2004 GMC Envoy Owner's Manual - Page 75

Power Door Locks The power door lock switches are located on the driver's and front passenger's armrests. You can lock or unlock the door from the inside by sliding the manual lever forward or rearward. When the door is unlocked, you can see a red area on the lever. The manual lever on each door works only that door's lock. Remove the ignition key and press the lock symbol to lock all of the doors at once. To unlock the doors, press the other side of the switch. 2-9