brake GMC SIERRA 2009 Repair Manual

Driving in Water
{CAUTION:
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 ash ooding, and ood 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. SeeDriving in Rain and on Wet
Roads on page 4-25.
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 re 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.
4-24

Driving at Night
Night driving is more dangerous than day driving
because some drivers are likely to be impaired — by
alcohol or drugs, with night vision problems, or by fatigue.
Night driving tips include:
Drive defensively.
Do not drink and drive.
Reduce headlamp glare by adjusting the inside
rearview mirror.
Slow down and keep more space between you and
other vehicles because headlamps can only light up
so much road ahead.
Watch for animals.
When tired, pull off the road.
Do not wear sunglasses.
Avoid staring directly into approaching headlamps.
Keep the windshield and all glass on your vehicle
clean — inside and out.
Keep your eyes moving, especially during turns or
curves.
No one can see as well at night as in the daytime.
But, as we get older, these differences increase.
A 50-year-old driver might need at least twice as much
light to see the same thing at night as a 20-year-old.
Driving in Rain and 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
owing water.
{CAUTION:
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 owing water could cause your
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 owing water.
4-25

Hill and Mountain Roads
Driving on steep hills or through mountains is different
than driving on at or rolling terrain. Tips for driving
in these conditions include:
Keep the vehicle serviced and in good shape.
Check all uid levels and brakes, tires, cooling
system, and transmission.
Going down steep or long hills, shift to a lower gear.
{CAUTION:
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.
{CAUTION:
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.
Stay in your own lane. Do not swing wide or cut
across the center of the road. Drive at speeds
that let you stay in your own lane.
Top of hills: Be alert — something could be in your
lane (stalled car, accident).
Pay attention to special road signs (falling rocks
area, winding roads, long grades, passing or
no-passing zones) and take appropriate action.
SeeOff-Road Driving on page 4-12for information
about driving off-road.
4-27

Winter Driving
Driving on Snow or Ice
Drive carefully when there is snow or ice between the
tires and the road, creating less traction or grip. Wet ice
can occur at about 32°F (0°C) when freezing rain begins
to fall, resulting in even less traction. Avoid driving on wet
ice or in freezing rain until roads can be treated with salt
or sand.
Drive with caution, whatever the condition. Accelerate
gently so traction is not lost. Accelerating too quickly
causes the wheels to spin and makes the surface
under the tires slick, so there is even less traction.
Try not to break the fragile traction. If you accelerate too
fast, the drive wheels will spin and polish the surface
under the tires even more.
TheStabiliTrak
®System on page 4-6improves the
ability to accelerate on slippery roads, but slow down
and adjust your driving to the road conditions. When
driving through deep snow, turn off the traction control
part of the StabiliTrak
®System to help maintain
vehicle motion at lower speeds.TheAntilock Brake System (ABS) on page 4-5improves
vehicle stability during hard stops on a slippery roads, but
apply the brakes sooner than when on dry pavement.
Allow greater following distance on any slippery road
and watch for slippery spots. Icy patches can occur on
otherwise clear roads in shaded areas. The surface
of a curve or an overpass can remain icy when the
surrounding roads are clear. Avoid sudden steering
maneuvers and braking while on ice.
Turn off cruise control, if equipped, on slippery surfaces.
Blizzard Conditions
Being stuck in snow can be in a serious situation. Stay
with the vehicle unless there is help nearby. If possible,
use theRoadside Assistance Program on page 7-7.
To get help and keep everyone in the vehicle safe:
Turn on theHazard Warning Flashers on page 3-8.
Tie a red cloth to an outside mirror.
4-28

For example, adding a 700 lb (318 kg) snow plow
actually adds more than 700 lbs (318 kg) to the front
axle. Using the formula, if the snow plow is 4 ft (122 cm)
in front of the front axle and the wheel base is 10 ft
(305 cm), then:
W = 700 lb (318 kg)
A = 4 ft (122 cm)
W.B. = 10 ft (305 cm)
(W x (A + W.B.))/W.B. = (700 x (4 + 10))/10 = 980 lbs
(445 kg)
So, if your truck’s front axle reserve capacity is more
than 980 lbs (445 kg), you could add the snow plow
without exceeding the front GAWR.
You can add heavier equipment on the front of the
vehicle if you compensate for it by carrying fewer
passengers, less cargo, or by positioning cargo towards
the rear. This has the effect of reducing the load on the
front. However, the front GAWR, rear GAWR, and the
Gross Vehicle Weight Rating (GVWR) must never be
exceeded.
{CAUTION:
On some vehicles that have certain front mounted
equipment, such as a snow plow, it may be possible
to load the front axle to the front gross axle weight
rating (GAWR) but not have enough weight on the
rear axle to have proper braking performance.
If your brakes can not work properly, you could
have a crash. To help your brakes work properly
when a snow plow is installed, always follow
the snow plow manufacturer or installer’s
recommendation for rear ballast to ensure a proper
front and rear weight distribution ratio, even though
the actual front weight may be less than the front
GAWR, and the total vehicle weight is less than the
gross vehicle weight rating (GVWR). Maintaining a
proper front and rear weight distribution ratio is
necessary to provide proper braking performance.
Total vehicle reserve capacity is the difference between
your GVWR and the weight of your truck with full fuel
and passengers. It is the amount of weight you can
add to your vehicle before reaching your GVWR.
4-41

