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Notice:Ignoring these steps could result in
costly damage to your vehicle that would
not be covered by your warranty.
Trying to start your vehicle by pushing or
pulling it will not work, and it could damage
your vehicle.
1. Check the other vehicle. It must have a
12-volt battery (or batteries) with a negative
ground system.
Notice:If the other vehicle’s system is not a
12-volt system with a negative ground,
both vehicles can be damaged. Only use
vehicles with 12-volt systems with negative
grounds to jump start your vehicle.
If you have a diesel engine vehicle with
two batteries (or more), you should know
before you begin that, especially in cold
weather, you may not be able to get enough
power from a single battery in another
vehicle to start your diesel engine.
If your vehicle has more than one battery, use
the one closest to the starter — this will
reduce electrical resistance.2. Get the vehicles close enough so the jumper
cables can reach, but be sure the vehicles are
not touching each other. If they are, it could
cause a ground connection you do not
want. You would not 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 firmly 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 in a drive gear, not in NEUTRAL.
Notice:If you leave your radio or other
accessories on during the jump starting
procedure, they could be damaged. The repairs
would not be covered by your warranty.
Always turn off your radio and other
accessories when jump starting your vehicle.
3. Turn off the ignition on both vehicles. Unplug
unnecessary accessories plugged into the
cigarette lighter or accessory power outlets.
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Page 329 of 430

{CAUTION:
Without the correct wheel, you may not be
able to stop properly, and you could have
other problems like a tire air-out. You
could have a collision. If you do not go to
your dealer to get a new wheel, be sure
you get the correct one. Each new wheel
should match the original wheel in
load-carrying capacity, in ation pressure
capacity, diameter, width, offset and
mounting con guration.
Using wheels and tires with higher load-carrying
limits than the original wheels and tires does
not change the Gross Axle Weight Rating (GAWR)
or the Gross Vehicle Weight Rating (GVWR) of
your vehicle. SeeLoading Your Vehicle on
page 238for more information.Notice:The wrong wheel can cause trouble in
bearing life, brake cooling,
speedometer/odometer calibration, headlamp
aim, bumper height, vehicle ground clearance,
stopping distance and tire clearance to the
body and chassis. You could also have other
problems like a tire air-out.
Used Replacement Wheels
{CAUTION:
Putting a used wheel on your vehicle is
dangerous. You cannot know how it has
been used or how far it has been driven. It
could fail suddenly and cause a crash. If
you have to replace a wheel, use a new
GM original equipment wheel.
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Page 330 of 430

If a Tire Goes Flat
It is unusual for a tire to blowout while you are
driving, especially if you maintain your tires
properly. If air goes out of a tire, it is much more
likely to leak out slowly. But if you should ever
have a blowout, here are a few tips about what to
expect and what to do:
If a front tire fails, the flat tire will create a drag
that pulls the vehicle toward that side. Take your
foot off the accelerator pedal and grip the
steering wheel firmly. Steer to maintain lane
position, and then gently brake to a stop well out
of the traffic lane.
A rear blowout, particularly on a curve, acts much
like a skid and may require the same correction
you would use in a skid. In any rear blowout,
remove your foot from the accelerator pedal. Get
the vehicle under control by steering the way
you want the vehicle to go. It may be very bumpy
and noisy, but you can still steer. Gently brake
to a stop –– well off the road if possible.If a tire goes flat, avoid further tire and wheel
damage by driving slowly to a level place and turn
on your hazard warning flashers. SeeHazard
Warning Flashers on page 142.
{CAUTION:
Your vehicle, when new, did not include
tire changing equipment or a place to
store a tire in the vehicle. Special tools
and procedures are required if a tire
needs to be serviced. If these tools and
procedures are not used, you or others
could be injured or killed while trying to
change or service a truck tire.
330
Page 341 of 430

