GMC Yukon XL Denali Owner's Manual page 309

Electric Brake Control Wiring
Provisions
These wiring provisions are
included with the vehicle as part of
the trailer wiring package. These
provisions are for an electric brake
controller. The instrument panel
contains blunt cut wires near the
data link connector for the trailer
brake controller. The harness
contains the following wires:
Dark Blue: Brake Signal to
Trailer Connector
Red/Black: Battery
Light Blue/White: Brake Switch
White: Ground
It should be installed by your dealer
or a qualified service center.
If the vehicle is equipped with an
ITBC, the blunt cuts exist, but are
not connected further in the
harness. If an aftermarket trailer
brake controller is installed, the
ITBC must be disconnected.
Do not power both ITBC and
aftermarket controllers to control the
trailer brakes at the same time.
Tow/Haul Mode
Pressing this button at the end of
the shift lever turns on and off the
tow/haul mode.
This indicator light on the instrument
panel cluster comes on when the
tow/haul mode is on.
Driving and Operating
Tow/Haul is a feature that assists
when pulling a heavy trailer or a
large or heavy load. See Tow/Haul
Mode on page 9 31 for more
information.
Tow/Haul is designed to be most
effective when the vehicle and
trailer combined weight is at least
75 percent of the vehicle's Gross
Combined Weight Rating (GCWR).
See Weight of the Trailer in Trailer
Towing on page 9 59. 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.
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