Dinghy Towing
Two-Wheel-Drive Vehicles
Notice:If the vehicle is towed with all four wheels
on the ground, the drivetrain components could
be damaged. The repairs would not be covered by
the vehicle warranty. Do not tow the vehicle with
all four wheels on the ground.
Two-wheel-drive vehicles should not be towed
with all four wheels on the ground. Two-wheel-drive
transmissions have no provisions for internal lubrication
while being towed.
Four-Wheel-Drive Vehicles
Use the following procedure to dinghy tow a
four-wheel-drive vehicle:
1. Position the vehicle being towed behind the tow
vehicle and shift the transmission to P (Park).
2. Turn the engine off and rmly set the parking brake.
3. Securely attach the vehicle being towed to the
tow vehicle.
4-46

{CAUTION:
Shifting a four-wheel-drive vehicle’s transfer case
into N (Neutral) can cause the vehicle to roll even
if the transmission is in P (Park). The driver or
others could be injured. Make sure the parking
brake is rmly set before the transfer case is
shifted to N (Neutral).
4. Shift the transfer case to N (Neutral). See “Shifting
into Neutral” underFour-Wheel Drive on page 2-37
for the proper procedure to select the Neutral
position for the vehicle.
5. Release the parking brake only after the vehicle
being towed is rmly attached to the towing vehicle.
6. Turn the ignition to LOCK/OFF and remove the
key — the steering wheel will still turn.
After towing, see “Shifting Out of Neutral” under
Four-Wheel Drive on page 2-37for the proper procedure
to take the vehicle out of the Neutral position.
Dolly Towing
Front Towing (Front Wheels Off
the Ground)
Two-Wheel-Drive Vehicles
Notice:If a two-wheel-drive vehicle is towed with
the rear wheels on the ground, the transmission
could be damaged. The repairs would not be
covered by the vehicle warranty. Never tow the
vehicle with the rear wheels on the ground.
Two-wheel-drive vehicles should not be towed
with the rear wheels on the ground. Two-wheel-drive
transmissions have no provisions for internal lubrication
while being towed.
4-47

To dolly tow a two-wheel-drive vehicle, the vehicle
must be towed with the rear wheels on the dolly.
See “Rear Towing (Rear Wheels Off the Ground)”
later in this section for more information.
Four-Wheel-Drive Vehicles
Use the following procedure to dolly tow a
four-wheel-drive vehicle from the front:
1. Attach the dolly to the tow vehicle following the
dolly manufacturer’s instructions.
2. Drive the front wheels onto the dolly.
3. Shift the transmission to P (Park).
4. Firmly set the parking brake.
{CAUTION:
Shifting a four-wheel-drive vehicle’s transfer case
into N (Neutral) can cause the vehicle to roll even
if the transmission is in P (Park). The driver or
others could be injured. Make sure the parking
brake is rmly set before the transfer case is
shifted to N (Neutral).
5. Use an adequate clamping device designed for
towing to ensure that the front wheels are locked
into the straight position.
6. Secure the vehicle to the dolly following the
manufacturer’s instructions.
7. Shift the transfer case to N (Neutral). See “Shifting
into Neutral” underFour-Wheel Drive on page 2-37
for the proper procedure to select the neutral position
for the vehicle.
8. Release the parking brake only after the vehicle
being towed is rmly attached to the towing vehicle.
9. Turn the ignition to LOCK/OFF.
After towing, see “Shifting Out of Neutral” under
Four-Wheel Drive on page 2-37.
4-48

Rear Towing (Rear Wheels Off
the Ground)Two-Wheel-Drive Vehicles
Use the following procedure to dolly tow a
two-wheel-drive vehicle from the rear:
1. Attach the dolly to the tow vehicle following the
dolly manufacturer’s instructions.
2. Drive the rear wheels onto the dolly.
3. Firmly set the parking brake. SeeParking Brake on
page 2-50.
4. Put the transmission in P (Park).
5. Secure the vehicle to the dolly following the
manufacturer’s instructions.
6. Use an adequate clamping device designed for
towing to ensure that the front wheels are locked
into the straight position.
7. Turn the ignition to LOCK/OFF.
4-49

Four-Wheel-Drive Vehicles
Use the following procedure to dolly tow a
four-wheel-drive vehicle from the rear:
1. Attach the dolly to the tow vehicle following the
dolly manufacturer’s instructions.
2. Drive the rear wheels onto the dolly.
3. Firmly set the parking brake. SeeParking Brake on
page 2-50.
4. Put the transmission in P (Park).
5. Secure the vehicle to the dolly following the
manufacturer’s instructions.
6. Use an adequate clamping device designed for
towing to ensure that the front wheels are locked
into the straight position.{CAUTION:
Shifting a four-wheel-drive vehicle’s transfer case
into N (Neutral) can cause the vehicle to roll even
if the transmission is in P (Park). The driver or
others could be injured. Make sure the parking
brake is rmly set before the transfer case is
shifted to N (Neutral).
7. Shift the transfer case to N (Neutral). See “Shifting
into Neutral” underFour-Wheel Drive on page 2-37
for the proper procedure to select the neutral
position for the vehicle.
8. Turn the ignition to LOCK/OFF.
After towing, see “Shifting Out of Neutral” under
Four-Wheel Drive on page 2-37.
4-50