GMC 2001 Sierra - Manual (Page 134)

2-51
Locking Rear Axle
If your vehicle has this feature, your locking rear axle
can give you additional traction on snow, mud, ice, sand
or gravel. It works like a standard axle most of the time,
but when one of the rear wheels has no traction and the
other does, this feature will allow the wheel with
traction to move the vehicle.
Horn
To sound the horn, press the center pad on the
steering wheel.
Tilt Wheel
The tilt steering wheel
allows you to adjust the
steering wheel before
you drive.
You can also raise it to the highest level to give your
legs more room when you enter and exit the vehicle.
To tilt the wheel, hold the steering wheel and pull the
lever. Move the steering wheel to a comfortable level,
then release the lever to lock the wheel in place.