2003 Chevrolet Express Van Owner's Manual - Page 93

Power Door Locks Last Door Closed Locking This feature protects the owner from having an unsecured side cargo door. If the side cargo door is open when the lock button is pressed on the door or the remote keyless entry transmitter, all doors will lock and then re-lock again after the cargo door is closed. If the cargo door is not closed within several minutes, the re-lock will not occur. Press the bottom side of the power door lock switch to lock all the doors at once. Press the top side of the power door lock switch to unlock all the doors at once. When a door is locked, the inside door handle will not work. 2-8