2001 GMC Sierra 1500 Pickup Owner's Manual - Page 96

Rear Doors Your vehicle may be equipped with a rear access door(s) that allows easier access to the rear area of the extended cab. 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. To open a rear access door from the inside, the front door must be opened first. Then, use the handle located on the inside of the rear access door to open it. If your vehicle is a Crew Cab, you can open your doors from the inside or outside. Your vehicle may also have a feature which prevents children from opening rear doors. See "Child Security Locks" in the Index for more information. You must fully close a rear access door before you can close the front door. 2-13