tow GMC SIERRA 2008 Service Manual

Certain power accessory plugs may not be compatible
to the accessory power outlet and could result in
blown vehicle or adapter fuses. If you experience a
problem, see your dealer/retailer for additional
information on the accessory power plugs.
The accessory power outlets are powered, even when
the ignition is in LOCK/OFF. Continuing to use
power outlets while the ignition is in LOCK/OFF may
cause the vehicle’s battery to run down.
Notice:Adding any electrical equipment to your
vehicle may damage it or keep other components
from working as they should. The repairs would not
be covered by your warranty. Do not use equipment
exceeding maximum amperage rating of 20
amperes. Check with your dealer/retailer before
adding electrical equipment.
When adding electrical equipment, be sure to follow the
proper installation instructions included with the
equipment.
Notice:Improper use of the power outlet can cause
damage not covered by your warranty. Do not
hang any type of accessory or accessory bracket
from the plug because the power outlets are
designed for accessory power plugs only.Ashtray(s) and Cigarette Lighter
Your vehicle may have a front ashtray located near the
center of the instrument panel. Pull on the door to
open it. The ashtray may have a cigarette lighter.
Notice:If you put papers, pins, or other ammable
items in the ashtray, hot cigarettes or other
smoking materials could ignite them and possibly
damage your vehicle. Never put ammable items in
the ashtray.
To remove the ashtray, open the door and pull the
ashtray bin toward you. To replace the ashtray, insert
the ashtray bin inside the ashtray door and press down
until it engages. To use the cigarette lighter, push it
in all the way, and let go. When it is ready for use, the
lighter pops back out.
Notice:Holding a cigarette lighter in while it is
heating does not let the lighter back away from the
heating element when it is hot. Damage from
overheating can occur to the lighter or heating
element, or a fuse could be blown. Do not hold a
cigarette lighter in while it is heating.
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)(Bi-Level):Air is directed partly to the instrument
panel outlets and to the oor outlets. A little air is
directed towards the windshield and side window outlets.
Cooler air is directed to the upper outlets and warmer
air to the oor outlets.
6(Floor):Air is directed to the oor outlets, with
some to the windshield, side window outlets, and
second row oor outlets. In this mode, the system will
automatically select outside air.
-(Defog):See “Defogging and Defrosting” later in
this section.
@(Recirculation):Press this button to turn the
recirculation mode on. When the button is pressed, an
indicator light comes on.
This mode keeps outside air from entering the vehicle.
It can be used to reduce outside air and prevent
odors from entering the vehicle. Recirculation may also
help cool the air inside the vehicle more quickly once
the temperature inside the vehicle is less than the
outside temperature.
The recirculation mode cannot be used with oor, defog,
or defrost modes. If recirculation is selected with one
of those modes, the indicator light ashes three
times and then turns off. The air conditioning
compressor also comes on when this mode is activated.While in recirculation mode the windows may fog when
the weather is cold and damp. To clear the fog,
select either the defog or defrost mode and increase the
fan speed.
The recirculation mode can be turned off by pressing
the outside air button, or by turning off the ignition.
;(Outside Air):Press this button to turn on
the outside air mode. When this mode is selected, air
from outside the vehicle circulates throughout the
vehicle. An indicator light on the button comes on to
show that it is activated. The outside air mode can be
used with all modes, but it cannot be used with the
recirculation mode.
Air Conditioning
#
(Air Conditioning):Press this button to turn the
air conditioning (A/C) compressor on and off. When
air conditioning is selected, an indicator light comes on
to show that the air conditioning has been activated.
Pressing this button when the outside temperature is too
cool for air conditioning makes the air conditioning
indicator ash three times and then turn off to let you
know the air conditioning mode is not available. If the air
conditioning is on and the outside temperature drops
below a temperature which is too cool for air conditioning
to be effective, the air conditioning light turns off to show
that the air conditioning mode has been canceled.
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Speedometer and Odometer
Your speedometer lets you see your speed in both
miles per hour (mph) and kilometers per hour (km/h).
Your odometer shows how far your vehicle has
been driven, in either miles (used in the United States)
or kilometers (used in Canada).
Engine Hour Meter Display
The Driver Information Center (DIC) can also display
the number of hours the engine has run. To display the
engine hours, turn the ignition off, press and hold the
reset button for at least four seconds. The hour
meter will be displayed for up to 30 seconds, or until the
ignition is turned on. SeeDIC Operation and Displays
(With DIC Buttons) on page 3-55orDIC Operation
and Displays (Without DIC Buttons) on page 3-60for
more information.
Trip Odometer
The trip odometer can tell you how far your vehicle has
been driven since you last set the trip odometer to zero.
