2008 GMC SIERRA towing

Shifting Into PARK (P)
{CAUTION:
It can be dangerous to get out of your vehicle
if the shift lever is not fully in PARK (P) with
the parking brake rmly set. Your vehicle can
roll. If you have left the engine running, the
vehicle can move suddenly. You or others
could be injured. To be sure your vehicle will
not move, even when you are on fairly level
ground, use the steps that follow. With
four-wheel drive, if your transfer case is in
NEUTRAL, your vehicle will be free to roll,
even if your shift lever is in PARK (P). So, be
sure the transfer case is in a drive gear — not
in NEUTRAL. If you are pulling a trailer, see
Towing a Trailer on page 4-55.
1. Hold the brake pedal down with your right foot and
set the parking brake.
SeeParking Brake on page 2-49for more
information.2. Move the shift lever into the PARK (P) position by
pulling the shift lever toward you and moving it up
as far as it will go.
3. Be sure the transfer case is in a drive gear — not
in NEUTRAL (N).
4. Turn the ignition key to LOCK/OFF.
5. Remove the key and take it with you. If you can
leave your vehicle with the ignition key in your
hand, your vehicle is in PARK (P).
Leaving Your Vehicle With the Engine
Running
{CAUTION:
It can be dangerous to leave your vehicle with
the engine running. Your vehicle could move
suddenly if the shift lever is not fully in
PARK (P) with the parking brake rmly set.
CAUTION: (Continued)
2-50

Follow the proper steps to be sure your vehicle will not
move. SeeShifting Into PARK (P) on page 2-50.
If you are pulling a trailer, seeTowing a Trailer on
page 4-55.
Mirrors
Manual Rearview Mirror
When you are sitting in a comfortable driving position,
adjust the mirror so you can see clearly behind your
vehicle. Hold the mirror in the center to move it up or
down and side to side. The day/night adjustment allows
you to adjust the mirror to avoid glare from the lamps
behind you. Push the tab forward for daytime use
and pull it for nighttime use.
Automatic Dimming Rearview Mirror
with OnStar
®, Compass and
Temperature Display
Your vehicle may have this feature. When on, the
automatic dimming mirror dims to the proper level to
minimize glare from lights behind you after dark.
The mirror has a dual display in the upper right corner
of the mirror face that shows the compass reading
and the outside temperature.Control buttons for the OnStar
®system are at the
bottom of the mirror. SeeOnStar®System on page 2-65
for more information about the services OnStar®
provides.
P(On/Off):This is the on/off button.
Temperature and Compass Display
Press the on/off button, located to the far left, briey to
turn the compass/temperature display on or off.
If the display reads CAL, the compass needs to be
calibrated. For more information, see “Compass
Calibration” following.
To adjust between Fahrenheit and Celsius:
1. Press and hold the on/off button for approximately
four seconds until either a ashing F or C appears.
2. Press the button again to change the display to the
desired unit of measurement. After approximately
four seconds of inactivity, the new unit will be locked
in and the compass/temperature display will
return.
If an abnormal temperature reading is displayed for an
extended period of time, see your dealer/retailer.
Under certain circumstances, a delay in updating the
temperature is normal.
2-55

Outside Trailer-Tow Mirrors
If your vehicle has trailer towing type mirrors, they can
be adjusted so you can have a clear view of the
objects behind you. Manually pull out the mirror head to
extend it for better visibility when towing a trailer.
These mirrors can be manually folded forward or
rearward. The lower portion of the mirror is convex. A
convex mirror’s surface is curved so you can see
more from the driver’s seat. The convex mirror can be
adjusted manually to the driver’s preferred position
for better vision.
Your vehicle may have outside heated mirrors which
help clear them of condensation, snow, and ice. When
the rear window defogger button is pressed, the
heated mirrors are also turned on. Only the upper glassof the mirror is heated. The lower convex part of the
mirror is not heated.
Your mirror may also have a turn signal arrow that will
ash in the direction of the turn or lane change.
Outside Power Mirrors
If your vehicle is equipped
with outside power mirrors,
the controls are located
on the driver’s door
armrest.
Press (A) to select the driver’s side mirror. Then
press the arrows located on the four-way control
pad to adjust the mirror. Press (A) again to deselect
the mirror.
Press (B) to select the passenger’s side mirror.
Then press the arrows located on the four-way
control pad to adjust the mirror. Press (B) again to
deselect the mirror.
2-59

