towing GMC SIERRA 2008 User Guide

A Four-Wheel Drive
indicator light comes on
when you shift into
four-wheel drive and the
front axle engages.
SeeFour-Wheel-Drive
Light on page 3-53
Some delay between shifting and when the indicator
light comes on is normal.
Recommended Transfer Case Settings
Driving ConditionsTransfer Case Settings
2m4m4nN
Normal YES
Severe YES
Extreme YES
Vehicle in Tow* YES
*SeeRecreational Vehicle Towing on page 4-50
Towing Your Vehicle on page 4-50Notice:Driving on clean, dry pavement in
four-wheel drive for an extended period of time can
cause premature wear on your vehicle’s powertrain.
Do not drive on clean, dry pavement in Four-Wheel
Drive for extended periods of time.
4
n(Four-Wheel-Drive Low):This setting also
engages the front axle and delivers extra torque. You
may never need Four-Wheel-Drive Low. It sends
maximum power to all four wheels. You might choose
Four-Wheel-Drive Low if you are driving off-road in deep
sand, deep mud, deep snow, and while climbing or
descending steep hills. When operating in Four-Wheel
Low, the gear ratio provides additional torque when
compared to Four-Wheel-Drive High. The transmission
gear shift feel is exaggerated.
2-37

A parking brake symbol
is located next to the
N (NEUTRAL) symbol
as a reminder to set the
parking brake before
shifting the transfer
case in Neutral.
{CAUTION:
Shifting the transfer case to NEUTRAL can
cause your vehicle to roll even if the
transmission is in PARK (P). You or someone
else could be seriously injured. Be sure to set
the parking brake before placing the transfer
case in NEUTRAL. SeeParking Brake on
page 2-49.N (NEUTRAL):Shift to this setting only when your
vehicle needs to be towed. SeeRecreational Vehicle
Towing on page 4-50orTowing Your Vehicle on
page 4-50.
2
m(Two-Wheel-Drive High):This setting is used for
driving in most street and highway situations. The
front axle is not engaged in two-wheel drive. This setting
also provides the best fuel economy.
4
m(Four-Wheel-Drive High):Use this setting when
you need extra traction, such as on snowy or icy
roads or in most off-road situations. This setting also
engages the front axle to help drive your vehicle. This is
the best setting to use when plowing snow.
You can shift from Two-Wheel-Drive High to
Four-Wheel-Drive High or Four-Wheel-Drive High to
Two-Wheel-Drive High while the vehicle is moving. In
extremely cold weather, it may be necessary to stop or
slow the vehicle to shift into Four-Wheel-Drive High.
2-38

Electronic Transfer Case
The transfer case knob is
located next to the
steering column.
Use the dial to shift into and out of four-wheel drive.
Recommended Transfer Case Settings
Driving ConditionsTransfer Case Settings
2m4m4nN
Normal YES
Severe YES
Extreme YES
Vehicle in Tow* YES
*SeeRecreational Vehicle Towing on page 4-50
Towing Your Vehicle on page 4-50You can choose among four driving settings:
Indicator lights in the dial show which setting you are in.
The indicator lights will come on briey when you turn
on the ignition and one will stay on. If the lights do
not come on, you should take your vehicle to your dealer
for service. An indicator light ashes while shifting the
transfer case and remains illuminated when the
shift is complete. If for some reason the transfer case
cannot make a requested shift, it will return to the
last chosen setting.
2
m(Two-Wheel-Drive High):This setting is used for
driving in most street and highway situations. The
front axle is not engaged in Two-Wheel Drive. This
setting also provides the best fuel economy.
4
m(Four-Wheel-Drive High):Use the
Four-Wheel-Drive High position when extra traction is
needed, such as on snowy or icy roads or in most
off-road situations. This setting also engages the front
axle to help drive your vehicle. This is the best setting to
use when plowing snow.
4
n(Four-Wheel-Drive Low):This setting also
engages the front axle and delivers extra torque. You
may never need this setting. It sends maximum power to
all four wheels. You might choose Four-Wheel-Drive
Low while driving off-road in deep sand, deep mud, deep
snow, and while climbing or descending steep hills.
StabiliTrak
®will not engage in this mode.
2-41

