
You can tow in DRIVE (D). You may want to shift
the transmission to THIRD (3) or, if necessary, a
lower gear selection if the transmission shifts
too often (e.g., under heavy loads and/or hilly
conditions).
Three important considerations have to do with weight:
the weight of the trailer,
the weight of the trailer tongue
and the weight on your vehicle’s tires.
Tow/Haul Mode
Tow/haul is a feature that assists when pulling a heavy
trailer or a large or heavy load. The purpose of the
tow/haul mode is to:
Reduce the frequency and improve the predictability
of transmission shifts when pulling a heavy trailer or
a large or heavy load.
Provide the same solid shift feel when pulling a
heavy trailer or a large or heavy load as when
the vehicle is unloaded.
Improve control of vehicle speed while requiring
less throttle pedal activity when pulling a heavy
trailer or a large or heavy load.
Your vehicle may be equipped with a switch at the end
of the shift lever which when pressed enables
tow/haul. When the switch is pressed, a light on theinstrument panel will illuminate to indicate that tow/haul
has been selected. Tow/haul may be turned off by
pressing the switch again, at which time the indicator
light on the instrument panel will turn off. The vehicle will
automatically turn off tow/haul every time it is started.
Tow/haul is designed to be most effective when the
vehicle and trailer combined weight is at least 75 percent
of the vehicle’s Gross Combined Weight Rating
(GCWR). See Weight of the Trailer later in this section.
Tow/haul is most useful under the following driving
conditions:
When pulling a heavy trailer or a large or heavy
load through rolling terrain.
When pulling a heavy trailer or a large or heavy
load in stop and go traffic.
When pulling a heavy trailer or a large or heavy
load in busy parking lots where improved low
speed control of the vehicle is desired.
Operating the vehicle in tow/haul when lightly loaded or
with no trailer at all will not cause damage. However,
there is no bene t to the selection of tow/haul when the
vehicle is unloaded. Such a selection when unloaded
may result in unpleasant engine and transmission driving
characteristics and reduced fuel economy. Tow/haul
is recommended only when pulling a heavy trailer or a
large or heavy load.
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2003 - Sierra Denali

Weight of the Trailer
How heavy can a trailer safely be?
It depends on how you plan to use your rig. For
example, speed, altitude, road grades, outside
temperature and how much your vehicle is used to pull
a trailer are all important. And, it can also depend
on any special equipment that you have on your vehicle.Use one of the following charts to determine how much
your vehicle can weigh, based upon your vehicle
model and options.
Maximum trailer weight is calculated assuming only the
driver is in the tow vehicle and it has all the required
trailering equipment. The weight of additional optional
equipment, passengers and cargo in the tow vehicle
must be subtracted from the maximum trailer weight.
Vehicle* Axle Ratio Maximum Trailer Weight GCWR
K-1500*
6000 V8 4.10 10,000 lbs. (4 535 kg)** 16,000 lbs. (7 264 kg)
*Tongue weight should be 10 percent to 15 percent of trailer weight up to 1,000 lbs. (454 kg). Fifth-wheel or
gooseneck kingpin weight should be 15 percent to 25 percent of trailer weight up to 1,500 lb. (680 kg) maximum.
**Maximum Trailer Weight 9,200 lbs for fth-wheel or gooseneck.
The Gross Combination Weight Rating (GCWR) is the
total allowable weight of the completely loaded
vehicle and trailer including any passengers, cargo,
equipment and conversions. The GCWR for your vehicle
should not be exceeded.
You can ask your dealer for our trailering information or
advice, or you can write us at the address listed in
your Warranty and Owner Assistance Information
Booklet.In Canada, write to:
General Motors of Canada Limited
Customer Communication Centre, 163-005
1908 Colonel Sam Drive
Oshawa, Ontario L1H 8P7
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2003 - Sierra Denali

