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If you need to replace any of your wheels, wheel bolts
or wheel nuts, replace them only with new GM
original equipment parts. This way, you will be sure to
have the right wheel, wheel bolts and wheel nuts
for your vehicle.
{CAUTION:
Using the wrong replacement wheels, wheel
bolts or wheel nuts on your vehicle can be
dangerous. It could affect the braking and
handling of your vehicle, make your tires lose
air and make you lose control. You could have
a collision in which you or others could be
injured. Always use the correct wheel, wheel
bolts and wheel nuts for replacement.
Notice:The wrong wheel can also cause problems
with bearing life, brake cooling, speedometer or
odometer calibration, headlamp aim, bumper height,
vehicle ground clearance and tire or tire chain
clearance to the body and chassis.
SeeChanging a Flat Tire on page 5-75for more
information.
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 412 of 496

Tire Chains
{CAUTION:
If your vehicle is a 1500 Series, don’t use tire
chains. They can damage your vehicle because
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.Notice:If your vehicle is a 2500 Series, use tire
chains only where legal and only when you must.
Use chains that are the proper size for your
tires. Install them on the tires of the rear axle. Don’t
use chains on the tires of the front axle. Tighten
them as tightly as possible with the ends securely
fastened. Drive slowly and follow the chain
manufacturer’s instructions. If you can hear the
chains contacting your vehicle, stop and retighten
them. If the contact continues, slow down until
it stops. Driving too fast or spinning the wheels with
chains on will damage your vehicle.
If a Tire Goes Flat
It is unusual for a tire to blowout while you’re 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 at tire will create a drag that
pulls the vehicle toward that side. Take your foot off the
accelerator pedal and grip the steering wheel rmly.
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
5-74
Page 413 of 496

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.
{CAUTION:
Lifting a vehicle and getting under it to do
maintenance or repairs is dangerous without
the appropriate safety equipment and training.
The jack provided with your vehicle is
designed only for changing a at tire. If it is
used for anything else, you or others could be
badly injured or killed if the vehicle slips off
the jack. Use the jack provided with your
vehicle only for changing a at tire.
If a tire goes at, the next part shows how to use your
jacking equipment to change a at tire safely.
Changing a Flat Tire
If a tire goes at, avoid further tire and wheel damage
by driving slowly to a level place. Turn on your
hazard warning ashers.
{CAUTION:
Changing a tire can be dangerous. The vehicle
can slip off the jack and roll over or fall on you
or other people. You and they could be badly
injured or even killed. Find a level place to
change your tire. To help prevent the vehicle
from moving:
1. Set the parking brake rmly.
2. Put the shift lever in PARK (P).
3. If you have a four-wheel-drive vehicle,
be sure the transfer case is in a drive
gear— not in NEUTRAL.
4. Turn off the engine and do not restart
while the vehicle is raised.
5. Do not allow passengers to remain in the
vehicle.
6. Put the wheel blocks at the front and rear
of the tire farthest away from the one
being changed. That would be the tire on
the other side, at the opposite end of the
vehicle.
5-75
Page 424 of 496
9. Turn the wheel wrench counterclockwise to lower
the vehicle. Lower the jack completely.
{CAUTION:
Incorrect wheel nuts or improperly tightened
wheel nuts can cause the wheel to come loose
and even come off. This could lead to an
accident. Be sure to use the correct wheel
nuts. If you have to replace them, be sure to
get new GM original equipment wheel nuts.
Stop somewhere as soon as you can and have
the nuts tightened with a torque wrench to the
proper torque speci cation. SeeCapacities
and Specifications on page 5-112for wheel nut
torque speci cation.
Notice:Improperly tightened wheel nuts can lead
to brake pulsation and rotor damage. To avoid
expensive brake repairs, evenly tighten the wheel
nuts in the proper sequence and to the proper
torque speci cation. SeeCapacities and
Specifications on page 5-112for the wheel nut
torque speci cation. Rear Position — 1500
Series
Rear Position — 2500
Series
5-86
Page 443 of 496
Fuses Usage
RR Wiper Rear Window Wiper Switch
SEO ACCYSpecial Equipment Option
Accessory
WS WPR Windshield Wipers
TBC ACCYTruck Body Controller
Accessory
Fuses Usage
IGN 3 Ignition, Heated Seats
4WD Four-Wheel Drive System
HTR A/C Climate Control System
LOCKPower Door Lock Relay
(Lock Function)
HVAC 1Inside Rearview Mirror,
Climate Control System
L DOORDriver’s Door Harness
Connection
CRUISE Cruise Control
UNLOCKPower Door Lock Relay
(Unlock Function)
RR FOG LP Rear Fog Lamp (Export Only)
BRAKE Anti-Lock Brake System
DRIVER UNLOCKPower Door Lock Relay
(Driver’s Door Unlock
Function)
IGN 0 PCM, TCM
TBC IGN 0 Truck Body Controller
VEH CHMSLVehicle and Trailer High
Mounted Stoplamp
5-105
Page 444 of 496
Fuses Usage
LT TRLR ST/TRN Left Turn Signal/Stop Trailer
LT TRNLeft Turn Signals and
Sidemarkers
VEH STOPVehicle Stoplamps, Brake
Module, Electronic Throttle
Control Module
Body Harness Connector
RT TRLR ST/TRN Right Turn Signal/Stop Trailer
RT TRNRight Turn Signals and
Sidemarkers
DDM Driver Door Module
AUX PWR 2Rear Cargo Area Power
Outlets
LOCKS Power Door Lock System
ECCRear Electronic Climate
Control, Liftgate
TBC 2C Truck Body Controller
FLASH Flasher Module
CB LT DOORSLeft Power Window Circuit
Breaker
TBC 2B Truck Body Controller
TBC 2A Truck Body ControllerCenter Instrument Panel Fuse Block
The center instrument panel utility block is located
underneath the instrument panel, to the left of the
steering column.
Device Usage
SEOSpecial Equipment
Option/Off-road Lamps
Harness Connector
TRAILER Trailer Brake Wiring
UPFIT Up tter (Not Used)
5-106
Page 447 of 496

