GMC Yukon 2021 Owner's Manual page 296

10 seconds. This message can be
acknowledged before it automatically
turns off.
CHECK TRAILER WIRING: This message will
display if:
The ITBC system first determines
connection to a trailer with electric brakes
and then the trailer harness becomes
disconnected the vehicle.
If the disconnect occurs while the vehicle
is stationary, this message will
automatically turn off in about
30 seconds. This message will also turn
off if it is acknowledged or if the trailer
harness is reconnected.
If the disconnect occurs while the vehicle
is moving, this message will continue
until the ignition is turned off. This
message will also turn off if it is
acknowledged or if the trailer harness is
reconnected.
There is an electrical fault in the wiring to
the trailer brakes. This message will
continue as long as there is an electrical
fault in the trailer wiring. This message
will also turn off if it is acknowledged.
To determine whether the electrical fault is
on the vehicle side or trailer side of the
trailer wiring harness connection:
1. Disconnect the trailer wiring harness
from the vehicle.
2. Turn the ignition off.
3. Wait 10 seconds, then turn the ignition
back to RUN.
4. If the CHECK TRAILER WIRING message
reappears, the electrical fault is on the
vehicle side.
If the CHECK TRAILER WIRING message
only reappears when connecting the
trailer wiring harness to the vehicle, the
electrical fault is on the trailer side.
SERVICE TRAILER BRAKE SYSTEM: This
message will display when there is a
problem with the ITBC system. If this
message continues over multiple ignition
cycles, there is a problem with the ITBC
system. Have the vehicle serviced.
If either the CHECK TRAILER WIRING or
SERVICE TRAILER BRAKE SYSTEM message
displays while driving, the ITBC system may
not be fully functional or may not function
at all. When traffic conditions allow,
carefully pull the vehicle over to the side of
the road and turn the ignition off. Check the
Driving and Operating
wiring connection to the trailer and turn the
ignition back on. If either of these messages
continues, either the vehicle or trailer needs
service.
A GM dealer may be able to diagnose and
repair problems with the trailer. However,
any diagnosis and repair of the trailer is not
covered under the vehicle warranty. Contact
your trailer dealer for assistance with trailer
repairs and trailer warranty information.
Trailer Sway Control (TSC)
Vehicles with StabiliTrak have a Trailer Sway
Control (TSC) feature. Trailer sway is
unintended side-to-side motion of a trailer
while towing. If the vehicle is towing a
trailer and the TSC detects that sway is
increasing, the vehicle brakes are selectively
applied at each wheel, to help reduce
excessive trailer sway. If equipped with the
Integrated Trailer Brake Control (ITBC)
system, and the trailer has an electric brake
system, StabiliTrak may also apply the
trailer brakes.
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