2011 Chevrolet Silverado 1500 Regular Cab Owner's Manual - Page 53

Keys, Doors and Windows 2-9 Doors Rear Doors (Extended Cab) The rear access door must be closed before the front door can close. Open the rear doors to access the security locks on the inside edge of each door. To set the locks, insert a key into the slot and turn it to the horizontal position. The door can only be opened from the outside with the door unlocked. To return the door to normal operation, turn the slot to the vertical position. To open a rear access door from the inside, first open the front door. Then, use the handle located on the inside of the rear access door to open. To open a rear access door from the outside, first open the front door. Then, use the handle located on the front edge of the rear access door to open it.