Alarmed State
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2003 GMC Yukon XL, 2003 GMC Yukon, 2003 Chevrolet Tahoe, 2003 Chevrolet Suburban, and 2003 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
The CTD system will enter the alarmed state from the armed state if any door opens. The horns and the exterior lights will alternate off and on for approximately two minutes or until an unlock command is received by the BCM. If the BCM does not receive an unlock command, the CTD system will go back to the armed state. The BCM will request the security telltale to remain off. The CTD system will change from the alarm state to the off state if the vehicle control module (VCM)/powertrain control module (PCM) receives a valid Passlock™ ignition key rotation.