GMC Sierra 2010 Owner's Manual page 437

4. Adjust the Trailer Gain by using the gain
adjustment (+ / -) buttons on the Trailer Brake
Control Panel.
5. Drive the vehicle with the trailer attached on a level
road surface representative of the towing condition
and free of traffic at about 20 to 25 mph (32 to
40 km/h) and fully apply the Manual Trailer Brake
Apply lever.
Adjusting trailer gain at speeds lower than
20 to 25 mph (32 to 40 km/h) may result in an
incorrect gain setting.
6. Adjust the Trailer Gain to just below the point of
trailer wheel lock-up, indicated by trailer wheel
squeal or tire smoke when a trailer wheel locks.
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.
7. Re-adjust 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
In addition to displaying TRAILER GAIN and
TRAILER OUTPUT through the DIC, trailer connection
and ITBC system status is displayed in the DIC.
TRAILER CONNECTED
displayed when a trailer with electric brakes is first
connected to the vehicle. This message will
automatically turn off in about ten seconds. The driver
can also acknowledge this message before it
automatically turns off.
CHECK TRAILER WIRING
displayed if:
1. The ITBC system first determines connection
to a trailer with electric brakes and then the trailer
harness becomes disconnected from the vehicle.
If the disconnect occurs while the vehicle is
stationary, this message will automatically turn off
in about thirty seconds. This message will also turn
off if the driver acknowledges this message off or if
the trailer harness is re-connected.
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 the
driver acknowledges this message off or if the
trailer harness is re-connected.
2. There is an electrical fault in the wiring to the
electric 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 the driver
acknowledges this message off.
This message will be briefly
This message will be
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