brake GMC SIERRA DENALI 2003 Service Manual

Driving On Grades
Reduce speed and shift to a lower gear before you start
down a long or steep downgrade.
If you don’t shift
down, you might have to use your brakes
so much that
they would get hot and no longer work well.
You can tow in DRIVE
(5). 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).
You may also want to activate the tow/haul mode
if the
transmission shifts too often. See “Tow/Haul Mode”
earlier in this section.
When towing at high altitude on steep uphill grades,
consider the following: Engine coolant will boil at a lower
temperature than at normal altitudes.
If you turn your
engine
off immediately after towing at high altitude
on steep uphill grades, your vehicle may show signs
similar
to engine overheating. To avoid this, let the
engine run while parked (preferably on level ground)
with the automatic transmission in PARK (P) for a
few minutes before turning the engine
off. If you do get
the overheat warning, see
Engine Overheating on
page
5-27.
Parking on Hills
m
You really should not park your vehicle, with a
trailer attached, on a hill.
If something goes
wrong, your rig could start to move. People
can be injured, and both your vehicle and the
trailer can be damaged.
But
if you ever have to park your rig on a hill, here’s
how to do it:
1. Apply your regular brakes, but don’t shift into
PARK
(P) yet.
2. Have someone place chocks under the trailer
wheels.
3. When the wheel chocks are in place, release the
regular brakes until the chocks absorb the load.
4. Reapply the regular brakes. Then apply your
parking brake and shift into PARK (P).
5. Release the regular brakes.
4-58

When You Are Ready to Leave After
Parking on a
Hill
1. Apply your regular brakes and hold the pedal down
while you:
0 start your engine,
shift into a gear, and
0 release the parking brake.
2. Let up on the brake pedal.
3. Drive slowly until the trailer is clear of the chocks.
4. Stop and have someone pick up and store the
chocks.
Maintenance When Trailer Towing
Your vehicle will need service more often when you’re
pulling a trailer. See the Maintenance Schedule for more
on this. Things that are especially important in trailer
operation are automatic transmission fluid (don’t overfill),
engine
oil, axle lubricant, belt, cooling system and
brake system. Each of these is covered in this manual,
and the Index will help you find them quickly. If
you’re trailering, it’s a good idea to review these sections
before you start your trip.
Check periodically to see that all hitch nuts and bolts
are tight.
4-59

Trailer Wiring Harness
Your pickup is equipped with the eight-wire trailer
towing harness. This harness with a seven-pin universa
heavy-duty trailer connector is attached to a bracket
on the hitch platform.
The Center High-Mounted Stoplamp (CHMSL) wire is
tied next to the trailer wiring harness for use with a
trailer, slide-in camper or cap. The
eight-wire harness contains the following trailer
circuits:
Yellow: Left Stopnurn Signal
Dark Green: Right Stopnurn Signal
Brown: Taillamps
White: Ground
Light Green: Back-up Lamps
Light Blue: Center High-Mounted Stoplamp
(CHMSL)
Red: Battery Feed
Dark Blue: Trailer Brake
If your trailer
is equipped with electrical brakes, you can
get a jumper harnesdelectric trailer brake control
with a trailer battery feed fuse from your dealer. This
harness and fuse should be installed by your dealer or a
qualified service center.
If you need to tow a light-duty trailer with a standard
four-way round pin connector, you can also get an
adapter from your dealer.
4-60