Headlamp Wiring
The headlamp wiring is protected by a circuit
breaker in the light switch. An electrical overload
will cause the lights to go on and off, or in
some cases to remain off. If this happens, have
your headlamp wiring checked right away.
Windshield Wiper Fuses
The windshield wiper motor is protected by a
circuit breaker inside the motor and a circuit
breaker or fuse in the fuse block. If the motor
overheats, the wipers will stop until the motor
cools. If the overload is caused by an electrical
problem, be sure to get it fixed.
Fusible Links
A fusible link is a short piece of wire several gauge
sizes smaller than the circuit it protects. It will melt
in an overload situation, opening the circuit.
Your starter and other circuits have these fusible
links. The size is printed on the insulation. If the
insulation is burned beyond recognition, consult
your dealer for the proper size. Replace a fusiblelink with one of the same size and insulation type.
Fusible link insulation is a special purpose
high-temperature material.
Some examples of circuits with fusible links are
the hydraulic brake booster motor feed circuit, the
generator output circuit, and the intake heater
feed circuit in vehicles with a diesel engine.
Power Windows and Other
Power Options
Circuit breakers in the fuse panel protect the power
windows and other power accessories. When the
current load is too heavy, the circuit breaker opens.
This protects the circuit until the current load returns
to normal or the problem is fixed.
Fuses and Circuit Breakers
The wiring circuits in your vehicle are protected
from short circuits by a combination of fuses, circuit
breakers, maxi-fuses and fusible links. This greatly
reduces the chance of a fire caused by an electrical
problem. There may be a fuse taped to the wiring
harness near the hydraulic brake booster.
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Fuse Usage
7 Hazard Warning Flashers
8 Power Post
9 Courtesy Lamps
10 Warning Lights, Gages and Indicators
11 Starter
12 Rear Axle/Four-Wheel-Drive
13Trailer Turn Signals/Hazard Warning
Flashers
14 Radio/Chime
15 Daytime Running Lamps
16 Airbag System
17 Exterior/Interior Lamps
18 Parking Brake
19 Accessory Power
20 Ignition 4
21 Sidemarker Lamps
22 Turn Signal/Backup Lamps
23 TransmissionFuse Usage
24 Hydraulics/Air Brake
A Spare
B Spare
Fuse Usage
Blank Not Used
BRK Brake Warning Lamp
RT PRK Passenger’s Side Parking Lamps
Blank Not Used
Blank Not Used
LT PARK Driver’s Side Parking Lamps
RT REAR
TRN/STOPPassenger’s Side Rear Turn
Signal/Stoplamp
LT REAR
TRN/STOPDriver’s Side Rear Turn
Signal/Stoplamp
RADIO Radio
Blank Not Used
Blank Not Used
PWR WNDW Power Windows
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Relay Usage
ECU/PTO*Engine Control Unit/Power Take-Off
*Diesel 7.8 DURAMAX
®
BRK LAMPC4/C5 Brake Lamps,
C6/C7/C8 Tractor/Trailer Wiring
DRL Daytime Running Lamps
IGN-4 Ignition
CHMSL Center High Mounted Stoplamp
MRK LTS Sidemarker and Clearance Lamps
HTD/MIRR Heated Mirrors
HTR Diesel Heated Fuel
RT TRN TRLR Passenger’s Side Trailer Turn Signal
Blank Not Used
LT TRN TRLR Driver’s Side Trailer Turn Signal
Blank Not Used
Blank Not Used
Blank Not Used
Underhood Fuse Block
When a circuit goes out, the problem could be in
either the primary or secondary underhood
fuse blocks. These blocks use blade-type fuses.
Both underhood fuse blocks are located in
the engine compartment, on the passenger’s side
of the vehicle.
To access the fuse blocks, gently squeeze both
sides of the cover to unlatch the tabs at the
top. Then, unsnap both attachments at the bottom
and remove the cover.
Be sure to replace fuses with fuses of the same
rating. Do not use fuses of higher amperage
than those indicated on the fuse block.
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Fuse Usage
RR DEFOG Rear Defogger
ENG 1 Engine 1
ENG 3 Engine 3
PCM-B Powertrain Control Module
Fuse Usage
BLANK Not Used
ENG 4 Engine 4
ENG 2 Engine 2
HTD FUEL Heated Fuel
BLANK Not Used
BLANK Not Used
02A Emissions
A/C COMP Air Conditioning Compressor
ABS 1 Anti-lock Brake System 1
ABS 2 Anti-lock Brake System 2
ABS 3 Anti-lock Brake System 3
ENGINE Engine
E/A PUMP Electronic/Automatic Pump
HORN Horn
NOTE 2L18 Fuel, LG4 Powertrain Control
Valve, LG5 Electronic Control
Module Primary Underhood Fuse Block
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Fuse Usage
NOTE 3L18 Fuel, LG4 Powertrain Control
Valve, LG5 Electronic Control
Module
STUD A Spare
STUD B Spare
Relay Usage
NOTE 1LLY/L18 Fuel Pump Relay, LG4/LG5
Heated Fuel Relay
IGN B Ignition Relay
STARTER Starter Relay
HORN Horn Relay
IGN A Ignition Relay
PTO/ECU*Power Take-Off/Engine Control Unit
(*Diesel 7.8L LG4)
REVERSE Reverse Relay
NEUTRAL
STARTNeutral Start (LG4 Allison Automatic
Transmission Series 3000/3500)
Fuse Usage
IGN 1 Ignition 1
IGN 4 Ignition 4
IGN 3 Ignition 3
BATT/HAZ Battery/Hazard Warning Flashers
HEADLAMP Headlamps
LIGHTING Interior/Exterior Lamps
HVAC Climate Control System
NOTEC4/C5 Electric Brake,
C6/C7/C8 Brake Lamps Secondary Underhood
Fuse Block
346