Press the reset button, located on the instrument panel
cluster next to the voltmeter, to toggle between the
trip odometer and the regular odometer. Holding
the reset button for approximately one second while the
trip odometer is displayed will reset it.
To display the odometer reading with the ignition off,
press the reset button.
SeeDIC Operation and Displays (With DIC Buttons) on
page 3-55orDIC Operation and Displays (Without
DIC Buttons) on page 3-60for more information.
Tachometer
Your tachometer displays the engine speed in
revolutions per minute (rpm). See “Grade Braking
(Allison Transmission
®)” underTow/Haul Mode on
page 2-34for more information.
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This light should come on briey when you turn the
ignition key to RUN. If it does not come on then, have it
xed so it will be ready to warn you if there is a
problem.
{CAUTION:
Your brake system may not be working properly
if the brake system warning light is on. Driving
with the brake system warning light on can lead
to an accident. If the light is still on after you
have pulled off the road and stopped carefully,
have the vehicle towed for service.
If the light comes on while you are driving, pull off the
road and stop carefully. You may notice that the pedal is
harder to push or may go closer to the oor. It may
take longer to stop. If the light is still on, have the vehicle
towed for service. SeeTowing Your Vehicle on
page 4-50.
Antilock Brake System Warning
Light
For vehicles with the
Antilock Brake System
(ABS), this light will come
on briey when you
start the engine.
That is normal. If the light does not come on then, have it
xed so it will be ready to warn you if there is a problem.
If the ABS light stays on, turn the ignition off, if the light
comes on when you are driving, stop as soon as it
is safely possible and turn the ignition off. Then start the
engine again to reset the system. If the ABS light still
stays on, or comes on again while you are driving, your
vehicle needs service. If the regular brake system
warning light is not on, you still have brakes, but you do
not have antilock brakes. If the regular brake system
warning light is also on, you do not have antilock brakes
and there is a problem with your regular brakes. See
Brake System Warning Light on page 3-44
For vehicles with a Driver Information Center (DIC), see
DIC Warnings and Messages on page 3-63for all
brake related DIC messages.
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If the Light is Flashing
The following can prevent more serious damage to your
vehicle:
Reduce vehicle speed.
Avoid hard accelerations.
Avoid steep uphill grades.
If you are towing a trailer, reduce the amount of
cargo being hauled as soon as it is possible.
If the light stops ashing and remains on steady, see “If
the Light Is On Steady” following.
If the light continues to ash, when it is safe to do so,
stop the vehicle. Find a safe place to park the vehicle.
Turn the ignition off, wait at least 10 seconds, and restart
the engine. If the light remains on steady, see “If the
Light Is On Steady” following. If the light is still ashing,
follow the previous steps and see your dealer/retailer
for service as soon as possible.
If the Light Is On Steady
You might be able to correct the emission system
malfunction by considering the following:
Did you recently put fuel into your vehicle?
If so, reinstall the fuel cap, making sure to fully install
the cap. SeeFilling the Tank on page 5-10. The
diagnostic system can determine if the fuel cap hasbeen left off or improperly installed. A loose or missing
fuel cap allows fuel to evaporate into the atmosphere.
A few driving trips with the cap properly installed should
turn the light off.
Did you just drive through a deep puddle of water?
If so, your vehicle’s electrical system might be wet. The
condition is usually corrected when the electrical system
dries out. A few driving trips should turn the light off.
Have you recently changed brands of fuel?
If so, be sure to fuel your vehicle with quality fuel. See
Gasoline Octane on page 5-6. Poor fuel quality causes
the engine not to run as efficiently as designed. You
might notice this as stalling after start-up, stalling when
you put the vehicle into gear, misring, hesitation on
acceleration, or stumbling on acceleration — these
conditions might go away once the engine is warmed up.
This will be detected by the system and cause the light to
turn on.
If you experience one or more of these conditions,
change the fuel brand you use. It will require at least
one full tank of the proper fuel to turn the light off.
If none of the above steps have made the light turn off,
your dealer/retailer can check the vehicle. Your
dealer/retailer has the proper test equipment and
diagnostic tools to x any mechanical or electrical
problems that might have developed.
3-49

Four-Wheel-Drive Light
The four-wheel-drive light
comes on when you shift a
manual transfer case
into four-wheel drive and
the front axle engages.
Some delay between the shifting and the light coming
on is normal.
SeeFour-Wheel Drive on page 2-36for more
information.
Tow/Haul Mode Light
This light comes on when
the Tow/Haul mode has
been activated.
For more information, seeTow/Haul Mode on page 2-34.
