2004 GMC SIERRA Rear axle

Seats and Restraint Systems........................... 1-1
Front Seats
............................................... 1-3
Rear Seats
............................................... 1-9
Safety Belts
.............................................1-11
Child Restraints
.......................................1-33
Air Bag Systems
......................................1-70
Restraint System Check
............................1-87
Features and Controls..................................... 2-1
Keys
........................................................ 2-3
Doors and Locks
....................................... 2-8
Windows
.................................................2-16
Theft-Deterrent Systems
............................2-19
Starting and Operating Your Vehicle
...........2-21
Mirrors
....................................................2-54
OnStar
žSystem
......................................2-64
Storage Areas
.........................................2-66
Vehicle Personalization
.............................2-69
Instrument Panel............................................. 3-1
Instrument Panel Overview
.......................... 3-4
Climate Controls
......................................3-21
Warning Lights, Gages and Indicators
.........3-33
Driver Information Center (DIC)
..................3-55
Audio System(s)
.......................................3-73Driving Your Vehicle....................................... 4-1
Your Driving, the Road, and Your Vehicle
..... 4-2
Towing
...................................................4-53
Service and Appearance Care.......................... 5-1
Service
..................................................... 5-3
Fuel
......................................................... 5-4
Checking Things Under the Hood
...............5-10
Rear Axle
...............................................5-59
Four-Wheel Drive
.....................................5-60
Noise Control System
...............................5-62
Bulb Replacement
....................................5-64
Windshield Wiper Blade Replacement
.........5-74
Tires
......................................................5-76
Appearance Care
...................................5-116
Vehicle Identi®cation
...............................5-125
Electrical System
....................................5-125
Capacities and Speci®cations
...................5-134
Maintenance Schedule..................................... 6-1
Maintenance Schedule
................................ 6-2
Customer Assistance and Information.............. 7-1
Customer Assistance and Information
........... 7-2
Reporting Safety Defects
...........................7-11
Index................................................................ 1
2004 GMC Sierra Owner ManualM

Recommended Transfer Case Settings
Transfer Case Settings
Driving
Conditions2HIAUTO
4WD4HI 4LO N
Normal YES
Variable YES
Severe YES
Extreme YES
Vehicle in
Tow*YES
*See ªRecreational Vehicle Towingº in the Index for
further information.
You can choose among four driving settings:
h(2HI):This setting is used for driving in most street
and highway situations. Your front axle is not engaged
in two- wheel drive. This setting also provides the
best fuel economy.AUTO 4WD:This setting is ideal for use when road
conditions are variable. When driving your vehicle
in AUTO 4WD, the front axle is engaged, but the
vehicle's power is sent to the rear wheels. When the
vehicle senses a loss of traction, the system will
automatically engage four-wheel drive. Driving in this
mode results in slightly lower fuel economy than 2HI.
G(4HI):Use 4HI when you need extra traction, such
a on snowy or icy roads or in most off-road situations.
This setting also engages your front axle to help
drive your vehicle. This is the best setting to use when
plowing snow.
g(4LO):This setting also engages your front axle
and delivers extra torque. You may never need 4LO. It
sends maximum power to all four wheels. You might
choose 4LO if you are driving off-road in deep
sand, deep mud, deep snow and climbing or descending
steep hills.
2-40

