2011 GMC SIERRA Owner's Manual

Black plate (11,1)GMC Sierra Owner Manual - 2011
Driving and Operating 9-11
Scanning the Terrain
Off-road driving can take you over
many different kinds of terrain.
Be familiar with the terrain and
its many different features.
Surface Conditions:Off-roading
surfaces can be hard-packed dirt,
gravel, rocks, grass, sand, mud,
snow, or ice. Each of these surfaces
affects the vehicle's steering,
acceleration, and braking in different
ways. Depending on the surface,
slipping, sliding, wheel spinning,
delayed acceleration, poor traction,
and longer braking distances can
occur. Surface Obstacles:
Unseen or
hidden obstacles can be hazardous.
A rock, log, hole, rut, or bump can
startle you if you are not prepared
for them. Often these obstacles are
hidden by grass, bushes, snow,
or even the rise and fall of the
terrain itself.
Some things to consider:
.Is the path ahead clear?
.Will the surface texture change
abruptly up ahead?
.Does the travel take you uphill or
downhill?
.Will you have to stop suddenly
or change direction quickly?
When driving over obstacles or
rough terrain, keep a firm grip on
the steering wheel. Ruts, troughs,
or other surface features can jerk
the wheel out of your hands. When driving over bumps, rocks,
or other obstacles, the wheels can
leave the ground. If this happens,
even with one or two wheels, you
cannot control the vehicle as well or
at all.
Because you will be on an unpaved
surface, it is especially important to
avoid sudden acceleration, sudden
turns, or sudden braking.
Off-roading requires a different kind
of alertness from driving on paved
roads and highways. There are no
road signs, posted speed limits,
or signal lights. Use good judgment
about what is safe and what is not.

Black plate (12,1)GMC Sierra Owner Manual - 2011
9-12 Driving and Operating
Driving on Hills
Off-road driving often takes you up,
down, or across a hill. Driving safely
on hills requires good judgment
and an understanding of what the
vehicle can and cannot do. There
are some hills that simply cannot be
driven, no matter how well built the
vehicle.
{WARNING
Many hills are simply too steep
for any vehicle. If you drive up
them, you will stall. If you drive
down them, you cannot control
your speed. If you drive across
them, you will roll over. You could
be seriously injured or killed.
If you have any doubt about the
steepness, do not drive the hill.
Approaching a Hill
When you approach a hill, decide
if it is too steep to climb, descend,
or cross. Steepness can be hard
to judge. On a very small hill, for
example, there may be a smooth,
constant incline with only a small
change in elevation where you can
easily see all the way to the top.
On a large hill, the incline may get
steeper as you near the top, but
you might not see this because the
crest of the hill is hidden by bushes,
grass, or shrubs.
Consider this as you approach a hill:
.Is there a constant incline,
or does the hill get sharply
steeper in places?
.Is there good traction on the
hillside, or will the surface cause
tire slipping?
.Is there a straight path up
or down the hill so you will
not have to make turning
maneuvers?
.Are there obstructions on the hill
that can block your path, such
as boulders, trees, logs, or ruts?
.What is beyond the hill? Is
there a cliff, an embankment, a
drop-off, a fence? Get out and
walk the hill if you do not know.
It is the smart way to find out.
.Is the hill simply too rough?
Steep hills often have ruts,
gullies, troughs, and exposed
rocks because they are more
susceptible to the effects of
erosion.

Black plate (13,1)GMC Sierra Owner Manual - 2011
Driving and Operating 9-13
Driving Uphill
Once you decide it is safe to drive
up the hill:
.Use a low gear and get a firm
grip on the steering wheel.
.Get a smooth start up the hill
and try to maintain speed.
Not using more power than
needed can avoid spinning
the wheels or sliding.
{WARNING
Turning or driving across steep
hills can be dangerous. You could
lose traction, slide sideways, and
possibly roll over. You could be
seriously injured or killed. When
driving up hills, always try to go
straight up.
.Try to drive straight up the hill if
at all possible. If the path twists
and turns, you might want to find
another route.
.Ease up on the speed as you
approach the top of the hill.
.Attach a flag to the vehicle to
be more visible to approaching
traffic on trails or hills.
.Sound the horn as you approach
the top of the hill to let opposing
traffic know you are there.
.Use headlamps even during the
day to make the vehicle more
visible to oncoming traffic.
{WARNING
Driving to the top (crest) of a
hill at full speed can cause an
accident. There could be a
drop-off, embankment, cliff,
or even another vehicle. You
could be seriously injured or
killed. As you near the top of a
hill, slow down and stay alert.If the vehicle stalls, or is about to
stall, and you cannot make it up
the hill:
.Push the brake pedal to stop
the vehicle and keep it from
rolling backwards and apply
the parking brake.
.If the engine is still running, shift
the transmission to R (Reverse),
release the parking brake, and
slowly back down the hill in
R (Reverse).
.If the engine has stopped
running, you need to restart it.
With the brake pedal pressed
and the parking brake still
applied, shift the transmission to
P (Park) and restart the engine.
Then, shift to R (Reverse),
release the parking brake,
and slowly back down the
hill as straight as possible
in R (Reverse).

