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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 puffs of 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 you notice trailer wheel
lock-up at any time while you are 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 – This message will be
brie y displayed when a trailer with electric brakes
is rst 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 – This message will be
displayed if:
1. The ITBC system rst 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.
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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.
To determine if the electrical fault is on the vehicle
side or trailer side of the trailer wiring harness
connection, do the following:
1. Disconnect the trailer wiring harness from the
vehicle.
2. Turn the ignition OFF.
3. Wait ten seconds, then turn the ignition back
to RUN.
4. If the CHECK TRAILER WIRING message
re-appears, the electrical fault is on the
vehicle side.
If the CHECK TRAILER WIRING message
only re-appears when you connect the trailer
wiring harness to the vehicle, the electrical
fault is on the trailer side.SERVICE TRAILER BRAKE SYSTEM – This
message will be displayed when there is a problem
with the ITBC system. If this message persists over
multiple ignition cycles there is problem with the
ITBC system. Take your vehicle to an authorized
GM dealer to have the ITBC system diagnosed and
repaired.
If either the CHECK TRAILER WIRING or
SERVICE TRAILER BRAKE SYSTEM message is
displayed while you are driving your vehicle, you no
longer have power available to your trailer brakes.
When traffic conditions allow, carefully pull your
vehicle over to the side of the road and turn the
ignition off. Check the wiring connection to the
trailer and turn the ignition back on. If either of these
messages continues, either your vehicle or your
trailer needs service.
An authorized GM dealer may be able to diagnose
and repair problems with your trailer. However, any
diagnosis and repair of your trailer is not covered
under your GM Warranty. Please contact your
trailer dealer for assistance with trailer repairs and
trailer warranty information.
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When replacing the fuel cap, turn it clockwise until
it clicks. It will require more effort to turn the
fuel cap on the last turn as you tighten it. Make
sure the cap is fully installed. The diagnostic
system can determine if the fuel cap has been left
off or improperly installed. This would allow fuel
to evaporate into the atmosphere. SeeMalfunction
Indicator Lamp on page 262.
The TIGHTEN GAS CAP message will be
displayed on the Driver Information Center (DIC) if
the fuel cap is not properly installed. SeeDIC
Warnings and Messages on page 281for more
information.
{CAUTION:
If a re starts while you are refueling, do
not remove the nozzle. Shut off the ow of
fuel by shutting off the pump or by
notifying the station attendant. Leave the
area immediately.Notice:If you need a new fuel cap, be sure to
get the right type. Your dealer/retailer can
get one for you. If you get the wrong type, it
may not t properly. This may cause your
malfunction indicator lamp to light and may
damage your fuel tank and emissions system.
SeeMalfunction Indicator Lamp on page 262.
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