Hey All..
Can anyone tell me what security features ( if any) does the factory alarm posses. I know if you push the lock button it locks the doors.What else? does it have a motion/shock sensor? Or a starter interrupt?if you click the lock button while in the car you can manually unlock the doors and exit with out setting off the sirens.while seated in the truck (alarm on) I can start the truck with out setting off the alarm.I mean how's this thing work? I haven't found anything other than a keyless entry system.

EXTadic,

I am not sure if the system has changed but with the factory system on my 04 Avalanche; if you sit in the vehicle and push the button to turn on the alarm system, it must be disengaged before you do anything manually, even from inside the truck. If you turn on the alarm and manually unlock the doors to start the truck, the alarm will go off.

That is a good thing because the alarm has some effectiveness even when the windows are down. If they reach in and unlock the door, or climb in and start it, the alarm will go off.