Black plate (14,1)GMC Sierra Owner Manual - 2011
9-14 Driving and Operating
.While backing down the hill, put
your left hand on the steering
wheel at the 12 o'clock position
so you can tell if the wheels are
straight and can maneuver as
you back down. It is best to back
down the hill with the wheels
straight rather than in the left
or right direction. Turning the
wheel too far to the left or right
will increase the possibility of a
rollover.
Things not to do if the vehicle stalls,
or is about to stall, when going up
a hill:
.Never attempt to prevent a stall
by shifting into N (Neutral) to
rev-up the engine and regain
forward momentum. This will
not work. The vehicle can roll
backward very quickly and
could go out of control.
.Never try to turn around if about
to stall when going up a hill.
If the hill is steep enough to
stall the vehicle, it is steep
enough to cause it to roll over.
If you cannot make it up the hill,
back straight down the hill.
If, after stalling, you try to back
down the hill and decide you just
cannot do it, set the parking brake,
put your transmission in P (Park),
and turn off the engine. Leave
the vehicle and go get some help.
Exit on the uphill side and stay clear
of the path the vehicle would take
if it rolled downhill. Do not shift the
transfer case to Neutral when you
leave the vehicle. Leave it in
some gear.
{WARNING
Shifting the transfer case to
Neutral can cause your vehicle to
roll even if the transmission is in
P (Park). This is because the
Neutral position on the transfer
case overrides the transmission.
You or someone else could be
injured. If you are going to leave
your vehicle, set the parking
brake and shift the transmission
to P (Park). But do not shift the
transfer case to Neutral.

Black plate (15,1)GMC Sierra Owner Manual - 2011
Driving and Operating 9-15
Driving Downhill
When off-roading takes you
downhill, consider:
.How steep is the downhill? Will I
be able to maintain vehicle
control?
.What is the surface like?
Smooth? Rough? Slippery?
Hard-packed dirt? Gravel?
.Are there hidden surface
obstacles? Ruts? Logs?
Boulders?
.What is at the bottom of the hill?
Is there a hidden creek bank or
even a river bottom with large
rocks?
If you decide you can go down
a hill safely, try to keep the vehicle
headed straight down. Use a low
gear so engine drag can help the
brakes so they do not have to do all
the work. Descend slowly, keeping
the vehicle under control at all
times.
{WARNING
Heavy braking when going
down a hill can cause your
brakes to overheat and fade.
This could cause loss of control
and a serious accident. Apply the
brakes lightly when descending a
hill and use a low gear to keep
vehicle speed under control.
Things not to do when driving down
a hill:
.When driving downhill, avoid
turns that take you across the
incline of the hill. A hill that is
not too steep to drive down
might be too steep to drive
across. The vehicle could
roll over.
.Never go downhill with the
transmission in N (Neutral),
called free-wheeling. The brakes
will have to do all the work and
could overheat and fade.
Vehicles are much more likely to
stall when going uphill, but if it
happens when going downhill:
1. Stop the vehicle by applying the regular brakes and apply the
parking brake.
2. Shift to P (Park) and, while still braking, restart the engine.
3. Shift back to a low gear, release the parking brake, and drive
straight down.
4. If the engine will not start, get out and get help.

