Content Theft Deterrent (CTD) System
WARNING: This page is about a different car, the 2003 GMC Sonoma, 2003 GMC Jimmy, 2003 Chevrolet S10 Pickup, and 2003 Chevrolet Blazer. 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.