*1— Gasoline Engine and Fuel Injection Rail #2.
*2— Gasoline Engine and Fuel Injection Rail #1.
*3— Gasoline Engine; Oxygen Sensors.
*4— Gasoline Engine; Oxygen Sensors.
*5— PCM Ignition
Fuses Usage
GLOW PLUG Not Used
CUST FEED Accessory Power
HYBRID Not Used
STUD #1 Auxiliary Power
MBECMid Bussed Electrical Center
Power Feed, Front Seats,
Right Doors
BLOWER Front Climate Control Fan
LBECLeft Bussed Electrical Center,
Door Modules, Door Locks,
Auxiliary Power
Outlet — Rear Cargo Area
and Instrument Panel
STUD 2Accessory Power/Trailer
Wiring Brake Feed
ABS Anti-Lock Brakes
VSES/ECAS Vehicle Stability
IGN A Ignition Power
IGN B Ignition Power
Fuses Usage
LBEC 1Left Bussed Electrical Center,
Left Doors, Truck Body
Controller, Flasher Module
TRL PARK Parking Lamps Trailer Wiring
RR PARKRight Rear Parking and
Sidemarker Lamps
LR PARKLeft Rear Parking and
Sidemarker Lamps
PARK LP Parking Lamps Relay
STRTR Starter Relay
INTPARK Interior Lamps
STOP LP Stoplamps
TBC BATTTruck Body Controller Battery
Feed
S/ROOF Sunroof
SEO B2 Off-Road Lamps
4WSVent Solenoid
Canister/Quadrasteer Module
Power (If Equipped)
RR HVAC Rear Climate Control
AUX PWRAuxiliary Power
Outlet — Console
IGN 1 Ignition Relay
PCM 1 Powertrain Control Module
ETC/ECMElectronic Throttle Control,
Electronic Brake Controller
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Page 449 of 496
Fuses Usage
LO HDLP-LTDriver’s Side Headlamp Low
Beam
BTSIBrake Transmission Shift
Interlock System
CRNK Starting System
LO HDLP-RTPassenger’s Side Headlamp
Low Beam
FOG LP Fog Lamp Relay
FOG LP Fog Lamps
HORN Horn Relay
W/S WASH Not Used
W/S WASH Not Used
INFOOnStar
®/Rear Seat
Entertainment
RADIO AMP Radio Ampli er
RH HIDRight Hand High Intensity
Discharge Lamp
HORN Horn Fuse
EAP Electric Adjustable Pedals
TRECAll-Wheel Drive Module (If
Equipped)
SBA Supplemental Brake Assist
Auxiliary Electric Cooling Fan Fuse
Block
The auxiliary electric
cooling fan fuse block is
located in the engine
compartment on the
driver’s side of the vehicle
next to the underhood
fuse block.
Lift the cover for access to the fuse/relay block.
Fuses Usage
COOL/FAN Cooling Fan
COOL/FAN Cooling Fan Relay Fuse
COOL/FAN Cooling Fan Fuse
Relays Usage
COOL/FAN 1 Cooling Fan Relay 1
COOL/FAN 3 Cooling Fan Relay 3
COOL/FAN 2 Cooling Fan Relay 2
5-111