Black plate (16,1)GMC Sierra Owner Manual - 2011
9-16 Driving and Operating
Driving Across an Incline
An off-road trail will probably go
across the incline of a hill. To decide
whether to try to drive across the
incline, consider the following:
{WARNING
Driving across an incline that is
too steep will make your vehicle
roll over. You could be seriously
injured or killed. If you have any
doubt about the steepness of the
incline, do not drive across it.
Find another route instead.
.A hill that can be driven straight
up or down might be too steep
to drive across. When going
straight up or down a hill, the
length of the wheel base—the
distance from the front wheels to
the rear wheels —reduces the
likelihood the vehicle will tumble end over end. But when driving
across an incline, the narrower
track width
—the distance
between the left and right
wheels —might not prevent the
vehicle from tilting and rolling
over. Driving across an incline
puts more weight on the downhill
wheels which could cause a
downhill slide or a rollover.
.Surface conditions can be a
problem. Loose gravel, muddy
spots, or even wet grass can
cause the tires to slip sideways,
downhill. If the vehicle slips
sideways, it can hit something
that will trip it —a rock, a rut,
etc. —and roll over.
.Hidden obstacles can make the
steepness of the incline even
worse. If you drive across a rock
with the uphill wheels, or if the
downhill wheels drop into a rut
or depression, the vehicle can tilt
even more. For these reasons, carefully
consider whether to try to drive
across an incline. Just because
the trail goes across the incline
does not mean you have to drive it.
The last vehicle to try it might have
rolled over.
If you feel the vehicle starting
to slide sideways, turn downhill.
This should help straighten out
the vehicle and prevent the side
slipping. The best way to prevent
this is to
“walk the course” first, so
you know what the surface is like
before driving it.

Black plate (17,1)GMC Sierra Owner Manual - 2011
Driving and Operating 9-17
Stalling on an Incline
{WARNING
Getting out on the downhill (low)
side of a vehicle stopped across
an incline is dangerous. If the
vehicle rolls over, you could be
crushed or killed. Always get out
on the uphill (high) side of the
vehicle and stay well clear of the
rollover path.
If the vehicle stalls when crossing
an incline, be sure you, and
any passengers, get out on the
uphill side, even if the door there
is harder to open. If you get out on
the downhill side and the vehicle
starts to roll over, you will be right
in its path.
If you have to walk down the slope,
stay out of the path the vehicle will
take if it does roll over.
Driving in Mud, Sand, Snow,
or Ice
When you drive in mud, snow,
or sand, the wheels do not get
good traction. Acceleration is not
as quick, turning is more difficult,
and braking distances are longer.
It is best to use a low gear when
in mud —the deeper the mud, the
lower the gear. In really deep mud,
keep the vehicle moving so it does
not get stuck.
When driving on sand, wheel
traction changes. On loosely packed
sand, such as on beaches or sand
dunes, the tires will tend to sink into
the sand. This affects steering,
accelerating, and braking. Drive at
a reduced speed and avoid sharp
turns or abrupt maneuvers. Hard packed snow and ice offer
the worst tire traction. On these
surfaces, it is very easy to lose
control. On wet ice, for example,
the traction is so poor that you
will have difficulty accelerating.
And, if the vehicle does get moving,
poor steering and difficult braking
can cause it to slide out of control.
{WARNING
Driving on frozen lakes, ponds,
or rivers can be dangerous.
Underwater springs, currents
under the ice, or sudden thaws
can weaken the ice. Your vehicle
could fall through the ice and
you and your passengers could
drown. Drive your vehicle on safe
surfaces only.

Black plate (18,1)GMC Sierra Owner Manual - 2011
9-18 Driving and Operating
Driving in Water
{WARNING
Driving through rushing water can
be dangerous. Deep water can
sweep your vehicle downstream
and you and your passengers
could drown. If it is only shallow
water, it can still wash away the
ground from under your tires, and
you could lose traction and roll
the vehicle over. Do not drive
through rushing water.
Heavy rain can mean flash flooding,
and flood waters demand extreme
caution. Find out how deep the water is
before driving through it. Do not
try it if it is deep enough to cover
the wheel hubs, axles, or exhaust
pipe
—you probably will not get
through. Deep water can damage
the axle and other vehicle parts.
If the water is not too deep, drive
slowly through it. At faster speeds,
water splashes on the ignition
system and the vehicle can stall.
Stalling can also occur if you get the
tailpipe under water. If the tailpipe is
under water, you will never be able
to start the engine. When going
through water, remember that when
the brakes get wet, it might take
longer to stop. See Driving on Wet
Roads on page 9‑19.
After Off-Road Driving
Remove any brush or debris that
has collected on the underbody,
chassis, or under the hood. These
accumulations can be a fire hazard.
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.
The vehicle requires more frequent
service due to off-road use. Refer
to the Maintenance Schedule for
additional information.