Fuel Gage
When the ignition is on, the fuel gage tells you about
how much fuel you have left in your tank.
The gage will rst indicate empty before you are out of
fuel, and you should get more fuel as soon as
possible.
When the fuel tank is low the FUEL LEVEL LOW
message will appear. SeeDIC Warnings and Messages
on page 3-63for more information.
United StatesCanada
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Also, be careful not to reset the OIL LIFE display
accidentally at any time other than when the oil has just
been changed. It cannot be reset accurately until the
next oil change. To reset the engine oil life system, see
Engine Oil Life System on page 5-18.
Units
Press the vehicle information button until UNITS
displays. This display allows you to select between
English or Metric units of measurement. Once in this
display, press the set/reset button to select between
ENGLISH or METRIC units. All of the vehicle information
will then be displayed in the unit of measurement
selected.
Tire Pressure
If your vehicle has the Tire Pressure Monitor System
(TPMS), the pressure for each tire can be viewed in the
DIC. The tire pressure will be shown in either pounds
per square inch (psi) or kilopascals (kPa). Press
the vehicle information button until the DIC displays
FRONT TIRES PSI (kPa) LEFT ## RIGHT ##. Press the
vehicle information button again until the DIC displays
REAR TIRES PSI (kPa) LEFT ## RIGHT ##.
If a low or high tire pressure condition is detected by the
system while driving, a message advising you to
check the pressure in a specic tire will appear in thedisplay. SeeInflation - Tire Pressure on page 5-74and
DIC Warnings and Messages on page 3-63for more
information.
If the tire pressure display shows dashes instead of a
value, there may be a problem with your vehicle. If this
consistently occurs, see your dealer/retailer for service.
Trailer Gain and Output
On vehicles with the Integrated Trailer Brake Control
(ITBC) system, the trailer brake display appears in the
DIC. Press the vehicle information button until
TRAILER GAIN and OUTPUT display.
TRAILER GAIN shows the trailer gain setting. This
setting can be adjusted from 0.0 to 10.0 with either a
trailer connected or disconnected. To adjust this setting,
see “Integrated Trailer Brake Control System” under
Towing a Trailer on page 4-55for more information.
OUTPUT shows the power output to the trailer anytime
a trailer with electric brakes is connected. Output is
displayed in 0 to 10 bars. Dashes may appear in
the OUTPUT display. See “Integrated Trailer Brake
Control System” underTowing a Trailer on page 4-55
for more information.
Engine Hours
Press the vehicle information button until ENGINE
HOURS displays. This display shows the total number
of hours the engine has run.
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Trip Odometer Reset Stem Menu Items
Odometer
Press the trip odometer reset stem until ODOMETER
displays. This display shows the distance the vehicle
has been driven in either miles (mi) or kilometers (km).
Engine Hours
To display the ENGINE HOURS, place the ignition in
LOCK/OFF or ACC/ACCESSORY, then press and hold
the trip odometer reset stem for four seconds while
viewing the ODOMETER. This display shows the total
number of hours the engine has run.
Trip Odometer
Press the trip odometer reset stem until TRIP displays.
This display shows the current distance traveled in
either miles (mi) or kilometers (km) since the last reset
for the trip odometer.
The trip odometer can be reset to zero by pressing and
holding the trip odometer reset stem while the trip
odometer is displayed.
The trip odometer has a feature called the retro-active
reset. This can be used to set the trip odometer to
the number of miles (kilometers) driven since the ignition
was last turned on. This can be used if the trip
odometer is not reset at the beginning of the trip.To use the retro-active reset feature, press and hold the
trip odometer reset stem for at least four seconds.
The trip odometer will display the number of miles (mi)
or kilometers (km) driven since the ignition was last
turned on and the vehicle was moving. Once the vehicle
begins moving, the trip odometer will accumulate
mileage. For example, if the vehicle was driven 5 miles
(8 km) before it is started again, and then the
retro-active reset feature is activated, the display will
show 5 miles (8 km). As the vehicle begins moving, the
display will then increase to 5.1 miles (8.2 km),
5.2 miles (8.4 km), etc.
Transmission Temperature
Press the trip odometer reset stem until TRANS
TEMP displays. This display shows the temperature
of the automatic transmission uid in either degrees
Fahrenheit (°F) or degrees Celsius (°C).
Trailer Gain and Output
On vehicles with the Integrated Trailer Brake Control
(ITBC) system, the trailer brake display appears in the
DIC. Press the trip odometer reset stem until TRAILER
GAIN and OUTPUT display.
