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 towingOther 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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To remove the fuel cap, turn it slowly
counterclockwise.
{CAUTION:
Fuel can spray out on you if you open the
fuel cap too quickly. If you spill fuel and
then something ignites it, you could be
badly burned. This spray can happen if
your tank is nearly full, and is more likely
in hot weather. Open the fuel cap slowly
and wait for any hiss noise to stop. Then
unscrew the cap all the way.
If your vehicle is a dual fuel tank chassis cab
model, and it runs out of fuel, refuel the front fuel
tank rst to ensure a quick restart.Be careful not to spill fuel. Do not top off or over ll
the tank and wait a few seconds after you have
nished pumping before removing the nozzle.
Clean fuel from painted surfaces as soon as
possible. SeeWashing Your Vehicle on page 601.
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 260.
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 279for more
information.
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Your dealer has GM-trained service people who
will perform this work using genuine GM parts and
reset the system. It is also important to check
your oil regularly and keep it at the proper level.
If the system is ever reset accidentally, you
must change your oil at 3,000 miles (5 000 km)
since your last oil change. Remember to reset the
oil life system whenever the oil is changed.
How to Reset the Engine Oil Life
System
The Engine Oil Life System calculates when to
change your engine oil and lter based on vehicle
use. Anytime your oil is changed, reset the
system so it can calculate when the next oil
change is required. If a situation occurs where you
change your oil prior to a CHANGE ENGINE
OIL SOON message coming on, reset the system.Always reset the engine oil life to 100% after
every oil change. It will not reset itself. To reset
the Engine Oil Life System, do the following:
1. Display the OIL LIFE REMAINING on the DIC.
If your vehicle does not have DIC buttons, the
vehicle must be in PARK (P) to access this
display. SeeDIC Operation and Displays (With
DIC Buttons) on page 268orDIC Operation
and Displays (Without DIC Buttons) on
page 275.
2. Press and hold the SET/RESET button on
the DIC, or the trip odometer reset stem if
your vehicle does not have DIC buttons,
for more than ve seconds. The oil life will
change to 100%.
If the CHANGE ENGINE OIL SOON message
comes back on when you start your vehicle, the
Engine Oil Life System has not reset. Repeat
the procedure.
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