Alarm State Activation

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.

Perform the following steps in order to verify that the system activates the alarm state:

Open a window. Opening the window ensures that you will be able to open the door from the outside using the manual door lock knob.
Place the system in the armed state.
Reach through the window and unlock the door using the manual door lock knob.
Open the door.

The system enters the alarm state. The following actions occur for approximately 2 minutes:

The horns sound intermittently.
The exterior lamps flash.
After 2 minutes and all the doors closed, the system automatically returns back to the armed state.