2003 GMC ENVOY Brake system

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 ®rmly).
{CAUTION:
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 warning sound, have your vehicle
serviced.
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 ®rst 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 speci®cations.
Brake linings should always be replaced as complete
axle sets.
See
Brake System Inspection on page 6-17.
Brake Pedal Travel
See your dealer if the brake pedal does not return to
normal height, or if there is a rapid increase in
pedal travel. This could be a sign of brake trouble.
Brake Adjustment
Every time you make a brake stop, your disc brakes
adjust for wear.
5-40

Replacing Brake System Parts
The braking system on a vehicle is complex. Its many
parts have to be of top quality and work well together if
the vehicle is to have really good braking. Your
vehicle was designed and tested with top-quality GM
brake parts. When you replace parts of your braking
system Ð for example, when your brake linings
wear down and you need new ones put in Ð be sure
you get new approved GM replacement parts. If
you don't, your brakes may no longer work properly. For
example, if someone puts in brake linings that are
wrong for your vehicle, the balance between your front
and rear brakes can change Ð for the worse. The
braking performance you've come to expect can change
in many other ways if someone puts in the wrong
replacement brake parts.
Battery
Your new vehicle comes with a maintenance free
ACDelcožbattery. When it's time for a new battery, get
one that has the replacement number shown on the
original battery's label. We recommend an ACDelco
ž
battery. SeeEngine Compartment Overview on
page 5-12for battery location.
Warning:Battery posts, terminals and related
accessories contain lead and lead compounds,
chemicals known to the State of California to cause
cancer and reproductive harm. Wash hands after
handling.
5-41

Notice:Ignoring these steps could result in costly
damage to your vehicle that wouldn't be covered
by your warranty.
Trying to start your vehicle by pushing or pulling it
won't work, and it could damage your vehicle.
1. Check the other vehicle. It must have a 12-volt
battery with a negative ground system.
Notice:If the other system isn't a 12-volt system
with a negative ground, both vehicles can be
damaged.
2. Get the vehicles close enough so the jumper cables
can reach, but be sure the vehicles aren't touching
each other. If they are, it could cause a ground
connection you don't want. You wouldn't be able to
start your vehicle, and the bad grounding could
damage the electrical systems.
To avoid the possibility of the vehicles rolling, set
the parking brake ®rmly on both vehicles involved in
the jump start procedure. Put an automatic
transmission in PARK (P) or a manual transmission
in NEUTRAL before setting the parking brake. If
you have a four-wheel-drive vehicle, be sure
the transfer case is not in NEUTRAL.
Notice:If you leave your radio on, it could be badly
damaged. The repairs wouldn't be covered by
your warranty.
3. Turn off the ignition on both vehicles. Unplug
unnecessary accessories plugged into the cigarette
lighter or accessory power outlets (if equipped).
Turn off the radio and all lamps that aren't needed.
This will avoid sparks and help to save both
batteries. And it could save your radio!
4. Open both hoods and locate the batteries. Find the
positive (+) and negative (-) terminals on each
battery. Your vehicle has a remote negative (-) jump
starting terminal. You should always use this
remote terminal instead of the terminal on the
battery. The remote negative (-) terminal is located
on the front engine lift bracket on vehicles with
the L6 engine or the engine accessory drive bracket
for vehicles with the V8 engine, and is marked
ªGND.º See
Engine Compartment Overview
on page 5-12for more information on location.
5-43

Tire Chains
{CAUTION:
Don't use tire chains. There's not enough
clearance. Tire chains used on a vehicle without
the proper amount of clearance can cause
damage to the brakes, suspension or other
vehicle parts. The area damaged by the tire
chains could cause you to lose control of your
vehicle and you or others may be injured in a
crash. Use another type of traction device only
if its manufacturer recommends it for use on
your vehicle and tire size combination and road
conditions. Follow that manufacturer's
instructions. To help avoid damage to your
vehicle, drive slowly, readjust or remove the
device if it's contacting your vehicle, and don't
spin your wheels. If you do ®nd traction devices
that will ®t, install them on the rear tires.
Accessory In¯ator
Your vehicle may be equipped with an air in¯ator
system. You can in¯ate things like basketballs and
bicycle tires. Also, you can use it to bring your tire
pressure up to the proper pressure. It is not designed to
in¯ate large objects which will require more than ®ve
minutes to in¯ate, such as an air mattress.
The air in¯ator is often
located in the rear
compartment on the
passenger's side of the
vehicle behind an
access cover.
To remove the cover, pull the two tabs on the cover and
pull it off.
5-62