Weight of Trailer Tongue
The tongue load (A) of any trailer is an important weight
to measure because it affects the total or gross weight
of your vehicle. The Gross Vehicle Weight (GVW)
includes the curb weight of the vehicle, any cargo you
may carry in it, and the people who will be riding in
the vehicle. And if you will tow a trailer, you must add
the tongue load to the GVW because your vehicle will be
carrying that weight, too. SeeLoading Your Vehicle
on page 4-47for more information about your vehicle’s
maximum load capacity.If you’re using a weight-carrying or a weight-distributing
hitch, the trailer tongue weight (A) should be 10 percent
to 15 percent of the total loaded trailer weight (B).
Do not exceed the maximum allowable tongue weight
for your vehicle.
After you’ve loaded your trailer, weigh the trailer and
then the tongue, separately, to see if the weights
are proper. If they aren’t, you may be able to get them
right simply by moving some items around in the
trailer.
Total Weight on Your Vehicle’s Tires
Be sure your vehicle’s tires are in ated to the upper limit
for cold tires. You’ll nd these numbers on the
Certi cation/Tire label at the rear edge of the driver’s
door or seeLoading Your Vehicle on page 4-47.
Then be sure you don’t go over the GVW or rear axle
limit for your vehicle, including the weight of the
trailer tongue. If you use a weight distributing hitch,
make sure you don’t go over the rear axle limit before
you apply the weight distribution spring.
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2003 - Sierra Denali

Hitches
It’s important to have the correct hitch equipment.
Crosswinds, large trucks going by and rough roads are
a few reasons why you’ll need the right hitch. Here
are some rules to follow:
If you’ll be pulling a trailer that, when loaded, will
weigh more than 5,000 lbs. (2 270 kg) be sure to
use a properly mounted, weight-distributing
hitch and sway control of the proper size. This
equipment is very important for proper vehicle
loading and good handling when you’re driving.
Safety Chains
You should always attach safety chains between your
vehicle and your trailer. Cross the safety chains
under the tongue of the trailer to help prevent the tongue
from contacting the road if it becomes separated from
the hitch.
You may attach the safety chains to the attaching point
on the hitch platform. Always leave just enough slack
so you can turn with your rig. Never allow safety chains
to drag on the ground.
Trailer Brakes
If your trailer weighs more than 2,000 lbs. (900 kg)
loaded, then it needs its own brakes–and they must be
adequate. Be sure to read and follow the instructions
for the trailer brakes so you’ll be able to install,
adjust and maintain them properly.
Your trailer brake system can tap into the vehicle’s
hydraulic brake system only if:
The trailer parts can withstand 3,000 psi
(20 650 kPa) of pressure.
The trailer’s brake system will use less than
0.02 cubic inch (0.3 cc) of uid from your vehicle’s
master cylinder. Otherwise, both braking systems
won’t work well. You could even lose your brakes.
If everything checks out this far, make the brake tap at
the port on the master cylinder that sends the uid
to the rear brakes. But don’t use copper tubing for this.
If you do, it will bend and nally break off. Use steel
brake tubing.
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2003 - Sierra Denali

Driving with a Trailer
Towing a trailer requires a certain amount of experience.
Before setting out for the open road, you’ll want to get
to know your rig. Acquaint yourself with the feel of
handling and braking with the added weight of the trailer.
And always keep in mind that the vehicle you are
driving is now a good deal longer and not nearly as
responsive as your vehicle is by itself.
Before you start, check the trailer hitch and platform
(and attachments), safety chains, electrical connector,
lamps, tires and mirror adjustment. If the trailer has
electric brakes, start your vehicle and trailer moving and
then apply the trailer brake controller by hand to be
sure the brakes are working. This lets you check your
electrical connection at the same time.
During your trip, check occasionally to be sure that the
load is secure, and that the lamps and any trailer
brakes are still working.
While towing a trailer or when exposed to long periods
of sunshine, the oor of the truck bed may become
very warm. Avoid putting items in the truck bed
that might be affected by high ambient temperatures.
Following Distance
Stay at least twice as far behind the vehicle ahead as
you would when driving your vehicle without a trailer.
This can help you avoid situations that require
heavy braking and sudden turns.
Passing
You’ll need more passing distance up ahead when
you’re towing a trailer. And, because you’re a good deal
longer, you’ll need to go much farther beyond the
passed vehicle before you can return to your lane.
Backing Up
Hold the bottom of the steering wheel with one hand.
Then, to move the trailer to the left, just move that hand
to the left. To move the trailer to the right, move your
hand to the right. Always back up slowly and, if possible,
have someone guide you.
Your vehicle is equipped with four-wheel steering and if
you use it while backing your trailer the same rules
apply. However, with four-wheel steering your rig will
respond more quickly and it may take additional practice
to get used to backing up with four-wheel steering.
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2003 - Sierra Denali

