
Rear Heating System
If your vehicle has a rear
heater, the thumbwheel for
this feature is located on
the headliner.
To increase and decrease the flow of heated air to
the rear floor vents, turn the thumbwheel to the
desired fan speed. To turn the fan off, turn the
thumbwheel down.
Warning Lights, Gages, and
Indicators
This part describes the warning lights and gages that
may be on your vehicle. The pictures will help you
locate them.Warning lights and gages can signal that something is
wrong before it becomes serious enough to cause
an expensive repair or replacement. Paying attention to
your warning lights and gages could also save you
or others from injury.
Warning lights come on when there may be or is a
problem with one of your vehicle’s functions. As you will
see in the details on the next few pages, some
warning lights come on briefly when you start the
engine just to let you know they’re working. If you are
familiar with this section, you should not be alarmed
when this happens.
Gages can indicate when there may be or is a problem
with one of your vehicle’s functions. Often gages
and warning lights work together to let you know when
there’s a problem with your vehicle.
When one of the warning lights comes on and stays on
when you are driving, or when one of the gages shows
there may be a problem, check the section that tells you
what to do about it. Please follow this manual’s advice.
Waiting to do repairs can be costly – and even
dangerous. So please get to know your warning lights
and gages. They’re a big help.
3-23

Low Coolant Warning Light
You have a low coolant
warning light. If this light
comes on, your system is
low on coolant and the
engine may overheat.
The warning light should come on briefly, as a check,
when you turn on the ignition.
When it comes on, you will also hear a warning tone at
several beats per second for 10 seconds. SeeEngine
Coolant (Gas and DURAMAX™ engines) on page 5-32
orEngine Coolant (Caterpillar
®Diesel Engines) on
page 5-35and have your vehicle serviced as soon as
you can.
This light may also come on if your vehicle is equipped
with the automatic engine shutdown system and
engine shutdown has begun. SeeEngine Alarm and
Automatic ShutdownunderStarting Your Diesel Engine
on page 2-14.
Wait to Start Indicator
If your vehicle has the DURAMAX™ 6600, you will have
glow plugs. If your vehicle has the DURAMAX™ 7800,
you will have glow plugs and an inlet heater. If your
vehicle has a Caterpillar
®engine, you will have an inlet
heater.
The light in the center of
the instrument panel will
come on when the
inlet heater is on and the
ignition key is in RUN.
Wait until the indicator light turns off before turning the
ignition key to START.
3-36

•Put on extra clothing or wrap a blanket around you.
If you have no blankets or extra clothing, make
body insulators from newspapers, burlap bags, rags,
floor mats — anything you can wrap around
yourself or tuck under your clothing to keep warm.
You can run the engine to keep warm, but be careful.
{CAUTION:
Snow can trap exhaust gases under your
vehicle. This can cause deadly CO (carbon
monoxide) gas to get inside. CO could
overcome you and kill you. You can not see it
or smell it, so you might not know it is in your
vehicle. Clear away snow from around the
base of your vehicle if any is blocking your
exhaust pipe. And check around again from
time to time to be sure snow does not
collect there.
Open a window just a little on the side of the
vehicle that is away from the wind. This will
help keep CO out.
Run your engine only as long as you must. This saves
fuel. When you run the engine, make it go a little
faster than just idle. That is, push the accelerator
slightly. This uses less fuel for the heat that you get and
it keeps the battery (or batteries) charged. You will
need a well-charged battery (or batteries) to restart the
vehicle, and possibly for signaling later on with your
headlamps. Let the heater run for a while.
4-28

Service............................................................5-3
Doing Your Own Service Work.........................5-4
Two Safety Cautions about Engine Fan
Breakage...................................................5-5
Fuel................................................................5-6
Gasoline Octane............................................5-6
Gasoline Specifications....................................5-6
Additives.......................................................5-7
Diesel Engine Fuel.........................................5-8
What Fuel to Use...........................................5-8
Very Cold Weather Operation.........................5-10
Water in Fuel...............................................5-10
Running Out of Fuel.....................................5-15
Fuel Filter Replacement.................................5-15
Fuels in Foreign Countries.............................5-16
Filling Your Tank..........................................5-17
Filling a Portable Fuel Container.....................5-18
Checking Things Under the Hood....................5-18
Hood Latches...............................................5-19
Engine Oil (Caterpillar
®Diesel Engine).............5-20
Engine Oil (Gasoline Engine)..........................5-20
Engine Oil (DURAMAX™ Diesel).....................5-25
Engine Air Cleaner/Filter................................5-30
Automatic Transmission Fluid.........................5-31
Manual Transmission Fluid.............................5-32Engine Coolant (Gas and
DURAMAX™ engines)................................5-32
Engine Coolant (Caterpillar
®Diesel Engines).....5-35
Coolant Surge Tank Pressure Cap..................5-35
Engine Overheating.......................................5-36
Cooling System............................................5-38
Engine Fan Noise.........................................5-43
Power Steering Fluid.....................................5-43
Windshield Washer Fluid................................5-44
Brakes........................................................5-46
Battery........................................................5-55
Jump Starting...............................................5-56
Rear Axle.......................................................5-61
Rear Axle Shift Motor....................................5-61
Noise Control System.....................................5-62
Tampering with Noise Control System
Prohibited.................................................5-62
Bulb Replacement..........................................5-63
Replacement Bulbs.......................................5-63
Windshield Wiper Blade Replacement..............5-63
Other Service Items........................................5-64
Fuel Filter....................................................5-64
Primary Fuel Filter and Water Separator..........5-65
Secondary Fuel Filter and Water
Separator/Heater.......................................5-66
Section 5 Service and Appearance Care
5-1

