Leaving Your Vehicle - GMC Sierra 3500HD 2001 Owner's Manual

There are several ways to lock and unlock your vehicle.
From the outside, use your key or the keyless entry
system, if your vehicle has this feature.
To unlock the door, slide the manual lock up.
2-6
To lock the door from the
inside, slide the manual lock
located on your door down.
Power Door Locks (If Equipped)

Leaving Your Vehicle

If you are leaving the vehicle, take your keys, open your
door and set the locks from inside. Then get out and
close the door.
Press the top of the power
door lock switch, marked
LOCK, on either door to
lock both doors at once.
Press the ribbed side of the
switch to unlock both doors
at once.