C. Driver Information Center (DIC) Buttons. SeeDriver
Information Center (DIC) on page 3-54.
D. Hazard Warning Flasher Button. SeeHazard
Warning Flashers on page 3-8.
E. Instrument Panel Cluster. SeeInstrument Panel
Cluster on page 3-35.
F. Shift Lever. SeeAutomatic Transmission Operation
on page 2-28. Tow/Haul Selector Button (If
Equipped). SeeTow/Haul Mode on page 2-34.
Range Selection Mode (Allison Transmission
®and
Hydra-Matic®6-Speed Button (If Equipped). See
Automatic Transmission Operation on page 2-28.
G. Audio System. SeeAudio System(s) on page 3-80.
H. Instrument Panel Storage Area. SeeInstrument
Panel Storage on page 2-75.
I. Integrated Trailer Brake Controller (If Equipped). See
Towing a Trailer on page 4-55.
J. Exterior Lamp Controls. SeeExterior Lamps on
page 3-17.
K. Hood Release. SeeHood Release on page 5-13.
L. Parking Brake. SeeParking Brake on page 2-49.
M. Dome Lamp Override Button. SeeDome Lamp
Override on page 3-21. Dome Lamp Knob. See
Dome Lamps on page 3-21. Fog Lamp Button
(If Equipped). SeeFog Lamps on page 3-20.
N. Cruise Control Buttons. SeeCruise Control on
page 3-14.
O. Tilt Wheel Lever. SeeTilt Wheel on page 3-9.P. Horn. SeeHorn on page 3-8.
Q. Audio Steering Wheel Controls (If Equipped). See
Audio Steering Wheel Controls on page 3-124.
R. Automatic Transfer Case Control (If Equipped). See
Four-Wheel Drive on page 2-36.
S. Ashtray (If Equipped). SeeAshtray(s) and Cigarette
Lighter on page 3-24.
T. StabiliTrak
®Button (If Equipped). SeeStabiliTrak®
System on page 4-6. Ultrasonic Rear Park Assist
Disable Button (If Equipped). SeeUltrasonic
Rear Parking Assist (URPA) on page 2-63. Pedal
Adjust Button (If Equipped). SeeAdjustable Throttle
and Brake Pedal on page 2-26. Heated Windshield
Washer Fluid Button (If Equipped).Windshield
Washer on page 3-13.
U. Accessory Power Outlet. SeeAccessory Power
Outlet(s) on page 3-23.
V. Climate Control System. SeeClimate Control
System (With Air Conditioning ) on page 3-25or
Climate Control System (Heater Only) on page 3-27
andDual Automatic Climate Control System on
page 3-28.
W. Power Take Off (PTO) Control (If Equipped). See
Power Take Off (PTO) in the DURAMAX
®Diesel
Supplement Index.
X. Passenger Airbag Off Control (If Equipped). See
Airbag Off Switch on page 1-76.
Y. Glove Box. SeeGlove Box on page 2-74.
3-5

A. Air Outlets. SeeOutlet Adjustment on page 3-33.
B. Turn Signal/Multifunction Lever. SeeTurn
Signal/Multifunction Lever on page 3-9.
C. Instrument Panel Cluster. SeeInstrument Panel
Cluster on page 3-35.
D. Hazard Warning Flasher Button. SeeHazard
Warning Flashers on page 3-8.
E. Shift Lever. SeeAutomatic Transmission Operation
on page 2-28.
F. Tow/Haul Selector Button (If Equipped). See
Tow/Haul Mode on page 2-34.
G. Driver Information Center (DIC) Controls. SeeDriver
Information Center (DIC) on page 3-54.
H. Audio System. SeeAudio System(s) on page 3-80.
I. Exterior Lamps Control. SeeExterior Lamps on
page 3-17.
J. Integrated Trailer Brake Controller (If Equipped). See
Towing a Trailer on page 4-55.
K. Dome Lamp Override Button. SeeDome Lamp
Override on page 3-21. Dome Lamp Knob.
SeeDome Lamps on page 3-21.
L. Automatic Transfer Case Control. (If Equipped). See
Four-Wheel Drive on page 2-36.
M. Hood Release. SeeHood Release on page 5-13.
N. Parking Brake. SeeParking Brake on page 2-49.O. Cruise Control Buttons. SeeCruise Control on
page 3-14.
P. Tilt Wheel Lever. SeeTilt Wheel on page 3-9.
Q. Horn. SeeHorn on page 3-8.
R. Audio Steering Wheel Controls. SeeAudio Steering
Wheel Controls on page 3-124.
S. Climate Controls. SeeClimate Control System (With
Air Conditioning ) on page 3-25orClimate Control
System (Heater Only) on page 3-27or Dual
Automatic Climate Controls (If Equipped). SeeDual
Automatic Climate Control System on page 3-28.
T. Accessory Power Outlets. SeeAccessory Power
Outlet(s) on page 3-23. Cigarette Lighter (If
Equipped). SeeAshtray(s) and Cigarette Lighter on
page 3-24.
U. StabiliTrak
®Button (If Equipped). SeeStabiliTrak®
System on page 4-6. Pedal Adjust Button (If
Equipped). SeeAdjustable Throttle and Brake Pedal
on page 2-26. Rear Park Assist Disable Button (If
Equipped). SeeUltrasonic Rear Parking Assist
(URPA) on page 2-63. Heated Windshield Washer
Fluid Button (If Equipped). SeeWindshield Washer
on page 3-13.
V. Passenger Airbag Off Control (If Equipped). See
Airbag Off Switch on page 1-76.
W. Glove Box. SeeGlove Box on page 2-74.
3-7

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.
3-45

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

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.
3-59