The following explains your cooling system and how to
add coolant when it is low. If you have a problem
with engine overheating, seeEngine Overheating on
page 5-36.
A 50/50 mixture of clean, drinkable water and
DEX-COOL
®coolant will:
•Give freezing protection down to−34°F (−37°C).
•Give boiling protection up to 252°F (122°C).
•Protect against rust and corrosion.
•Help keep the proper engine temperature.
•Let the warning lights and gages work as they
should.
Notice:Using coolant other than DEX-COOL
®may
cause premature engine, heater core or radiator
corrosion. In addition, the engine coolant may
require changing sooner, at 30,000 miles (50 000 km)
or 24 months, whichever occurs rst. Any repairs
would not be covered by your warranty. Always use
DEX-COOL
®(silicate-free) coolant in your vehicle.
What to Use
Use a mixture of one-halfclean, drinkable waterand
one-half DEX-COOL®coolant which won’t damage
aluminum parts. If you use this coolant mixture,
you don’t need to add anything else.
{CAUTION:
Adding only plain water to your cooling
system can be dangerous. Plain water, or
some other liquid such as alcohol, can boil
before the proper coolant mixture will. Your
vehicle’s coolant warning system is set for the
proper coolant mixture. With plain water or the
wrong mixture, your engine could get too hot
but you would not get the overheat warning.
Your engine could catch re and you or others
could be burned. Use a 50/50 mixture of clean,
drinkable water and DEX-COOL
®coolant.
Notice:If you use an improper coolant mixture,
your engine could overheat and be badly damaged.
The repair cost would not be covered by your
warranty. Too much water in the mixture can freeze
and crack the engine, radiator, heater core and
other parts.
If you have to add coolant more than four times a year,
have your dealer check your cooling system.
Notice:If you use the proper coolant, you do not
have to add extra inhibitors or additives which claim
to improve the system. These can be harmful.
5-33

If No Steam Is Coming From Your
Engine
An overheat warning, along with a low coolant light, can
indicate a serious problem. SeeLow Coolant Warning
Light on page 3-36for more information.
If you get an engine overheat warning with no low
coolant light, but see or hear no steam, the problem may
not be too serious. Sometimes the engine can get a
little too hot when you:
•Climb a long hill on a hot day.
•Stop after high-speed driving.
•Idle for long periods in traffic.
If you get the overheat warning with no sign of steam,
try this for a minute or so:
1. In heavy traffic, let the engine idle in neutral while
stopped. If it is safe to do so, pull off the road, shift
to park or neutral and let the engine idle.2. Turn on your heater to full hot at the highest fan
speed and open the window as necessary.
3. If climbing a hill, downshift to raise engine and fan
speeds.
If you no longer have the overheat warning, you can
drive. Just to be safe, drive slower for about 10 minutes.
If the warning doesn’t come back on, you can drive
normally.
If the warning continues and you have not stopped, pull
over, stop, and park your vehicle right away.
If there’s still no sign of steam, you can push down the
accelerator until the engine speed is about twice as
fast as normal idle speed for at least three minutes while
you’re parked. If you still have the warning,turn off
the engine and get everyone out of the vehicleuntil it
cools down.
You may decide not to lift the hood but to get service
help right away.
5-37

Cooling System
When you decide it’s safe to lift the hood, here’s what
you’ll see:
A. Engine Fan
B. Coolant Surge Tank
If your vehicle has a Caterpillar
®diesel engine, see the
Caterpillar®Diesel Engine Operation and Maintenance
Manual provided with your vehicle.
If the coolant inside the coolant surge tank is boiling,
don’t do anything else until it cools down. The vehicle
should be parked on a level surface.The coolant level should
be at COLD FILL or
higher. If it isn’t, you may
have a leak at the
pressure cap or in the
radiator hoses, heater
hoses, radiator, water
pump or somewhere else
in the cooling system.
{CAUTION:
Heater and radiator hoses, and other engine
parts, can be very hot. Do not touch them. If
you do, you can be burned.
Do not run the engine if there is a leak. If you
run the engine, it could lose all coolant. That
could cause an engine re, and you could be
burned. Get any leak xed before you drive the
vehicle.
5-38

If there seems to be no leak, start the engine again.
The engine cooling fan speed should increase when idle
speed is doubled by pushing the accelerator pedal
down. If it doesn’t, your vehicle needs service. Turn off
the engine.
Notice:Engine damage from running your engine
without coolant is not covered by your warranty.
Notice:Using coolant other than DEX-COOL
®may
cause premature engine, heater core or radiator
corrosion. In addition, the engine coolant may
require changing sooner, at 30,000 miles (50 000 km)
or 24 months, whichever occurs rst. Any repairs
would not be covered by your warranty. Always use
DEX-COOL
®(silicate-free) coolant in your vehicle.
How to Add Coolant to the Coolant
Surge Tank
If you haven’t found a problem yet, check to see if
coolant is visible in the surge tank. If coolant is visible
but the coolant level isn’t at COLD FILL or higher, add a
50/50 mixture ofclean, drinkable waterand DEX-COOL
®
coolant at the coolant surge tank, but be sure the
cooling system, including the coolant surge tank
pressure cap, is cool before you do it. SeeEngine
Coolant (Gas and DURAMAX™ engines) on page 5-32
orEngine Coolant (Caterpillar
®Diesel Engines) on
page 5-35for more information.
5-39