2012 GMC SIERRA 1500 ECU

Black plate (6,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
9-6 Driving and Operating
.Try to avoid sudden steering,
acceleration, or braking,
including reducing vehicle speed
by shifting to a lower gear. Any
sudden changes could cause
the tires to slide.
Remember: Antilock brakes help
avoid only the braking skid.
Off-Road Driving
Four-wheel-drive vehicles can be
used for off-road driving. Vehicles
without four-wheel drive and
vehicles not equipped with All
Terrain (AT) or On-Off Road (OOR)
tires must not be driven off-road
except on a level, solid surface. To
contact the tire manufacturer for
more information about the original
equipment tires, see the Limited
Warranty and Owner Assistance
Information manual.
Controlling the vehicle is the key to
successful off-road driving. One of
the best ways to control the vehicle
is to control the speed.
{WARNING
When driving off-road, bouncing
and quick changes in direction
can easily throw you out of
position. This could cause you to
lose control and crash. You and
your passengers should always
wear safety belts.
Before Driving Off-Road
.Have all necessary maintenance
and service work completed.
.Fuel the vehicle, fill fluid levels,
and check inflation pressure in
all tires, including the spare,
if equipped.
.Read all the information about
four-wheel-drive vehicles in this
manual.
.Make sure all underbody
shields, if equipped, are properly
attached.
.Know the local laws that apply to
off-road driving. To gain more ground clearance if
needed, it may be necessary to
remove the front fascia lower
air dam.
Notice:
Operating the vehicle
for extended periods without
the front fascia lower air dam
installed can cause improper air
flow to the engine. Re‐attach the
front fascia air dam after off-road
driving.
Loading the Vehicle for
Off-Road Driving
{WARNING
.Unsecured cargo on the
load floor can be tossed
about when driving over
rough terrain. You or your
passengers can be struck by
flying objects. Secure the
cargo properly.
(Continued)

Black plate (20,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
9-20 Driving and Operating
The Certification/Tire label also
contains important information
about your Front Axle Reserve
Capacity. See“What is front axle
reserve capacity, and how do I
calculate it?” underAdding a
Snow Plow or Similar Equipment
on page 9‑106.
{WARNING
In the case of a sudden stop
or collision, things carried in
the bed of your truck could
shift forward and come into
the passenger area, injuring
you and others. If you put
things in the bed of your truck,
you should make sure they
are properly secured.
{WARNING
Do not load the vehicle any
heavier than the Gross
Vehicle Weight Rating
(GVWR), or either the
maximum front or rear Gross
Axle Weight Rating (GAWR).
This can cause systems to
break and change the way the
vehicle handles. This could
cause loss of control and a
crash. Overloading can also
shorten the life of the vehicle.
Notice: Overloading the
vehicle may cause damage.
Repairs would not be covered
by the vehicle warranty. Do
not overload the vehicle. Using heavier suspension
components to get added
durability might not change
your weight ratings. Ask your
dealer to help you load your
vehicle the right way.
If you put things inside your
vehicle
—like suitcases,
tools, packages, or anything
else —they go as fast as the
vehicle goes. If you have to stop
or turn quickly, or if there is a
crash, they will keep going.

Black plate (21,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Driving and Operating 9-21
{WARNING
Things you put inside the
vehicle can strike and injure
people in a sudden stop or
turn, or in a crash.
.Put things in the cargo
area of the vehicle. Try to
spread the weight evenly.
.Never stack heavier
things, like suitcases,
inside the vehicle so that
some of them are above
the tops of the seats.
.Do not leave an
unsecured child restraint
in the vehicle.
.When you carry something
inside the vehicle, secure
it whenever you can.
.Do not leave a seat folded
down unless you need to. There is also important loading
information for off-road driving
in this manual. See
“Loading
Your Vehicle for Off-Road
Driving“under Off-Road Driving
on page 9‑6.
Two-Tiered Loading
Depending on the model of your
pick‐up, an upper load platform
can be created by positioning
three or four 5 cm (2 inches) by
15 cm (6 inches) wooden planks
across the width of the pickup
box. The planks must be
inserted in the pickup box
depressions. When using this upper load
platform, be sure the load is
securely tied down to prevent it
from shifting. The load's center
of gravity should be positioned
in a zone over the rear axle.
The zone is located in the area
between the front of each wheel
well and the rear of each wheel
well. The center of gravity height
must not extend above the top
of the pickup box flareboard.
Any load that extends beyond
the vehicle's taillamp area must
be properly marked according to
local laws and regulations.
Remember not to exceed
the Gross Axle Weight
Rating (GAWR) of the front or
rear axle.

