2012 GMC SIERRA 1500 cooling

Black plate (5,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Climate Controls 8-5
0(Defrost):This mode removes
fog or frost from the windshield
more quickly. Air is directed to the
windshield and the side window
vents, with some air directed
to the floor vents. The system
automatically forces outside air into
the vehicle.
Do not drive the vehicle until all the
windows are clear.Dual Automatic Climate Control System
The heating, cooling, and ventilation in the vehicle can be controlled with
this system. The vehicle also has a flow-through ventilation system
described later in this section.
A. Driver and Passenger Temperature Controls
B. Fan Control
C. AUTO
D. Defrost
E. Recirculation
F. Outside Air G. Air Delivery Mode Control
H. Display
I. On/Off
J. Rear Window Defogger
K. Air Conditioning
L. PASS (Passenger)

Black plate (7,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Climate Controls 8-7
help quickly cool down the air
inside the vehicle. The light
on the button comes on in
recirculation.
2. Set the driver and passenger temperature.
To find your comfort setting, start
with a 23°C (74°F) temperature
setting and allow about
20 minutes for the system to
regulate. Use the driver or
passenger temperature buttons
to adjust the temperature setting
as necessary. If a temperature
setting of 15°C (60°F) is chosen,
the system remains at the
maximum cooling setting. If a
temperature setting of 32°C
(90°F) is chosen, the system
remains at the maximum heat
setting. Choosing either
maximum setting will not cause
the vehicle to heat or cool any
faster.
Do not cover the solar sensor
located on the top of the instrument
panel near the windshield. This sensor regulates air temperature
based on sun load. For more
information on the solar sensor, see
“Sensors”
later in this section.
To avoid blowing cold air in cold
weather, the system delays turning
the fan on until warm air is
available. The length of delay
depends on the engine coolant
temperature. Pressing the fan
switch overrides this delay and
changes the fan to a selected
speed.
Manual Operation
D C(Fan Control): Press these
buttons to increase or decrease the
fan speed.
Pressing either fan button while in
automatic control places the fan
under manual control. The fan
setting remains displayed and the
AUTO light turns off. The air
delivery mode remains under
automatic control.
H G(Air Delivery Mode Control):
Press these buttons to change the
direction of the airflow in the vehicle.
Repeatedly press either button until
the desired mode appears on the
display.
Pressing either mode button while
the system is off changes the air
delivery mode without turning the
system on.
Pressing either mode button while
in automatic control places the
mode under manual control. The air
delivery mode setting displays and
the AUTO light turns off. The fan
remains under automatic control.
H(Vent): Air is directed to the
instrument panel outlets.
)(Bi-Level): Air is divided
between the instrument panel and
floor outlets. Some air is directed
toward the windshield and side
window outlets.

Black plate (11,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Driving and Operating 9-11
After operation in mud or sand,
have the brake linings cleaned and
checked. These substances can
cause glazing and uneven braking.
Check the body structure, steering,
suspension, wheels, tires, and
exhaust system for damage and
check the fuel lines and cooling
system for any leakage.
More frequent maintenance
service is required. Refer to the
Maintenance Schedule for more
information.
Driving on Wet Roads
Rain and wet roads can reduce
vehicle traction and affect your
ability to stop and accelerate.
Always drive slower in these types
of driving conditions and avoid
driving through large puddles and
deep‐standing or flowing water.
{WARNING
Wet brakes can cause crashes.
They might not work as well in a
quick stop and could cause
pulling to one side. You could
lose control of the vehicle.
After driving through a large
puddle of water or a car/vehicle
wash, lightly apply the brake
pedal until the brakes work
normally.
Flowing or rushing water creates
strong forces. Driving through
flowing water could cause the
vehicle to be carried away. If this
happens, you and other vehicle
occupants could drown. Do not
ignore police warnings and be
very cautious about trying to drive
through flowing water.
Hydroplaning
Hydroplaning is dangerous. Water
can build up under the vehicle's
tires so they actually ride on the
water. This can happen if the road
is wet enough and you are going
fast enough. When the vehicle is
hydroplaning, it has little or no
contact with the road.
There is no hard and fast rule about
hydroplaning. The best advice is to
slow down when the road is wet.
Other Rainy Weather Tips
Besides slowing down, other wet
weather driving tips include:
.Allow extra following distance.
.Pass with caution.
.Keep windshield wiping
equipment in good shape.
.Keep the windshield washer fluid
reservoir filled.