T
Tachometer....................................................3-26
Tailgate.........................................................2-10
Tailgate Removal............................................2-10
Taillamps.......................................................5-54
Temperature and Compass Display....................2-28
Testing the Alarm............................................2-14
Theft-Deterrent, Radio.....................................3-75
Theft-Deterrent Systems...................................2-13
Content Theft-Deterrent................................2-13
Passlock
®...................................................2-15
Tilt Wheel........................................................ 3-5
Tire Inflation Check.........................................6-10
Tires.............................................................5-56
Buying New Tires........................................5-60
Chains.......................................................5-64
Changing a Flat Tire....................................5-65
If a Tire Goes Flat.......................................5-64
Inflation -- Tire Pressure...............................5-57
Inspection and Rotation................................5-58
Spare Tire..................................................5-82
Uniform Tire Quality Grading.........................5-61
Wheel Alignment and Tire Balance
.................5-62
Wheel Replacement
.....................................5-62
When It Is Time for New Tires
......................5-59
To Use the Engine Coolant Heater
....................2-18
Tonneau Cover
...............................................2-39
Top Strap
......................................................1-39
Top Strap Anchor Location
...............................1-40Torque Lock...................................................2-25
Total Weight on Your Vehicle’s Tires..................4-56
Tow/Haul Mode ...............................................2-21
Tow/Haul Mode Light.......................................3-41
Towing
Recreational Vehicle.....................................4-47
Towing a Trailer..........................................4-53
Your Vehicle...............................................4-46
Traction
Manual Selectable Ride................................. 4-9
TRACTION ACTIVE........................................3-55
Trailer
Recommendations.......................................4-52
Trailer Brakes.................................................4-57
Trailer Wiring Harness.....................................4-61
Transfer Case................................................5-45
Transmission
Fluid, Automatic...........................................5-20
Temperature Gage.......................................3-36
TRANSMISSION HOT.....................................3-55
Transmission Operation, Automatic....................2-19
Transmission, Transaxle, Transfer Case Unit
Repair Manual............................................7-10
Transportation Options...................................... 7-7
Traveling to Remote Areas...............................4-20
Trip Information Button....................................3-43
Trip Odometer
................................................3-26
Truck-Camper Loading Information
....................4-50
Turn and Lane Change Signals
.......................... 3-6
TURN SIGNAL ON
.........................................3-54
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2003 - Sierra Denali

Turn Signal/Multifunction Lever........................... 3-5
Turn Signals When Towing a Trailer..................4-59
Two-Tiered Loading.........................................4-49
U
Underbody Flushing Service.............................6-13
Underhood Fuse Block....................................5-95
Understanding Radio Reception........................3-76
Uniform Tire Quality Grading............................5-61
United States................................................... 7-4
Using HomeLink
®...........................................2-38
Using the Recovery Hooks...............................4-45
V
Vehicle
Control........................................................ 4-5
Damage Warnings........................................... iv
Loading......................................................4-47
Symbols......................................................... iv
Vehicle Identification
Number (VIN).............................................5-90
Service Parts Identification Label
...................5-90
Vehicle Personalization
Memory Seat
..............................................2-41
Vehicle Storage
..............................................5-39
Visors
...........................................................2-13
Voltmeter Gage
..............................................3-33
W
Warning Lights, Gages and Indicators................3-24
Warnings
DIC Warnings and Messages........................3-51
Hazard Warning Flashers............................... 3-4
Other Warning Devices.................................. 3-4
Safety and Symbols......................................... iii
Vehicle Damage.............................................. iv
Washing Your Vehicle......................................5-85
Weatherstrip Lubrication...................................6-11
Weight of the Trailer........................................4-55
Weight of Trailer Tongue..................................4-56
What Kind of Engine Oil to Use........................5-15
What to Add ..................................................5-37
What to Do with Used Oil ................................5-17
What to Use ..................................5-24, 5-35, 5-46
Wheels
Alignment and Tire Balance..........................5-62
Replacement...............................................5-62
When to Add Engine Oil..................................5-14
When to Change Engine Oil (GM Oil Life
System).....................................................5-16
When to Check..............................................5-57
When to Check and Change
............................5-20
When to Check Lubricant
.................................5-46
When to Check Power Steering Fluid
................5-34
When to Inspect
.............................................5-18
When You Are Ready to Leave After Parking
on a Hill
.....................................................4-60
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2003 - Sierra Denali