Content Theft Deterrent (CTD) System
WARNING: This page is about a different car, the 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Silverado, and 2003 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The Content Theft Deterrent function provides the theft deterrent by sounding the horn and flashing the headlamps and the park lamps when there is an unauthorized vehicle entry or there is tampering detected.