ECU GMC SIERRA DENALI 2004 Service Manual

{CAUTION:
Do not load your vehicle any heavier than the
GVWR, or either the maximum front or rear
GAWR. If you do, parts on your vehicle can
break, and it can change the way your vehicle
handles. These could cause you to lose
control and crash. Also, overloading can
shorten the life of your vehicle.
Notice:Overloading your vehicle may cause
damage. Repairs would not be covered by your
warranty. Do not overload your vehicle.
This will help you decide how much cargo and installed
equipment your truck can carry.
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'll keep going.
{CAUTION:
Things you put inside your vehicle can strike
and injure people in a sudden stop or turn, or
in a crash.
·Put things in the cargo area of your
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 your 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's also important loading information for off-road
driving in this manual. See ªLoading Your Vehicle
for Off-Road Drivingª under
Operating Your
All-Wheel-Drive Vehicle Off Paved Roads on page 4-18.
4-53

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). A
reinforcement kit for rail-mounted add-on equipment is
recommended. See your dealer.
4-54

Driving with a Trailer
{CAUTION:
If you have a rear-most window open and you
pull a trailer with your vehicle, carbon
monoxide (CO) could come into your vehicle.
You can not see or smell CO. It can cause
unconsciousness or death. See
Engine
Exhaust on page 2-29
. To maximize your safety
when towing a trailer:
·Have your exhaust system inspected for
leaks, and make necessary repairs before
starting on your trip.
·Keep the rear-most windows closed.
·If exhaust does come into your vehicle
through a window in the rear or another
opening, drive with your front, main
heating or cooling system on and with the
fan on any speed. This will bring fresh,
outside air into your vehicle. Do not use
the climate control setting for maximum air
because it only recirculates the air inside
your vehicle. See
Dual Automatic Climate
Control System on page 3-19.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 all trailer hitch parts 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.
4-65

Adding Coolant
If you need more coolant, add the proper DEX-COOLž
coolant mixtureat the surge tank, but only when the
engine is cool.
{CAUTION:
You can be burned if you spill coolant on hot
engine parts. Coolant contains ethylene glycol,
and it will burn if the engine parts are hot
enough. Do not spill coolant on a hot engine.
When replacing the pressure cap, make sure it is
hand-tight.
Coolant Surge Tank Pressure Cap
The coolant surge tank
pressure cap must be fully
installed on the coolant
surge tank.
Notice:If the pressure cap is not tightly installed,
coolant loss and possible engine damage may
occur. Be sure the cap is properly and tightly
secured.
5-24

Tire Inspection and Rotation
Tires should be rotated every 5,000 to 8,000 miles
(8 000 to 13 000 km).
Any time you notice unusual wear, rotate your tires as
soon as possible and check wheel alignment. Also
check for damaged tires or wheels. See
When It Is Time
for New Tires on page 5-69andWheel Replacement
on page 5-73for more information.
Make sure the spare tire is stored securely. Push, pull,
and then try to rotate or turn the tire. If it moves,
use the ratchet/wheel wrench to tighten the cable. See
Changing a Flat Tire on page 5-76.
The purpose of regular rotation is to achieve more
uniform wear for all tires on the vehicle. The ®rst rotation
is the most important. See
Scheduled Maintenance
on page 6-4.When rotating your tires, always use the correct rotation
pattern shown here.
Do not include the spare tire in your tire rotation.
After the tires have been rotated, adjust the front and
rear in¯ation pressures as shown on the tire and loading
information label. SeeLoading Your Vehicle on
page 4-48andIn¯ation - Tire Pressure on page 5-67,
for more information. Make certain that all wheel
nuts are properly tightened. See ªWheel Nut Torqueº
under
Capacities and Speci®cations on page 5-114.
5-68

4. Insert the hoist end (F)
through the hole (G) in
the rear bumper
and into the hoist
shaft.
5. Raise the tire part way upward. Make sure the
retainer is seated in the wheel opening.
6. Raise the tire fully against the underside of the
vehicle by turning the wheel wrench clockwise
until you hear two clicks or feel it skip twice. You
cannot overtighten the cable.A. Push and Pull
B. Rotate Tire
7. Make sure the tire is stored securely. Push, pull,
and then try to rotate or turn the tire. If the tire
moves, use the wheel wrench to tighten the cable.
Reinstall the spare tire lock (if equipped).
5-91

4. Repeat this procedure at least two times. If the
spare tire lowers to the ground, continue with
Step 5 of ªRemoving the Spare Tire and Toolsº
earlier in this section.
5. Turn the wrench counterclockwise until
approximately six inches (15 cm) of cable is
exposed.
6. Stand the wheel blocks
on their shortest ends,
with the backs
facing each other.7. Place the bottom edge of the jack on the wheel
blocks, separating them so that the jack is
balanced securely.
5-93

