
Low Coolant Warning Light............................3-35
Wait to Start Light........................................3-35
Malfunction Indicator Lamp.............................3-36
Oil Pressure Gage........................................3-38
Low Oil Level Light.......................................3-39
Change Engine Oil Light................................3-39
Engine Overspeed Warning Light....................3-40
Engine Shutdown Warning Light.....................3-40
Transmission Temperature Gage.....................3-40
Exhaust Brake Indicator Light.........................3-41
Differential Lock Indicator Light.......................3-41
Reduced Engine Power Light.........................3-42
Highbeam On Light.......................................3-42
Daytime Running Lamps (DRL)
Indicator Light...........................................3-42
Low Washer Fluid Warning Light.....................3-43
Power Take-Off Light (PTO)...........................3-43Check Gages Warning Light...........................3-43
Fuel Gage...................................................3-44
Water in Fuel Warning Light...........................3-45
Change Fuel Filter Warning Light....................3-45
Diesel Particulate Filter Warning Light..............3-46
Air Filter Restriction Indicator..........................3-46
Air Pressure Gage........................................3-47
Hourmeter Gage...........................................3-47
Audio System(s).............................................3-48
Setting the Clock..........................................3-48
Radio(s)......................................................3-49
Theft-Deterrent Feature..................................3-57
Radio Reception...........................................3-58
Fixed Mast Antenna......................................3-58
Chime Level Adjustment................................3-58
Section 3 Instrument Panel
3-2

Instrument Panel SwitchbankThis switchbank is located in the center of the instrument
panel.
e:Marker Lamps on page 3-16.
g/j:Power Take-Off (PTO) on page 2-30and
High Idle System on page 2-20.
i:Traction Control System (TCS) on page 4-8.
f:Outside Heated Mirrors on page 2-52.
L:Diesel Particulate Filter on page 2-46.
h:Rear Air Suspension Dump Control Switch.
SeeAir Suspension on page 2-44.
k:Rear Axle Shift Control Switch. SeeTwo-Speed
Rear Axle on page 2-36.
q:Diesel Engine Exhaust Brake on page 2-26.
l:Differential Lock Control Switch. SeeRear Axle
Differential Lock Control on page 4-7.
c:Airbag Off Switch on page 1-55.
If the vehicle does not have some of the features
controlled by these switches, a blank switch marker
is in its place.
3-18

Exhaust Brake Indicator Light
For vehicles with an
exhaust brake, this light is
located above the
climate controls.
The exhaust brake indicator light will come on and stay
on whenever the diesel engine exhaust brake or
exhaust restrictor is active. For more information, see
Diesel Engine Exhaust Brake on page 2-26andExhaust
Restrictor (Engine Warm-Up) on page 2-22.
Differential Lock Indicator Light
If your vehicle has
this feature, this light is
located in the center of
the instrument panel.
The light is on when
the rear differential lock
system is in use.
The light will come on momentarily during starting. If the
light fails to come on, have it repaired as soon as possible
so you will be aware when the lock system is in use.
SeeRear Axle Differential Lock Control on page 4-7for
more information.
3-41

Your Driving, the Road, and the Vehicle............4-2
Driving for Better Fuel Economy.......................4-2
Defensive Driving...........................................4-2
Drunk Driving.................................................4-3
Control of a Vehicle........................................4-3
Braking.........................................................4-4
Hydraulic Brake Systems.................................4-4
Antilock Brake System (ABS)...........................4-5
Braking in Emergencies...................................4-5
Trailer Brake Hand Control Valve......................4-6
Rear Axle Differential Lock Control....................4-7
Traction Control System (TCS).........................4-8
Steering........................................................4-9
Off-Road Recovery.......................................4-11
Passing.......................................................4-11Loss of Control.............................................4-12
Driving at Night............................................4-13
Driving in Rain and on Wet Roads..................4-14
Highway Hypnosis........................................4-15
Hill and Mountain Roads................................4-16
Winter Driving..............................................4-17
If Your Vehicle is Stuck in Sand, Mud,
Ice, or Snow.............................................4-19
Rocking Your Vehicle to Get It Out.................4-19
Tow Hooks..................................................4-20
Loading the Vehicle......................................4-20
Adding a Snow Plow or Similar Equipment.......4-22
Towing..........................................................4-23
Towing Your Vehicle.....................................4-23
Trailer Connections.......................................4-25
Section 4 Driving Your Vehicle
4-1

Rear Axle Differential Lock Control
If the vehicle has a
controlled traction or
locking differential axle, the
switch is located in the
center of the instrument
panel.
This control is on single rear axle vehicles.
If approaching a slippery surface where one or both
wheels may start to slip, press the switch to off. The rear
differential locks so power is transmitted equally to
both rear wheels.
Let up on the accelerator before turning on the rear axle
differential lock.Notice:Turning on the inter-axle differential lock
while the rear wheels are spinning freely, as
they might on snow or ice, can damage the axle(s).
Turn on this control only while the wheels are
not spinning freely.
Interaxle Differential Lock
This switch is located on
the center instrument
panel. This control is on
tandem rear axle vehicles.
Press the switch to engage/lock the tandem front axle
differential to the rear axle differential. This driver
controlled feature improves traction over slippery or
uneven surfaces.
4-7

