GMC 2002 Yukon XL Owner's Manual page 283

Four Wire Trailer Harness Adapter
-
If you need to tow a light
-
four way round pin connector, an adapter connector is
included with your vehicle.
Power Winches
If you wish to use a power winch on your vehicle, only
use it when your vehicle is stationary or anchored.
4-72
duty trailer with a standard
Connect the adapter with
the tab (arrow) pointing
toward the top. The cap
on the wiring harness will
lock onto the tab (arrow)
and help hold the adapter
in place.
NOTICE:
Using a power winch with the transmission in
gear may damage the transmission. When
operating a power winch, always leave the
transmission in NEUTRAL (N).
Use the regular brakes, set the parking brake, or block
the wheels to keep your vehicle from rolling.
Step-Bumper Pad
Your vehicle has a rear step bumper, it is equipped with
a rear step pad at the center of the bumper.
If you will be using the
bumper to tow a trailer, you
must remove the center
cutout circle to install the
trailer ball.