Black plate (24,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
9-24 Driving and Operating
Here is an example of proper
truck and camper match:
A.Camper Center of Gravity
B.Recommended Center of
Gravity Location Zone
When the truck is used to carry
a slide‐in camper, the total cargo
load of the truck consists of the
manufacturer's camper weight
figure, the weight of installed
additional camper equipment not
included in the manufacturer's
camper weight figure, the weight of camper cargo, and the weight
of passengers in the camper.
The total cargo load should not
exceed the truck's cargo weight
rating, and the camper's center
of gravity (A) should fall within
the truck's recommended
center of gravity zone (B) when
installed.
Any accessories or other
equipment that are added to the
vehicle must be weighed. Then,
subtract this extra weight from
the CWR. This extra weight may
shorten the center of gravity
zone of the vehicle.
If the slide-in camper and its
load weighs less than the CWR,
the center of gravity zone for
your vehicle may be larger.
Secure loose items to prevent
weight shifts that could affect the
balance of the vehicle. When the
truck‐camper is loaded, drive to
a scale and weigh on the frontand on the rear wheels
separately to determine axle
loads. Individual axle loads
should not exceed either of
the gross axle weight ratings
(GAWR). The total axle loads
should not exceed your vehicle's
gross vehicle weight rating
(GVWR). These ratings are
given on the vehicle certification
label attached to the rear
edge of the driver door. See
“Certification/Tire Label”
under
Vehicle Load Limits on
page 9‑16. If weight ratings are
exceeded, move or remove
items to bring all weights below
the ratings.
See your dealer for more
information on curb weights,
cargo weights, Cargo Weight
Rating and the correct center of
gravity zone.

Black plate (30,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
9-30 Driving and Operating
Engine Coolant Heater
The engine heater can provide
easier starting and better fuel
economy during engine warm-up
in cold weather conditions at or
below−18°C (0°F). Vehicles with an
engine heater should be plugged in
at least four hours before starting.
An internal thermostat in the
plug-end of the cord may exist
which will prevent engine coolant
heater operation at temperatures
above −18°C (0°F).
If the vehicle has a diesel engine,
see the Duramax Diesel supplement
for more information.
To Use the Engine Coolant
Heater
1. Turn off the engine.
2. Open the hood and unwrap the electrical cord. The cord
is secured to the Engine
Compartment Fuse Block with
a clip. Carefully remove the wire tie which bundles the
electrical plug. Do not cut the
electrical cord.
3. Plug the cord into a normal, grounded 110-volt AC outlet.
{WARNING
Plugging the cord into an
ungrounded outlet could cause an
electrical shock. Also, the wrong
kind of extension cord could
overheat and cause a fire. You
could be seriously injured. Plug
the cord into a properly grounded
three-prong 110-volt AC outlet.
If the cord will not reach, use a
heavy-duty three-prong extension
cord rated for at least 15 amps.
4. Before starting the engine, be sure to unplug and store the
cord as it was before to keep
it away from moving engine
parts. If you do not, it could be
damaged. The length of time the heater should
remain plugged in depends on
several factors. Ask a dealer in the
area where you will be parking the
vehicle for the best advice on this.
Shifting Into Park
{WARNING
It can be dangerous to get out of
the vehicle if the shift lever is not
fully in P (Park) with the parking
brake firmly set. The vehicle can
roll. If you have left the engine
running, the vehicle can move
suddenly. You or others could be
injured. To be sure the vehicle will
not move, even when you are on
fairly level ground, use the steps
that follow. With four-wheel
drive, if the transfer case is in
N (Neutral), the vehicle will be
free to roll, even if the shift lever
is in P (Park). So, be sure the
transfer case is in a drive
(Continued)