TRAILER GAIN shows the trailer gain setting. This
setting can be adjusted from 0.0 to 10.0 with either a
trailer connected or disconnected. To adjust this setting,
see “Integrated Trailer Brake Control System” under
Towing a Trailer on page 4-55for more information.
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OUTPUT shows the power output to the trailer anytime
a trailer with electric brakes is connected. Output is
displayed in 0 to 10 bars. Dashes may appear in
the OUTPUT display. See “Integrated Trailer Brake
Control System” underTowing a Trailer on page 4-55
for more information.
Oil Life
To access this display, the vehicle must be in PARK (P).
Press the trip odometer reset stem until OIL LIFE
REMAINING displays. This display shows an estimate
of the oil’s remaining useful life. If you see 99% OIL LIFE
REMAINING on the display, that means 99% of the
current oil life remains. The engine oil life system
will alert you to change the oil on a schedule consistent
with your driving conditions.
When the remaining oil life is low, the CHANGE
ENGINE OIL SOON message will appear on the display.
See “CHANGE ENGINE OIL SOON” underDIC
Warnings and Messages on page 3-63. You should
change the oil as soon as you can. SeeEngine
Oil (Gasoline Engine) on page 5-15. In addition to the
engine oil life system monitoring the oil life, additional
maintenance is recommended in the Maintenance
Schedule in this manual. SeeScheduled Maintenance
(Gasoline Engine) on page 6-4for more information.
Remember, you must reset the OIL LIFE display
yourself after each oil change. It will not reset itself.Also, be careful not to reset the OIL LIFE display
accidentally at any time other than when the oil has just
been changed. It cannot be reset accurately until the
next oil change. To reset the engine oil life system, see
Engine Oil Life System on page 5-18.
Relearn Tire Positions
Your vehicle may have this display. To access this
display, the vehicle must be in PARK (P). If your vehicle
has the Tire Pressure Monitor System (TPMS), after
rotating the tires or after replacing a tire or sensor, the
system must re-learn the tire positions. To re-learn
the tire positions, seeTire Pressure Monitor System on
page 5-76. SeeTire Inspection and Rotation on
page 5-81andDIC Warnings and Messages on
page 3-63for more information.
Relearn Remote Key
To access this display, the vehicle must be in PARK (P).
This display allows you to match Remote Keyless
Entry (RKE) transmitters to your vehicle. To match an
RKE transmitter to your vehicle:
1. Press the trip odometer reset stem until RELEARN
REMOTE KEY displays.
2. Press and hold the trip odometer reset stem for
three seconds.
The message REMOTE KEY LEARNING ACTIVE
will display.
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is reconnected. This message also clears if you
acknowledge it. If this message still displays, either your
vehicle or the trailer needs service. See your
dealer/retailer.
See “Integrated Trailer Brake Control System” under
Towing a Trailer on page 4-55for more information.
DRIVER DOOR OPEN
This message displays and a chime sounds if the driver
door is not fully closed and the vehicle is in a drive
gear. Stop and turn off the vehicle, check the door for
obstructions, and close the door again. Check to
see if the message still appears on the DIC.
ENGINE HOT A/C (Air Conditioning)
TURNED OFF
This message displays when the engine coolant
becomes hotter than the normal operating temperature.
SeeEngine Coolant Temperature Gage on page 3-46.
To avoid added strain on a hot engine, the air
conditioning compressor automatically turns off. When
the coolant temperature returns to normal, the air
conditioning compressor turns back on. You can
continue to drive your vehicle.
If this message continues to appear, have the system
repaired by your dealer/retailer as soon as possible
to avoid damage to the engine.
ENGINE OVERHEATED IDLE ENGINE
Notice:If you drive your vehicle while the engine is
overheating, severe engine damage may occur. If
an overheat warning appears on the instrument
panel cluster and/or DIC, stop the vehicle as soon
as possible. SeeEngine Overheating on page 5-30
for more information.
This message displays when the engine coolant
temperature is too hot. Stop and allow the vehicle to
idle until it cools down. SeeEngine Coolant
Temperature Gage on page 3-46.
SeeOverheated Engine Protection Operating Mode (V8
Engines Only) on page 5-33for information on driving
to a safe place in an emergency.
ENGINE OVERHEATED STOP ENGINE
Notice:If you drive your vehicle while the engine
is overheating, severe engine damage may occur. If
an overheat warning appears on the instrument
panel cluster and/or DIC, stop the vehicle as soon
as possible. SeeEngine Overheating on page 5-30
for more information.
This message displays and a chime sounds if the
engine cooling system reaches unsafe temperatures for
operation. Stop and turn off the vehicle as soon as it
is safe to do so to avoid severe damage. This message
clears when the engine has cooled to a safe operating
temperature.
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