{CAUTION:
Shifting the transfer case to NEUTRAL can
cause your vehicle to roll even if the
transmission is in PARK (P). You or someone
else could be seriously injured. Be sure to set
the parking brake before placing the transfer
case in NEUTRAL. SeeParking Brake on
page 2-49.
N (NEUTRAL):Shift the vehicle’s transfer case to
NEUTRAL only when towing your vehicle. See
Recreational Vehicle Towing on page 4-50orTowing
Your Vehicle on page 4-50for more information.
If the SERVICE 4–Wheel Drive message stays on, you
should take your vehicle to your dealer for service.
See “Service 4–Wheel Drive message” underDIC
Warnings and Messages on page 3-63.
Shifting Into Two-Wheel-Drive High
Turn the knob to the Two-Wheel-Drive High position.
This can be done at any speed, except when shifting
from Four-Wheel-Drive Low. See Shifting Out of
Four-Wheel-Drive Low for more information.
Shifting Into Four-Wheel Drive Low
When Four-Wheel-Drive Low is engaged, vehicle speed
should be kept below 45 mph. Extended high-speed
operation in Four-Wheel-Drive Low may damage
or shorten the life of the drivetrain.
To shift to the Four-Wheel-Drive Low position, the
ignition must be in RUN and the vehicle must be
stopped or moving less than 3 mph (5 km/h) with the
transmission in NEUTRAL (N). The preferred method for
shifting into Four-Wheel-Drive Low is to have your
vehicle moving 1 to 2 mph (1.6 to 3.2 km/h). Turn the
knob to the Four-Wheel-Drive Low position. You
must wait for the Four-Wheel-Drive Low indicator light to
stop ashing and remain on before shifting your
transmission in gear.
Notice:Shifting the transmission into gear before
the requested mode indicator light has stopped
ashing could damage the transfer case. To
help avoid damaging your vehicle, always wait for
the mode indicator lights to stop ashing before
shifting the transmission into gear.
It is typical for your vehicle to exhibit signicant
engagement noise and bump when shifting between
Four-Wheel-Drive Low and Four-Wheel-Drive High
ranges or from NEUTRAL with the engine running.
2-42

{CAUTION:
Shifting the transfer case to NEUTRAL can
cause your vehicle to roll even if the
transmission is in PARK (P). You or someone
else could be seriously injured. Be sure to set
the parking brake before placing the transfer
case in NEUTRAL. SeeParking Brake on
page 2-49.
N (NEUTRAL):Shift the vehicle’s transfer case to
NEUTRAL only when towing your vehicle. See
Recreational Vehicle Towing on page 4-50orTowing
Your Vehicle on page 4-50for more information.
If the SERVICE 4–Wheel Drive message stays on, you
should take your vehicle to your dealer for service.
See “Service 4–Wheel Drive message” underDIC
Warnings and Messages on page 3-63.
Shifting Into Four-Wheel-Drive High or
AUTO (Automatic Four-Wheel Drive)
Turn the knob to the Four-Wheel-Drive High or AUTO
position. This can be done at any speed, except
when shifting from Four-Wheel-Drive Low, and the
indicator light will ash while shifting. It will remain on
when the shift is completed.
Shifting Into Two-Wheel-Drive High
Turn the knob to the Two-Wheel-Drive High position.
This can be done at any speed, except when shifting
from Four-Wheel-Drive Low.
Shifting Into Four-Wheel-Drive Low
When Four-Wheel-Drive Low is engaged, vehicle speed
should be kept below 45 mph. Extended high-speed
operation in Four-Wheel-Drive Low may damage
or shorten the life of the drivetrain.
To shift to the Four-Wheel-Drive Low position, the
ignition must be in RUN and the vehicle must be
stopped or moving less than 3 mph (5 km/h) with the
transmission in NEUTRAL (N). The preferred method for
shifting into Four-Wheel-Drive Low is to have your
vehicle moving 1 to 2 mph (1.6 to 3.2 km/h). Turn the
knob to the Four-Wheel-Drive Low position. You
must wait for the Four-Wheel-Drive Low indicator light to
stop ashing and remain on before shifting your
transmission in gear.
2-46

Parking Brake
To set the parking brake, hold the regular brake pedal
down with your right foot. Push down the parking
brake pedal with your left foot.
A chime sounds and the warning light ashes when the
parking brake is applied and the vehicle is moving at
least 5 mph (8 km/h).To release the parking brake, hold the regular brake
pedal down. Then pull the bottom edge of the lever, with
the parking brake symbol and located above the
parking brake pedal.
If the ignition is on when the parking brake is released,
the brake system warning light goes off.
Notice:Driving with the parking brake on can
overheat the brake system and cause premature
wear or damage to brake system parts. Make sure
that the parking brake is fully released and the brake
warning light is off before driving.
If you are towing a trailer and are parking on any hill,
seeTowing a Trailer on page 4-55.
2-49

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