Section 5 Service and Appearance Care
Service ............................................................ 5.3
Doing Your Own Service Work
......................... 5-4
Adding Equipment to the Outside
of Your Vehicle
........................................... 5-4
Fuel
................................................................ 5.5
Gasoline Octane
............................................ 5.5
Gasoline Specifications
.................................... 5.5
California Fuel
............................................... 5.6
Additives
....................................................... 5.6
Fuels in Foreign Countries
................. ....... 5.7
Filling Your Tank
......................................... 5-7
Filling a Portable Fuel Container
.................... 5-9
the Hood
............................................. 5.10
Hood Release
........................................ ,.5-10
Engine Compartment Overview
....................... 5.12
Checking
Things Under
Engine Oil
................................................... 5.13
Engine Air Cleaner/Filter
................................ 5.19
Engine Coolant
............................................. 5.24
Engine Overheating
....................................... 5.27
Cooling System
............................................ 5.30
Automatic
Transmission Fluid
........................ -5-21
Coolant Surge Tank Pressure Cap
.................. 5-27 Engine
Fan Noise
......................................... 5.36
Power Steering Fluid
..................................... 5.37
Windshield Washer Fluid
................................ 5-38
Brakes
........................................................ 5.39
Battery
........................................................ 5.42
Jump Starting
............................................... 5.43
All-Wheel Drive
......................... .............. 5-49
Rear Axle
....................................................... 5-50
Front Axle
...................................................... 5-51
Bulb Replacement
.......................................... 5-52
Halogen Bulbs
.............................................. 5-52
Headlamps
................................................. -5-52
Roof Marker Lamps
...................................... 5-54
Cargo Lamp
............................................. 5-56
Taillamps
..................................................... 5-58
Replacement Bulbs
....................................... 5-59
Front
Turn Signal, Sidemarker
and Daytime
Running Lamps
......................................... 5-53
Center High-Mounted Stoplamp (CHMSL) and
Pickup
Box Identification and Fender Marker
Lamps
..................................................... 5-58
Windshield Wiper Blade Replacement
.............. 5-60
5-
1

Checking Things Under
1-eH
od
Things ti.-- burn c2.. get on hot engine parts
and start a fire. These include liquids like fuel,
oil, coolant, brake fluid, windshield washer and
other fluids, and plastic or rubber. You or
others could be burned. Be careful not to drop or spill things that will burn onto a hot engine.
Hood Release
To open the hood do the following:
1. Pull the handle inside
the vehicle located
under and to the left
of
the steering wheel.
5-1 0

A. Engine Air CleanedFilter
B. Coolant Surge Tank
C. Air CleanerlFilter Restriction Indicator
B. Engine Oil Dipstick
E. Engine Oil Fill Cap
F. Automatic Transmission Dipstick
G. Fan
H. Remote Negative
(-) Terminal (GND)
I. Remote Positive (+) Terminal
J. Power Steering Fluid Reservoir
K. Brake Fluid Reservoir
L. Underhood Fuse Block
M. Battery
N. Windshield Washer Fluid Reservoir
Engine Oil
If the CHECK ENG OIL LEVEL message appears on
the instrument cluster, it means you need to check your
engine
oil level right away.
For more information, see “CHECK ENG
OIL LEVEL”
under
DIC Warnings and Messages on page 3-53.
You should check your engine oil level regularly; this is
an added reminder.
5-1 3

Get the vehicle warmed up by driving about 15 miles
(24 km) when outside temperatures are above
50°F
(1 OOC). If it's colder than 50°F (lO°C), drive the
vehicle
in THIRD (3) until the engine temperature
gage moves and then remains steady for 10 minutes.
A cold fluid check can be made after the vehicle has been
sitting for eight hours or more with the engine
off, but this
is used only as a reference. Let the engine run at idle for
five minutes
if outside temperatures are 50°F (1 0°C) or
more.
If it's colder than 50°F (1 OOC), you may have to idle
the engine longer. Should the fluid level be low during this
cold check, you
must check the fluid hot before adding
fluid. Checking the fluid hot will give you a more accurate
reading of the fluid level.
Checking the Fluid Level
Prepare your vehicle as follows:
Park your vehicle on a level place. Keep the engine
running.
With the parking brake applied, place the shift lever
in PARK (P).
With your foot on the brake pedal, move the shift
lever through each gear range, pausing for about
three seconds in each range. Then, position the shift
lever in PARK
(P).
Let the engine run at idle for three minutes or more. Then, without
shutting
off the engine, follow these steps:
The red transmission dipstick handle is located at the
rear of the engine compartment, on the passenger's
side. See
Engine Compartment Overview on page 5-12
for further information on location.
1. Flip the handle up and then pull out the dipstick
and wipe it with a clean rag or paper towel.
3. Push it back in all the way, wait three seconds and
then pull it back out again.
5-22