Rear Axle Shift Motor
When to Check and Change Fluid
If you have an optional air-shift two-speed, controlled
traction, or locking differential type rear axle, a good time
to check the fluid level in the axle shift motor is when
the rear axle lubricant is checked.
How to Check Fluid
Remove the plug on the front plate of the axle shift
motor, add enough fluid to raise the level to the bottom
of the filler plug hole, then replace the plug.
What to Use
Refer to your Maintenance Schedule to determine what
kind of lubricant to use. SeePart C: Recommended
Fluids and Lubricants on page 6-31.
Four-Wheel Drive
Transfer Case
When to Check Lubricant
It is not necessary to regularly check transfer case fluid
unless you suspect there is a leak or you hear an
unusual noise. A fluid loss could indicate a problem.
Have it inspected and repaired.
How to Check Lubricant
A. Fill Plug
B. Drain Plug
To get an accurate reading, the vehicle should be on a
level surface.
If the level is below the bottom of the fill plug hole,
located on the transfer case, you’ll need to add some
lubricant. Add enough lubricant to raise the level to
the bottom of the fill plug hole. Use care not to
overtighten the plug.
5-68

If your vehicle has four-wheel drive, the axle differentials,
propshafts, and transfer case may be damaged if tires
of different sizes, brands or tread types are installed
on the front and rear axles. That damage would not be
covered under your warranty.
Buying New Tires
GM has developed and matched specific tires for your
vehicle. If you need replacement tires, GM strongly
recommends that you get tires that are the same size,
brand, load range, speed rating, and construction type
(radial and bias-belted tires) as your vehicle’s original
tires. This way, your vehicle will continue to have tires
that are designed to give the same performance and
vehicle safety, during normal use, as the original tires.
GM recommends replacing tires in sets of six or eight as
applicable. This is because uniform tread depth on all
tires will help keep your vehicle performing most like it did
when the tires were new. Replacing less than a full set of
tires can affect the braking and handling performance of
your vehicle.
{CAUTION:
Mixing tires could cause you to lose control
while driving. If you mix tires of different
sizes, brands, or types (radial and bias-belted
tires) the vehicle may not handle properly,
and you could have a crash. Using tires of
different sizes, brands, or types may also
cause damage to your vehicle. Be sure to
use the correct size, brand, and type of tires
on your vehicle’s wheels.
{CAUTION:
If you use bias-ply tires on the vehicle, the
wheel rim flanges could develop cracks after
many miles of driving. A tire and/or wheel
could fail suddenly, causing a crash. Use
only radial-ply tires with the wheels on the
vehicle.
5-79

Diesel Engine.................................................2-26
Engine Alarm and Automatic Shutdown...........2-18
Exhaust Restrictor.......................................2-22
Fuel............................................................ 5-8
High Idle System.........................................2-20
Starting......................................................2-14
Diesel Particulate Filter....................................2-46
Diesel Particulate Filter Warning Light................3-46
Differential Lock Control, Rear Axle..................... 4-7
Differential Lock Indicator Light.........................3-41
Doing Your Own Service Work........................... 5-5
Dome Lamps .................................................3-16
Door
Locks.......................................................... 2-6
Power Door Locks......................................... 2-7
Driving
At Night.....................................................4-13
Defensive..................................................... 4-2
Drunken....................................................... 4-3
Highway Hypnosis.......................................4-15
Hill and Mountain Roads..............................4-16
In Rain and on Wet Roads...........................4-14
Rocking Your Vehicle to Get it Out.................4-19
Tow Hooks.................................................4-20
Winter........................................................4-17
Driving for Better Fuel Economy......................... 4-2
Dual Tire Operation.........................................5-78E
EDR .............................................................7-11
Electrical System
Add-On Equipment......................................5-95
Fuses and Circuit Breakers...........................5-96
Fusible Links..............................................5-95
Headlamp Wiring.........................................5-95
Instrument Panel Fuse Block.........................5-96
Power Windows and Other Power Options......5-96
Underhood Fuse Block.................................5-99
Windshield Wiper Fuses...............................5-95
Engine
Air Cleaner/Filter.........................................5-38
Alarm and Automatic Shutdown.....................2-18
Change Engine Oil Light...............................3-39
Check and Service Engine Soon Lamp...........3-36
Checks Before Operating..............................2-23
Coolant......................................................5-47
Coolant Heater............................................2-25
Coolant Temperature Gage...........................3-34
Diesel Engine Exhaust Brake........................2-26
Drive Belt Routing......................................5-110
Exhaust.....................................................2-45
Exhaust Restrictor.......................................2-22
Fan Breakage............................................... 5-6
Fan Noise..................................................5-49
High Idle System.........................................2-20
Oil ....................................5-24, 5-27, 5-28, 5-32
Oil Life System...........................5-35, 5-36, 5-38
4