Your Driving, the Road, and Your Vehicle..........4-2
Defensive Driving...........................................4-2
Drunken Driving.............................................4-2
Control of a Vehicle........................................4-5
Braking.........................................................4-6
Traction Assist System (TAS)...........................4-9
Manual Selectable Ride.................................4-11
Locking Rear Axle........................................4-12
Steering......................................................4-12
QUADRASTEERŸ........................................4-14
Off-Road Recovery.......................................4-17
Passing.......................................................4-17
Loss of Control.............................................4-18
Off-Road Driving with Your Four-Wheel-Drive
Vehicle....................................................4-20
Driving at Night............................................4-37
Driving in Rain and on Wet Roads..................4-39
City Driving..................................................4-42Freeway Driving...........................................4-43
Before Leaving on a Long Trip.......................4-44
Highway Hypnosis........................................4-44
Hill and Mountain Roads................................4-45
Winter Driving..............................................4-47
If You Are Stuck: In Sand, Mud, Ice or Snow . . .4-51
Towing..........................................................4-53
Towing Your Vehicle.....................................4-53
Recreational Vehicle Towing...........................4-54
Loading Your Vehicle....................................4-57
Adding a Snow Plow or Similar Equipment.......4-64
Truck-Camper Loading Information..................4-68
Trailer Recommendations...............................4-70
Pickup Conversion to Chassis Cab..................4-70
Towing a Trailer...........................................4-70
Power Take-Off (PTO).................................4-101
Section 4 Driving Your Vehicle
4-1

FIRM (Loaded):Press the button to activate this
setting, the indicator light will be lit. Use this setting to
minimize trailer inputs to the vehicle or when the vehicle
is fully loaded. This setting is also appropriate for
off-road driving.
You can select a setting at any time based on road and
trailering conditions to provide the best ride and
handling. Select a new setting whenever driving
conditions change.
Locking Rear Axle
If your vehicle has this feature, your locking rear axle
can give you additional traction on snow, mud, ice, sand
or gravel. It works like a standard axle most of the
time, but when one of the rear wheels has no traction
and the other does, this feature will allow the wheel with
traction to move the vehicle.
Steering
Power Steering
If you lose power steering assist because the engine
stops or the system is not functioning, you can steer but
it will take much more effort.
Steering Tips
Driving on Curves
It is important to take curves at a reasonable speed.
A lot of the ªdriver lost controlº accidents mentioned on
the news happen on curves. Here is why:
Experienced driver or beginner, each of us is subject to
the same laws of physics when driving on curves.
The traction of the tires against the road surface makes
it possible for the vehicle to change its path when
you turn the front wheels. If there is no traction, inertia
will keep the vehicle going in the same direction. If
you have ever tried to steer a vehicle on wet ice, you
will understand this.
The traction you can get in a curve depends on the
condition of your tires and the road surface, the angle at
which the curve is banked, and your speed. While
you are in a curve, speed is the one factor you
can control.
Suppose you are steering through a sharp curve.
Then you suddenly accelerate. Both control
systems Ð steering and acceleration Ð have to do their
work where the tires meet the road. Adding the
sudden acceleration can demand too much of those
places. You can lose control. See
Traction Assist
System (TAS) on page 4-9.
4-12

Loading Your Vehicle for Off-Road
Driving
There are some important things to remember about
how to load your vehicle.
·The heaviest things should be on the load ¯oor and
forward of your rear axle. Put heavier items as far
forward as you can.
·Be sure the load is secured properly, so driving on
the off-road terrain does not toss things around.
{CAUTION:
·Cargo on the load ¯oor piled higher than
the seatbacks can be thrown forward
during a sudden stop. You or your
passengers could be injured. Keep cargo
below the top of the seatbacks.
·Unsecured cargo on the load ¯oor can be
tossed about when driving over rough
terrain. You or your passengers can be
struck by ¯ying objects. Secure the cargo
properly.
·Heavy loads on the roof raise the vehicle's
center of gravity, making it more likely to
roll over. You can be seriously or fatally
injured if the vehicle rolls over. Put heavy
loads inside the cargo area, not on the
roof. Keep cargo in the cargo area as far
forward and low as possible.
You will ®nd other important information in this manual.
See
Loading Your Vehicle on page 4-57andTires
on page 5-76.
4-23