Black plate (67,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Driving and Operating 9-67
Reverse this procedure to reinstall
the RVC and make sure the
grommet and connection are
secure.
When the System Does Not
Seem To Work Properly
The RVC system might not work
properly or display a clear image if:
.The RVC is turned off. See
“Turning the RVC System On or
Off”earlier in this section.
.It is dark.
.The sun or the beam of
headlamps is shining directly
into the camera lens.
.Ice, snow, mud, or anything else
builds up on the camera lens.
Clean the lens, rinse it with
water, and wipe it with a soft
cloth.
.The back of the vehicle is in
an accident, the position and
mounting angle of the camera
can change or the camera can
be affected. Be sure to have the
camera and its position and
mounting angle checked at your
dealer.
The RVC system display in the
rearview mirror may turn off or not
appear as expected due to one of
the following conditions. If this
occurs the left indicator light on the
mirror will flash.
.A slow flash may indicate a loss
of video signal, or no video
signal present during the reverse
cycle.
.A fast flash may indicate that
the display has been on for
the maximum allowable time
during a reverse cycle, or the
display has reached an Over
Temperature limit. The fast flash conditions are
used to protect the video
device from high temperature
conditions. Once conditions
return to normal the device will
reset and the green indicator will
stop flashing.
During any of these fault conditions,
the display will be blank and the
indicator will flash while the vehicle
is in R (Reverse) or until the
conditions return to normal.
Press and hold
zwhen the left
indicator light is flashing to turn off
the video display along with the left
indicator light.

Black plate (75,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Driving and Operating 9-75
Driving with a Trailer
{WARNING
When towing a trailer, exhaust
gases may collect at the rear of
the vehicle and enter if the
liftgate, trunk/hatch, or rear-most
window is open.
Engine exhaust contains Carbon
Monoxide (CO) which cannot be
seen or smelled. It can cause
unconsciousness and even death.
To maximize safety when towing
a trailer:
.Have the exhaust system
inspected for leaks and make
necessary repairs before
starting a trip.
.Never drive with the liftgate,
trunk/hatch, or rear-most
window open.(Continued)
WARNING (Continued)
.Fully open the air outlets on
or under the instrument
panel.
.Adjust the Climate Control
system to a setting that
brings in only outside air and
set the fan speed to the
highest setting. See Climate
Control System in the Index.
For more information about
Carbon Monoxide, see Engine
Exhaust on page 9‑33.
Towing a trailer requires a certain
amount of experience. The
combination you are driving is
longer and not as responsive as the
vehicle itself. Get acquainted with
the handling and braking of the rig
before setting out for the open road.
Before starting, check all trailer
hitch parts and attachments,
safety chains, electrical connectors, lamps, tires, and mirrors. If the
trailer has electric brakes, start the
combination moving and then apply
the trailer brake controller by hand
to be sure the brakes work.
During the trip, check occasionally
to be sure that the load is secure
and the lamps and any trailer
brakes still work.
Following Distance
Stay at least twice as far behind the
vehicle ahead as you would when
driving the vehicle without a trailer.
This can help to avoid heavy
braking and sudden turns.
Passing
More passing distance is needed
when towing a trailer. The
combination will not accelerate
as quickly and is longer so it is
necessary to go much farther
beyond the passed vehicle before
returning to the lane.

Black plate (92,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
9-92 Driving and Operating
Ask your dealer for trailering
information or advice, or write us at
our Customer Assistance Offices.
SeeCustomer Assistance Offices
(U.S. and Canada) on page 13‑4 or
Customer Assistance Offices
(Mexico) on page 13‑5 for more
information.Weight of the Trailer Tongue
The tongue load (A) of any trailer is
very important because it is also
part of the vehicle weight. The
Gross Vehicle Weight (GVW)
includes the curb weight of the
vehicle, any cargo carried in it, and
the people who will be riding in the
vehicle as well as trailer tongue
weight. Vehicle options, equipment,
passengers and cargo in the vehicle
reduce the amount of tongue weight
the vehicle can carry, which will also
reduce the trailer weight the vehicle
can tow. See “Vehicle Load Limits”
for more information about the
vehicle's maximum load capacity.
Trailer tongue weight (A) should be
10 to 15 percent and fifth-wheel or
gooseneck kingpin weight should be
15 to 25 percent of the loaded trailer
weight up to the maximums for
vehicle series and hitch type.: