GMC 2011 Yukon XL Denali Owner's Manual page 331

See Weight of the Trailer in Trailer
Towing on page 9 67. Tow/Haul is
most useful under the following
driving conditions:
When pulling a heavy trailer or a
large or heavy load through
rolling terrain.
When pulling a heavy trailer or a
large or heavy load in stop and
go traffic.
When pulling a heavy trailer or a
large or heavy load in busy
parking lots where improved low
speed control of the vehicle is
desired.
Operating the vehicle in Tow/Haul
when lightly loaded or with no
trailer at all will not cause damage.
However, there is no benefit to the
selection of Tow/Haul when the
vehicle is unloaded. Such a
selection when unloaded may
result in unpleasant engine and
transmission driving characteristics
and reduced fuel economy.
Tow/Haul is recommended only
when pulling a heavy trailer or a
large or heavy load.
Integrated Trailer Brake
Control System
The vehicle may have an Integrated
Trailer Brake Control (ITBC) system
for electric trailer brakes.
This symbol is located on the Trailer
Brake Control Panel on vehicles
with an Integrated Trailer Brake
Control System. The power output
to the trailer brakes is based on the
amount of brake pressure being
applied by the vehicle s brake
system. This available power output
to the trailer brakes can be adjusted
to a wide range of trailering
situations.
Driving and Operating
The ITBC system is integrated
with the vehicle s brake, anti lock
brake and StabiliTrak systems.
In trailering conditions that cause
the vehicle s anti lock brake or
StabiliTrak systems to activate,
power sent to the trailer's brakes
will be automatically adjusted to
minimize trailer wheel lock-up.
This does not imply that the trailer
has the StabiliTrak system.
If the vehicle s brake, anti lock
brake or StabiliTrak systems are
not functioning properly, the ITBC
system may not be fully functional
or may not function at all. Make
sure all of these systems are
fully operational to ensure full
functionality of the ITBC system.
The ITBC system is powered
through the vehicle's electrical
system. Turning the ignition off will
also turn off the ITBC system. The
ITBC system is fully functional only
when the ignition is in ON or
in RUN.
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