Fuses Usage
1Electrically-Controlled Air
Suspension
2Passenger's Side High-Beam
Headlamp
3Passenger's Side Low-Beam
Headlamp
4 Back-Up-Trailer Lamps
5 Driver's Side High-Beam Headlamp
6 Driver's Side Low-Beam Headlamp
7 Wash
8 Automatic Transfer Case
9 Windshield Wipers
10 Powertrain Control Module B
11 Fog Lamps
12 Stop Lamp
13 Cigarette Lighter
14 Ignition Coils
15 Air Suspension Ride
16 TBD-Ignition 1Fuses Usage
17 Crank
18 Air Bag
19 Electric Brake
20 Cooling Fan
21 Horn
22 Ignition E
23 Electronic Throttle Control
24Instrument Panel Cluster, Driver
Information Center
25 Automatic Shift Lock Control System
26 Engine 1
27 Back-Up
28 Powertrain Control Module 1
29 Oxygen Sensor
30 Air Conditioning
31 Truck Body Controller
32 Trailer
33 Anti-Lock Brakes (ABS)
5-93

Fuses Usage
1Electrically-Controlled Air
Suspension
2Passenger's Side High-Beam
Headlamp
3Passenger's Side Low-Beam
Headlamp
4 Back-Up-Trailer Lamps
5 Driver's Side High-Beam Headlamp
6 Driver's Side Low-Beam Headlamp
7 Wash
8 Automatic Transfer Case
9 Windshield Wipers
10 Powertrain Control Module B
11 Fog Lamps
12 Stop Lamp
13 Cigarette Lighter
14 Ignition Coils
15 Cannister Vent
16 TBD-Ignition 1
17 Crank
18 Air Bag
19 Electric Brake
20 Cooling Fan
21 HornFuses Usage
22 Ignition E
23 Electronic Throttle Control
24Instrument Panel Cluster, Driver
Information Center
25 Automatic Shift Lock Control System
26 Engine 1
27 Back-Up
28 Powertrain Control Module 1
30 Air Conditioning
31 Truck Body Controller 1
32 Trailer
33 Anti-Lock Brakes (ABS)
34 Ignition A
35 Blower Motor
36 Ignition B
50 Passenger's Side Trailer Turn
51 Driver's Side Trailer Turn
52 Hazard Flashers
53 Oxygen Sensor Bank A
54 Oxygen Sensor Bank B
55 Injector Bank A
56 Injector Bank B
Relays Usage
37 Headlamp Washer
5-96

Fuses Usage
23 Blank
24 Unlock
25 Blank
26 Blank
27 OH Battery/OnStar
žSystem
29 RainsenseŸ Wipers
30 Parking Lamps
31Truck Body Controller 4 Cruise
Control
32 Truck Body Controller 5
33 Front Wipers
34 Vehicle Stop
35 Blank
36 Heat Ventilation Air Conditioning B
37 Front Parking Lamps
38 Left Turn Signal
Fuses Usage
39 Heat Ventilation Air Conditioning 1
40 Truck Body Controller 4
41 Radio
42 Trailer Park
43 Right Turn Signal
44 Heat Ventilation Air Conditioning
45 Rear Fog Lamps
46 Auxiliary Power 1
47 Ignition 0
48 Four-Wheel Drive
49 Blank
50 Truck Body Controller Ignition
51 Brakes
52 Truck Body Controller Run
5-99

Fuses Usage
22 Retained Accessory Power
23 Blank
24 Unlock
25 Blank
26 Blank
27 OH Battery/OnStar
žSystem
28 Sunroof
29 RainsenseŸ Wipers
30 Parking Lamps
31Truck Body Controller 4 Cruise
Control
32 Truck Body Controller 5
33 Front Wipers
34 Vehicle Stop
35 Blank
36 Heat Ventilation Air Conditioning B
37 Front Parking Lamps
Fuses Usage
38 Left Turn Signal
39 Heat Ventilation Air Conditioning 1
40 Truck Body Controller 4
41 Radio
42 Trailer Park
43 Right Turn Signal
44 Heat Ventilation Air Conditioning
45 Rear Fog Lamps
46 Auxiliary Power 1
47 Ignition 0
48 Four-Wheel Drive
49 Blank
50 Truck Body Controller Ignition
51 Brakes
52 Truck Body Controller Run
5-101