serial data do not match or no VIN is received, the radio will go into a theft lock state and be inoperative. The radio will also display LOC, LOCKED, or CODE.