One problem related to door has been reported for the 2000 GMC Sierra. The most recently reported issues are listed below.
Consumer states the automatic lock is plainly visible whereas the manual lock is not, making the automatic lock the thiefs first choice and again the system in unarmed. When leaving the driver side or passenger window slightly open, intentionally or not, the location of the automatic door locks (facing upward on the armest), is such that a coat hanger bent through the opening can easily depress the automatic door lock, thereby disarming the vehicle making it possible to open the door from the outside without sounding the alarm to steal the contents.