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Tandem Axle ModelsItem
Number Item Remarks
1 Brake Camshafts One fitting each.
2 Propshaft U-JointOne fitting each
joint. Lubricate
with GM Part
No. 1051344, Wheel
Bearing Lubricant
3 Rear AxlesFill to level of
filler plug.
4Brake Shoe
Roller PinsApply engine oil
at pin to shoe joint
only.
5 Rear Spring PinOne fitting
each side.
Battery
Your vehicle has one or more maintenance free
batteries. When it is time for a new battery, be sure
it has the replacement number shown on the
original battery’s label. We recommend an
ACDelco
®replacement battery.
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.
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Page 328 of 430

How Often to Check
Wheel tightness is so important you should have a
technician check nut tightness on all wheels with a
torque wrench after your first 100 miles (160 km),
and then 1,000 miles (1 600 km) after that. Be sure
to repeat this service whenever you have a tire
removed or serviced. SeeScheduled Maintenance
on page 363for further information.
Wheel Replacement
Replace any wheel that is bent, cracked or badly
rusted or corroded. If wheel nuts keep coming
loose, replace the wheel. If the wheel leaks
air, replace it.
Your dealer will know the kind of wheel you need.
Each new wheel should have the same
load-carrying capacity, diameter, width, offset and
be mounted the same way as the one it replaces.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:
A leaking wheel could fail without warning.
A wheel designed for tubeless tires could
be leaking because it is damaged. Do not
use an inner tube or some other thing to try
to stop the leaking. Get a new wheel of the
proper type.
328
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 343 of 430
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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Page 346 of 430
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
Page 393 of 430

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 brakes.
Do not use the accelerator pedal, and be ready
to turn off the engine immediately if it starts.
3. On automatic transmission vehicles, try to
start the engine in each gear. The starter
should work only in PARK (P), if equipped,
or NEUTRAL (N). If the starter works in
any other position, your vehicle needs service.
On manual transmission vehicles, the starter
should work only when the clutch pedal is
all the way down.
Automatic Transmission Shift
Indicator Check
Check that the indicator points to the gear chosen.
Steering Check
Be alert for any changes in steering action,
abnormal front tire wear or steering wheel position.
An inspection or service is needed when the
steering wheel is harder to turn or has too much
free play, or if there are strange sounds when
turning or parking.
Brake System Check
Be alert to illumination of the low air warning lamp
or for the tone alarm, or changes in braking
action, such as repeated pulling to one side,
unusual sounds when braking or increased
brake pedal travel. Make sure air brake system
reservoirs are drained daily with full system
air pressure, and check system for leaks.
Any of these conditions could indicate the need
for brake system inspection and/or service.
393
Page 395 of 430

Lamps Check
Check panel lighting, warning lights, indicator
lights, and interior lamps. On the outside,
check: license plate lamps, sidemarker lamps,
reflectors or lights on outside mirrors, headlamps,
parking lamps, identification and clearance
lamps, taillamps, brake lamps, turn signals,
backup lamps, and hazard warning flashers.
Have headlamp aim checked at once if beams
seem improperly aimed.
Glass, Mirrors, Lamps and/or
Re ectors Condition Check
Look for broken, scratched, dirty, or damaged
glass, mirrors, lamps, or reflectors that could
reduce the view or visibility or cause injury.
Replace, clean or repair promptly.
Door Latches Check
Check that doors close, latch, and lock tightly.
Check for broken, damaged, or missing parts that
might prevent tight latching.
Hood Latches Check
Check that the hood closes firmly. Check for
broken, damaged, loose, or missing parts
that might prevent tight latching. Make sure the
secondary latch (if equipped) keeps the hood
from opening all the way when the primary latch
is released.
Fluid Leaks Check
Check for fuel, coolant, oil, or other fluid leaks by
looking at the surface beneath the vehicle after
it has been parked for awhile.
395
Page 417 of 430

A
Accessory Power Outlet(s).......................... 156
Adding a Snow Plow or Similar
Equipment................................................ 240
Adding Equipment to Your Airbag-Equipped
Vehicle....................................................... 81
Additives, Fuel............................................ 252
Add-On Electrical Equipment....................... 340
Air Cleaner/Filter, Engine............................. 280
Air Conditioning........................................... 157
Air Conditioning System.............................. 320
Air Pressure Gage...................................... 183
Air Shift Control........................................... 114
Air Suspension............................................ 129
Air Suspension Seats.................................... 13
Airbag
Off Light.................................................. 166
Readiness Light....................................... 165
Airbag Sensing and Diagnostic
Module (SDM).......................................... 409
Airbag System............................................... 68
Adding Equipment to Your
Airbag-Equipped Vehicle......................... 81
Airbag Off Switch....................................... 76
How Does an Airbag Restrain?.................. 73
Servicing Your Airbag-Equipped Vehicle..... 80Airbag System (cont.)
What Makes an Airbag Inflate?.................. 73
What Will You See After an Airbag
Inflates?................................................. 74
When Should an Airbag Inflate?................. 72
Where Are the Airbags?............................. 70
AM-FM Radio.............................................. 186
Antenna, Fixed Mast................................... 204
Anti-Lock Brake System (ABS).................... 212
Anti-Lock Brake, System Warning Light....... 172
Anti-Lock Brakes, Trailer System
Warning Light........................................... 172
Appearance Care
Aluminum or Chrome-Plated Wheels........ 337
Care of Safety Belts................................ 334
Chemical Paint Spotting........................... 338
Cleaning Exterior Lamps/Lenses.............. 335
Cleaning the Inside of Your Vehicle.......... 331
Fabric/Carpet........................................... 333
Finish Care.............................................. 335
Finish Damage......................................... 338
Instrument Panel, Vinyl, and Other
Plastic Surfaces.................................... 334
Sheet Metal Damage............................... 337
Tires........................................................ 337
Underbody Maintenance........................... 338
Vehicle Care/Appearance Materials.......... 339
417