GMC Sierra Limited 1500 2019 Owner's Manual page 317

316 Driving and Operating
Electric Brake Control Wiring
Provisions
If the vehicle is not equipped with
an integrated trailer brake controller,
a trailer brake controller needs to be
installed on the vehicle if the trailer
has electric brakes. The brake
controller should be installed by
your dealer or a qualified service
center. If equipped, wiring
provisions for an aftermarket electric
trailer brake controller are included
with the vehicle as part of the trailer
wiring package. The harness
contains the following circuits:
Electric Trailer
Blue
Brakes
Red/Black or
Battery Feed
Red/Blue
Brake Apply
White/Blue
Signal
Ground Black
Refer to the aftermarket electric
trailer brake controller owner's
manual to determine wire color
coding of the electric trailer brake
controller. The wire colors on the
brake controller may be different
from the vehicle. The fuse for the
electric trailer brake circuit is in the
engine compartment fuse block, but
the wires may not be connected.
They should be connected by your
dealer or a qualified service center.
Trailer Lamps
Always check all trailer lamps are
working at the beginning of each
trip, and periodically on longer trips.
Turn Signals When Towing a
Trailer
When properly connected, the trailer
turn signals should will illuminate to
indicate the vehicle is turning,
changing lanes, or stopping. When
towing a trailer, the arrows on the
instrument cluster will illuminate
even if the trailer is not properly
connected or the bulbs are
burned out.
Tow/Haul Mode
For instructions on how to enter
Tow/Haul mode, see Tow/Haul
Mode 0 266.
Tow/Haul assists when pulling a
heavy trailer or a large or
heavy load.
Tow/Haul Mode is designed to be
most effective when the vehicle and
trailer combined weight is at least
75% of the vehicle's Gross
Combined Weight Rating (GCWR).
See Weight of the Trailer under
Trailer Towing 0 303.
Tow/Haul Mode is most useful when
towing a heavy trailer or carrying a
large or heavy load:
through rolling terrain.
in stop-and-go traffic.
in busy parking lots.
Operating the vehicle in Tow/Haul
Mode when lightly loaded or not
towing will not cause damage;
however, it is not recommended and
may result in unpleasant engine and
transmission driving characteristics
and reduced fuel economy.