Brake Fluid
Your brake master cylinder reservoir is filled with DOT-3
brake fluid. See
Engine Compantment Overview on
page
5-12 for the location of the reservoir.
There are only two reasons why the brake fluid level
in the reservoir might go down. The first is that the brake
fluid goes down to an acceptable level during normal
brake lining wear. When new linings are put in, the fluid
level goes back
up. The other reason is that fluid is
leaking out of the brake system.
If it is, you should have
your brake system fixed, since a leak means that
sooner or later your brakes won’t work well, or won’t
work at all.
So, it isn’t a good idea to “top off your brake fluid.
Adding brake fluid won’t correct a leak.
If you add fluid
when your linings are worn, then you’ll have too much
fluid when you get new brake linings. You should add (or
remove) brake fluid, as necessary, only when work is
done
on the brake hydraulic system.
If yo, ..rave 1,- _._____ rake ---id, it ~~-1 spill on
the engine. The fluid will burn if the engine is
hot enough. You or others could be burned,
and your vehicle could be damaged. Add brake
fluid only when work is done on the brake
hydraulic system. See “Checking Brake Fluid”
in this section.
Refer to the Maintenance Schedule to determine when
to check your brake fluid. See
Part C: Periodic
Maintenance Inspections on page 6-14.
5-39

Checking Brake Fluid
You can check the brake fluid without taking off the cap.
What to Add
When you do need brake fluid, use only DOT-3 brake
fluid.
Use new brake fluid from a sealed container
only. See
Part Dr Recommended Fluids and Lubricants
on
page 6- 16.
Just look at the brake fluid reservoir. The fluid level
should be above
MIN. If it isn’t have your brake system
checked to see
if there is a leak. Always
clean the brake fluid reservoir cap and the area
around the cap before removing it. This will help
keep dirt from entering the reservoir.
With the wrong kind
of fluid in your brake
system, your brakes may not work well, or they
may not even work at all. This could cause a
crash. Always use the proper brake fluid.
After work is done on the brake hydraulic system,
make sure the level is above the MIN but not over the
MAX mark.
5-40

Notice:
Using the wrong fluid can badly damage brake
system parts. For example, just a few drops of
mineral-based
oil, such as engine oil, in your
brake system can damage brake system
parts
so badly that they’ll have to be replaced.
Don’t let someone
put in the wrong kind of fluid.
If you spill brake fluid on your vehicle’s painted
surfaces, the paint finish can be damaged.
Be careful not to spill brake fluid on your
vehicle.
If you do, wash it off immediately.
See “Appearance Care” in the Index.
Brake Wear
Your vehicle has four-wheel disc brakes.
Disc brake pads have built-in wear indicators that make
a high-pitched warning sound when the brake pads
are worn and new pads are needed. The sound
may come and go or be heard all the time your vehicle
is moving (except when you are pushing on the
brake pedal firmly). The
brake wear warning sound means that soon
your brakes won’t work well. That could lead to
an accident. When you hear the brake wear
Notice: Continuing to drive with worn-out brake
pads could result
in costly brake repair.
Some driving conditions or climates may cause a brake
squeal when the brakes are first applied or lightly applied.
This does not mean something is wrong with your brakes.
Properly torqued wheel nuts are necessary to help
prevent brake pulsation. When tires are rotated, inspect
brake pads for wear and evenly tighten wheel nuts in
the proper sequence
to GM torque specifications.
Brake linings should always be replaced as complete
axle sets.
See
Brake System Inspection on page 6- 15
5-41