Tire and Loading Information Label
A. Vehicle Capacity Weight
The Tire and Loading Information label is attached to
the center pillar, near the driver's door latch. Vehicles
without a center pillar will have the Tire and Loading
Information label attached to the driver's door edge. This
label lists the number of people that can be in your
vehicle and the total weight it can carry. This weight is
called the vehicle capacity weight.The Tire and Loading Information label also tells you
the size and recommended in¯ation pressure for
the original equipment tires on your vehicle. For more
information on tires and in¯ation see
Tires on page 5-76andIn¯ation - Tire Pressure on page 5-84
If your vehicle does not have the Tire and Loading
Information label, the Certi®cation/Tire label shows the
tire size and recommended in¯ation pressures
needed to obtain the Gross Vehicle Weight Rating
(GVWR) and the Gross Axle Weight Rating (GAWR) for
the front and rear axles. See ªCerti®cation/Tire Labelº
later in this section.
Steps for Determining Correct Load Limit
1. Locate the statement ªThe combined weight of
occupants and cargo should never exceed XXX
poundsº on your vehicle placard.
2. Determine the combined weight of the driver and
passengers that will be riding in your vehicle.
3. Subtract the combined weight of the driver and
passengers from XXX kilograms or XXX pounds.
4. The resulting ®gure equals the available amount of
cargo and luggage load capacity. For example, if the
ªXXXº amount equals 1400 lbs. and there will be
®ve 150 lb. passengers in your vehicle, the amount of
available cargo and luggage load capacity is 650 lbs.
(1400-750 (5 x 150) = 650 lbs.).
4-58

Certi®cation/Tire Label
The Certi®cation/Tire label is found on the rear edge of
the driver's door.
The label shows the size of your original tires and the
in¯ation pressures needed to obtain the gross weight
capacity of your vehicle. This is called the GVWR (Gross
Vehicle Weight Rating). The GVWR includes the
weight of the vehicle, all occupants, fuel and cargo.The Certi®cation/Tire label also tells you the maximum
weights for the front and rear axles, called Gross
Axle Weight Rating (GAWR). To ®nd out the actual loads
on your front and rear axles, you need to go to a
weigh station and weigh your vehicle. Your dealer can
help you with this. Be sure to spread out your load
equally on both sides of the centerline.
Never exceed the GVWR for your vehicle, or the GAWR
for either the front or rear axle.
The Certi®cation/Tire label also contains important
information about your Front Axle Reserve Capacity.
See ªFront Axle Reserve Capacityº later in this section.
And, if you do have a heavy load, you should spread
it out.{CAUTION:
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.
4-61

Payload
Payload capacity is the maximum load capacity that your
vehicle can carry. Be sure to include the weight of the
occupants as part of your load. If you added any
accessories or equipment after your vehicle left the
factory, remember to subtract the weight of these things
from the payload. Your dealer can help you with this.
Remember not to exceed the Gross Axle Weight Rating
(GAWR) of the front or rear axle.
Two-Tiered Loading
By positioning four 2º x 6º wooden planks across the
width of the pickup box, you can create an upper load
platform. The planks must be inserted in the pickup box
depressions. The length of the planks must allow for at
least a 3/4 inch (2 cm) bearing surface on each end of
the plank.
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 ¯areboard.
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.
Add-On Equipment
When you carry removable items, you may need to put a
limit on how many people you carry inside your vehicle.
Be sure to weigh your vehicle before you buy and install
the new equipment.
Notice:Overloading your vehicle may cause
damage. Repairs would not be covered by your
warranty. Do not overload your vehicle.
Remember not to exceed the Gross Axle Weight Rating
(GAWR) of the front or rear axle.
*Equipment Maximum Weight
Ladder Rack and Cargo 750 lbs. (340 kg)
Cross Toolbox and Cargo 400 lbs. (181 kg)
Side Boxes and Cargo 250 lbs. per side (113 kg
per side)
*The combined weight for all rail-mounted equipment
should not exceed 1,000 lbs. (454 kg) excludes
1500 crew cab models with 5' 8²box length. A
reinforcement kit for rail-mounted add-on equipment is
recommended. See your dealer. Ladder racks are not
recommended for 1500 crew cab models (with 5' 8²
pick-up box length.) Maximum recommended cross
mounted toolbox and cargo weight is 300 lbs. (136 kg)
for the 1500 crew cab (with 5' 8²pick-up box length.)
4-63