Engine Coolant Level Check
Check the engine coolant level and add
DEX-COOLžcoolant mixture if necessary. SeeEngine
Coolant on page 5-21for further details.
Windshield Washer Fluid Level Check
Check the windshield washer ¯uid level in the windshield
washer tank and add the proper ¯uid if necessary.
At Least Once a Month
Tire In¯ation Check
Visually inspect your tires and make sure tires are
in¯ated to the correct pressures. Do not forget to check
your spare tire. See
Tires on page 5-59for further
details. Check to make sure the spare tire is stored
securely. Push, pull and then try to rotate or turn
the spare tire. If it moves, tighten it. See
Changing a
Flat Tire on page 5-76.
At Least Once a Year
Starter Switch Check
{CAUTION:
When you are doing this inspection, the
vehicle could move suddenly. If the vehicle
moves, you or others could be injured.
1. Before you start, be sure you have enough room
around the vehicle.
2. Firmly apply both the parking brake and the regular
brake. See
Parking Brake on page 2-25if
necessary.
Do not use the accelerator pedal, and be ready to
turn off the engine immediately if it starts.
3. Try to start the engine in each gear. The starter
should work only in PARK (P) or NEUTRAL (N).
If the starter works in any other position, contact
your GM Goodwrench dealer for service.
6-10

Roadside Assistance Program
Security While You Travel
1-800-GMC-8782 (1-800-462-8782, Roadside
Assistance prompt)
As the proud owner of a new GMC vehicle, you are
automatically enrolled in the GMC Roadside Assistance
program. This value-added service is intended to
provide you with peace of mind as you drive in the city
or travel the open road. GMC's Roadside Assistance
toll-free number is staffed by courteous and capable
Roadside Assistance Representatives who are available
24 hours a day, 365 days a year.
We will provide the following services during the
Bumper-to-Bumper warranty period, at no expense
to you:
·Fuel Delivery:Delivery of enough fuel
($5 maximum) for the customer to get to the
nearest service station.
·Lock-out Service (identi®cation required):
Replacement keys or locksmith service will
be covered at no charge if you are unable to gain
entry into your vehicle. Delivery of the replacement
key will be covered within 10 miles.
·Emergency Tow:Tow to the nearest dealership for
warranty service or in the event of a
vehicle-disabling accident. Assistance when the
vehicle is mired in sand, mud or snow.
·Flat Tire Change:Installation of a spare tire will be
covered at no charge. (The customer is responsible
for the repair or replacement of the tire if not
covered by a warrantable failure.)
·Jump Start:No-start occurrences which require a
battery jump start will be covered at no charge.
·Dealer Locator Service
·Trip Routing:Your Roadside Assistance
Representative can provide you with speci®c
information regarding this feature.
·Trip Interruption Expense Bene®ts:Your
Roadside Assistance Representative can provide
you with speci®c information regarding this feature.
In many instances, mechanical failures are covered
under GMC's Bumper-to-Bumper warranty. However,
when other services are utilized, our Roadside
Assistance Representatives will explain any payment
obligations you might incur.
7-6

For prompt and efficient assistance when calling, please
provide the following to the Roadside Assistance
Representative:
·Your name, home address, and home telephone
number
·Telephone number of your location
·Location of the vehicle
·Model, year, color, and license plate number
·Mileage, Vehicle Identi®cation Number, and delivery
date of the vehicle
·Description of the problem
While we hope you never have the occasion to use our
service, it is added security while traveling for you
and your family. Remember, we are only a phone call
away. GMC Roadside Assistance: 1-800-462-8782,
text telephone (TTY) users, call 1-888-889-2438.
GMC reserves the right to limit services or
reimbursement to an owner or driver when, in GMC's
judgement, the claims become excessive in frequency or
type of occurrence.
Roadside Assistance is not part of or included in the
coverage provided by the New Vehicle Limited Warranty.
GMC reserves the right to make any changes or
discontinue the Roadside Assistance program at any
time without noti®cation.
Canadian Roadside Assistance
Vehicles purchased in Canada have an extensive
roadside assistance program accessible from anywhere
in Canada or the United States. Please refer to the
Warranty and Owner Assistance Information book.
Courtesy Transportation
GMC has always exempli®ed quality and value in its
offering of motor vehicles. To enhance your ownership
experience, we and our participating dealers are
proud to offer Courtesy Transportation, a customer
support program for new vehicles.
The Courtesy Transportation program is offered to retail
purchase/lease customers in conjunction with the
Bumper-to-Bumper coverage provided by the New
Vehicle Limited Warranty. Several transportation options
are available when warranty repairs are required.
This will reduce your inconvenience during warranty
repairs.
Plan Ahead When Possible
When your vehicle requires warranty service, you
should contact your dealer and request an appointment.
By scheduling a service appointment and advising
your service consultant of your transportation needs,
your dealer can help minimize your inconvenience.
7-7