Black plate (12,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
9-12 Driving and Operating
.Have good tires with proper
tread depth. SeeTires on
page 10‑50.
.Turn off cruise control.
Highway Hypnosis
Always be alert and pay attention to
your surroundings while driving.
If you become tired or sleepy, find
a safe place to park the vehicle
and rest.
Other driving tips include:
.Keep the vehicle well ventilated.
.Keep the interior
temperature cool.
.Keep your eyes moving —scan
the road ahead and to the sides.
.Check the rearview mirror and
vehicle instruments often.
Hill and Mountain Roads
Driving on steep hills or through
mountains is different than driving
on flat or rolling terrain. Tips for
driving in these conditions include:
.Keep the vehicle serviced and in
good shape.
.Check all fluid levels and brakes,
tires, cooling system, and
transmission.
.Shift to a lower gear when going
down steep or long hills.
{WARNING
If you do not shift down, the
brakes could get so hot that they
would not work well. You would
then have poor braking or even
none going down a hill. You could
crash. Shift down to let the engine
assist the brakes on a steep
downhill slope.
{WARNING
Coasting downhill in N (Neutral)
or with the ignition off is
dangerous. The brakes will have
to do all the work of slowing down
and they could get so hot that
they would not work well. You
would then have poor braking or
even none going down a hill. You
could crash. Always have the
engine running and the vehicle in
gear when going downhill.

Black plate (39,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Driving and Operating 9-39
the plus/minus button located on the
steering column lever is used to
change to the gear.
Grade Braking is not available when
Range Selection Mode is active.
SeeTow/Haul Mode on page 9‑39.
While using Range Selection Mode,
Cruise Control and the Tow/Haul
Mode can be used.
If the vehicle has an exhaust
brake, it can also be used, but will
not automatically downshift the
transmission. See Exhaust Brake in
the Duramax Diesel supplement.
Notice: Spinning the tires
or holding the vehicle in one
place on a hill using only the
accelerator pedal may damage
the transmission. The repair will
not be covered by the vehicle
warranty. If you are stuck, do not
spin the tires. When stopping on
a hill, use the brakes to hold the
vehicle in place.Low Traction Mode
If your vehicle has the Allison
Transmission, or the Hydra-Matic
6-Speed Automatic Transmission, it
has a Low Traction Mode that can
assist in vehicle acceleration when
road conditions are slippery, such
as with ice or snow. While the
vehicle is at a stop, select the
second gear range using Range
Selection Mode. This will limit
torque to the wheels after it detects
wheel slip, preventing the tires from
spinning.
Tow/Haul Mode
4-Speed Automatic Transmission
6-Speed Automatic Transmission
Vehicles with an automatic
transmission have a Tow/Haul
Mode. The Tow/Haul Mode adjusts
the transmission shift pattern to
reduce shift cycling, providing
increased performance, vehicle
control, and transmission cooling
when driving down steep hills or
Mountain grades, towing, or hauling
heavy loads.
The selector button is located on
the end of the shift lever. Turn
the Tow/Haul Mode on and off by
pressing the button. When the
Tow/Haul Mode is enabled, a light
on the instrument panel cluster will
come on.

Black plate (78,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
9-78 Driving and Operating
Maintenance when Trailer
Towing
The vehicle needs service more
often when pulling a trailer. See
Maintenance Schedule on
page 11‑3. Things that are
especially important in trailer
operation are automatic
transmission fluid, engine oil,
axle lubricant, belts, cooling
system, and brake system.
It is a good idea to inspect these
before and during the trip.
Check periodically to see that all
hitch nuts and bolts are tight.
Trailer Towing
If the vehicle has a diesel engine,
see the Duramax diesel supplement
for more information.
If the vehicle is a hybrid, see the
hybrid supplement for more
information.
Do not tow a trailer during break-in.
SeeNew Vehicle Break-In on
page 9‑25 for more information.{WARNING
The driver can lose control when
pulling a trailer if the correct
equipment is not used or the
vehicle is not driven properly.
For example, if the trailer is too
heavy, the brakes may not work
well or even at all. The driver and
passengers could be seriously
injured. The vehicle may also be
damaged; the resulting repairs
would not be covered by the
vehicle warranty. Pull a trailer
only if all the steps in this section
have been followed. Ask your
dealer for advice and information
about towing a trailer with the
vehicle.

