GMC Yukon 2021 Owner's Manual page 295

294 Driving and Operating
the output to the trailer off, adjust the
Trailer Gain setting to 0.0. This setting can
be adjusted from 0.0 to 10.0 with a trailer
connected or disconnected.
TRAILER OUTPUT: This displays anytime a
trailer with electric brakes is connected.
Output to the trailer brakes is based on the
amount of vehicle braking present and
relative to the Trailer Gain setting. Output is
displayed from 0 to 100% for each gain
setting.
The Trailer Output will indicate - - - - - - on
the Trailer Brake Display Page whenever the
following occur:
No trailer is connected.
A trailer without electric brakes is
connected, no DIC message will display
A trailer with electric brakes has become
disconnected, a CHECK TRAILER WIRING
message displays on the DIC
There is a fault present in the wiring to
the trailer brakes, a CHECK TRAILER
WIRING message displays on the DIC
The ITBC system is not working due to a
fault, a SERVICE TRAILER BRAKE SYSTEM
message displays in the DIC
Manual Trailer Brake Apply Lever
Slide this lever left to apply the trailer s
electric brakes independent of the vehicle s
brakes. Use this lever to adjust Trailer Gain
to achieve the proper power output to the
trailer brakes. The trailer's and the vehicle's
brake lamps will come on when either
vehicle brakes or manual trailer brakes are
applied and properly connected.
Trailer Gain Adjustment Procedure
Trailer Gain should be set for a specific
trailering condition and it must be
readjusted anytime vehicle loading, trailer
loading, or road surface conditions change.
Warning
Trailer brakes that are over-gained or
under-gained may not stop the vehicle
and the trailer as intended and can result
in a crash. Always follow the instructions
to set the Trailer Gain for the proper
trailer stopping performance.
To adjust Trailer Gain for each towing
condition:
1. Drive the vehicle with the trailer
attached on a level road surface
representative of the towing condition
and free of traffic at about 32 to
40 km/h (20 to 25 mph) and fully apply
the Manual Trailer Brake apply lever.
Note
Adjusting Trailer Gain at speeds lower than
32 to 40 km/h (20 to 25 mph) may result in
an incorrect gain setting.
2. Adjust the Trailer Gain, using the Trailer
Gain adjustment buttons, to just below
the point of trailer wheel lock-up,
indicated by trailer wheel squeal or tire
smoke when a trailer wheel locks.
Note
Trailer wheel lock-up may not occur if
towing a heavily loaded trailer. In this case,
adjust the Trailer Gain to the highest
allowable setting for the towing condition.
3. Readjust Trailer Gain any time vehicle
loading, trailer loading, or road surface
conditions change or if trailer wheel
lock-up is noticed at any time while
towing.
Other ITBC-Related DIC Messages
TRAILER CONNECTED: This message will
briefly display when a trailer with electric
brakes is first connected to the vehicle. This
message will automatically turn off in about