GMC 2009 Yukon XL Owner's Manual page 162

The manufacturer is not responsible for any radio or TV
interference caused by unauthorized modifications to
this equipment. Such modifications could void the user's
authority to operate the equipment.
CAUTION:
{
SBZA is only a lane changing aid and does not
replace driver vision. SBZA does not detect:
•
Vehicles outside the side blind zones which
may be rapidly approaching.
•
Pedestrians, bicyclists, or animals.
Failure to use proper care when changing lanes
may result in damage to the vehicle, injury, or
death. Always check the outside and rearview
mirrors, glance over your shoulder, and use the
turn signal before changing lanes.
When the system detects a vehicle in the side blind
zone, amber SBZA displays light up in the side mirrors.
This indicates that it may be unsafe to change lanes.
Before making a lane change, always check the SBZA
display, check the outside and rearview mirrors, look
over your shoulder for vehicles and hazards, and
use the turn signal.
2-56
SBZA Detection Zones
The SBZA sensor covers a zone of approximately one
lane over from both sides of the vehicle, 11 ft. or
3.5 m. This zone starts at each side mirror and goes
back approximately 16 ft. (5.0 m). The height of the zone
is approximately between 1.5 ft. (0.5 m) and 6 ft. (2.0 m)
off the ground.
Use caution while changing lanes when towing a trailer,
as the SBZA detection zones do not change when a
trailer is towed.