Black plate (80,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
9-80 Driving and Operating
Use the following chart to determine how much the vehicle can weigh, based upon the vehicle model and options.
Weights listed apply for conventional trailers and fifth-wheel trailers unless otherwise noted.Vehicle Axle Ratio Maximum Trailer Weight GCWR (a)
1500 Series 2WD Regular Cab Standard Box
4.3L V6 (b) 3.232 177 kg (4,800 lbs) 4 309 kg (9,500 lbs)
4.3L V6 —With Automatic
Transmission (b) 3.73
2 449 kg (5,400 lbs) 4 536 kg (10,000 lbs)
4.3L V6 —With Manual
Transmission (b) 3.73
1 860 kg (4,100 lbs) 3 938 kg (8,683 lbs)
4.8L V8 (b) 3.232 132 kg (4,700 lbs) 4 309 kg (9,500 lbs)
4.8L V8 (b) 3.733 266 kg (7,200 lbs) 5 443 kg (12,000 lbs)
5.3L LMG V8 (b) 3.082 994 kg (6,600 lbs) 5 216 kg (11,500 lbs)
5.3L LMG V8, K5L HD
Cooling Pkg 3.08
3 357 kg (7,400 lbs) 5 534 kg (12,200 lbs)
5.3L LMG V8 K5L HD Cooling Pkg 3.42 4 128 kg (9,100 lbs) 6 350 kg (14,000 lbs)
1500 Series 2WD Extended Cab Standard Box 4.3L V6 (b) 3.231 996 kg (4,400 lbs) 4 309 kg (9,500 lbs)
4.8L V8 (b) 3.232 132 kg (4,700 lbs) 4 536 kg (10,000 lbs)
4.8L V8 (b) 3.733 039 kg (6,700 lbs) 5 443 kg (12,000 lbs)

Black plate (81,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Driving and Operating 9-81
VehicleAxle Ratio Maximum Trailer Weight GCWR (a)
5.3L V8 (b) 3.082 812 kg (6,200 lbs) 5 216 kg (11,500 lbs)
5.3L V8 K5L HD Cooling Pkg (b) 3.083 130 kg (6,900 lbs) 5 534 kg (12,200 lbs)
5.3L V8 K5L HD Cooling
Pkg —Conventional Trailer 3.42
4 400 kg (9,700 lbs) 6 804 kg (15,000 lbs)
5.3L V8 K5L HD Cooling
Pkg —Fifth-Wheel Trailer 3.42
4 264 kg (9,400 lbs) 6 804 kg (15,000 lbs)
6.2L V8 K5L HD Cooling
Pkg —Conventional Trailer 3.42
4 400 kg (9,700 lbs) 6 804 kg (15,000 lbs)
6.2L V8 K5L HD Cooling
Pkg —Fifth-Wheel Trailer 3.42
4 264 kg (9,400 lbs) 6 804 kg (15,000 lbs)
6.2L V8 NHT Max Trailering
Pkg —Conventional Trailer 3.73
4 853 kg (10,700 lbs) 7 257 kg (16,000 lbs)
6.2L V8 NHT Max Trailering
Pkg —Fifth-Wheel Trailer 3.73
4 808 kg (10,600 lbs) 7 257 kg (16,000 lbs)
1500 Series 2WD Crew Cab Short Box (b) 4.8L V8 3.232 132 kg (4,700 lbs) 4 536 kg (10,000 lbs)
4.8L V8 3.733 039 kg (6,700 lbs) 5 443 kg (12,000 lbs)
5.3L V8 (LMG) 3.082 812 kg (6,200 lbs) 5 216 kg (11,500 lbs)