
Engine Overheating................................... 288
Cooling System (Gas and
DURAMAX
®/Isuzu Engines).................... 290
Engine Fan Noise..................................... 294
Power Steering Fluid................................. 295
Windshield Washer Fluid........................... 296
Brakes...................................................... 297
Battery...................................................... 304
Jump Starting............................................ 305
Rear Axle.................................................... 311
Rear Axle Shift Motor................................ 312
Four-Wheel Drive........................................ 312
Front Axle................................................... 313
Noise Control System................................. 314
Tampering with Noise Control System
Prohibited.............................................. 314
Bulb Replacement....................................... 315
Windshield Wiper Blade Replacement....... 316Other Service Items.................................... 317
Fuel Filter.................................................. 317
Primary Fuel Filter and Water Separator...... 317
Secondary Fuel Filter and Water
Separator/Heater (Caterpillar
®Diesel)...... 318
Automatic Ether Injection System
(Caterpillar
®Diesel)................................ 318
Front Wheel Bearings with
Oil-Filled Hubs....................................... 319
Air Conditioning System............................ 320
Tires............................................................ 321
Inflation - Tire Pressure............................. 322
Wheel Loading.......................................... 323
Dual Tire Operation................................... 323
When It Is Time for New Tires.................. 324
Wheel Alignment and Tire Balance............ 324
Tightening the Wheel Nuts........................ 325
Wheel Replacement.................................. 328
If a Tire Goes Flat.................................... 330
Section 5 Service and Appearance Care
246

Engine Coolant (Gas and
DURAMAX
®/Isuzu Engines)
The cooling system in your vehicle is filled with
DEX-COOL®engine coolant. This coolant is
designed to remain in your vehicle for five years or
150,000 miles (240 000 km), whichever occurs
first, if you add only DEX-COOL
®extended
life coolant.
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 288.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 265°F (129°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.
284

What to Use
Use a mixture of one-half clean, drinkable water
and one-half DEX-COOL®coolant which will
not damage aluminum parts. If you use this coolant
mixture, you do not 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 extra inhibitors and/or
additives in your vehicle’s cooling system, you
could damage your vehicle. Use only the
proper mixture of the engine coolant listed in
this manual for the cooling system. See
Part C: Recommended Fluids and Lubricants
on page 397for more information.
285

Coolant Surge Tank Pressure Cap
The coolant surge tank pressure cap is located in
the engine compartment, on the driver’s side of
the vehicle.
Notice:Your vehicle’s surge tank pressure cap
is designed for use with medium-duty cooling
systems only. If the surge tank pressure cap is
not tightly installed, coolant loss and possible
engine damage may occur. Be sure the cap is
properly and tightly secured.
Engine Overheating
You will find an engine coolant temperature gage,
as well as a low coolant warning light, on your
vehicle’s instrument panel. SeeEngine Coolant
Temperature Gage on page 173andLow Coolant
Warning Light on page 173for more information.
Your vehicle also has a check gages warning light
on the instrument panel. SeeCheck Gages
Warning Light on page 180for more information.
If Steam Is Coming From Your Engine
{CAUTION:
Steam from an overheated engine can
burn you badly, even if you just open the
hood. Stay away from the engine if you
see or hear steam coming from it. Just
turn it off and get everyone away from the
vehicle until it cools down. Wait until
there is no sign of steam or coolant
before you open the hood.
If you keep driving when your engine is
overheated, the liquids in it can catch re.
You or others could be badly burned.
Stop your engine if it overheats, and get
out of the vehicle until the engine is cool.
Notice:If your engine catches re because
you keep driving with no coolant, your vehicle
can be badly damaged. The costly repairs
would not be covered by your warranty.
288

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 173for 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 (P) or
NEUTRAL and let the engine idle.
2. Turn on your heater to full hot at the highest
fan speed and open the windows 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 does not 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 is 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 are parked. If you still have
the warning, turn off the engine and get everyone
out of the vehicle until it cools down.
You may decide not to lift the hood but to get
service help right away.
289

If no coolant is visible in the surge tank, add
coolant as follows:
{CAUTION:
Steam and scalding liquids from a hot
cooling system can blow out and burn
you badly. They are under pressure, and if
you turn the coolant surge tank pressure
cap — even a little — they can come out at
high speed. Never turn the cap when the
cooling system, including the coolant
surge tank pressure cap, is hot. Wait for
the cooling system and coolant surge
tank pressure cap to cool if you ever have
to turn the pressure cap.
{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:In cold weather, water can freeze and
crack the engine, radiator, heater core and
other parts. Use the recommended coolant and
the proper coolant mixture.
292

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.
341

E
Electrical System
Add-On Equipment................................... 340
Fuses and Circuit Breakers...................... 341
Fusible Links............................................ 341
Headlamp Wiring..................................... 341
Instrument Panel Fuse Block................... 342
Power Windows and Other Power
Options................................................. 341
Underhood Fuse Block............................. 344
Windshield Wiper Fuses........................... 341
Engine
Air Cleaner/Filter...................................... 280
Alarm and Automatic Shutdown................ 104
Battery..................................................... 304
Change Engine Oil Light.......................... 176
Check and Service Engine Soon Light..... 174
Checks Before Operating......................... 109
Coolant...........................................284, 287
Coolant Heater......................................... 111
Coolant Temperature Gage...................... 173
Diesel Engine Exhaust Brake................... 112
Drive Belt Routing.................................... 355
Exhaust................................................... 131
Exhaust Restrictor.................................... 108
Fan Breakage.......................................... 250Engine (cont.)
Fan Noise................................................ 294
High Idle System..................................... 106
Oil ...................................................268, 272
Oil Life System.......................276, 278, 279
Overheating............................................. 288
Overspeed Warning Light......................... 177
Reduced Power Light............................... 179
Shutdown Warning Light.......................... 177
Speed Limiter.......................................... 164
Starter Over-Crank Protection.................... 97
Starting Your Diesel................................. 100
Starting Your Gasoline............................... 97
Entry Lighting.............................................. 154
Event Data Recorders (EDR)...................... 409
Exhaust Brake Indicator Light...................... 178
Exhaust Restrictor....................................... 108
Extender, Safety Belt..................................... 41
Exterior Lamps............................................ 150
F
Filter
Engine Air Cleaner................................... 280
Filter Minder Gage...................................... 182
Finish Damage............................................ 338
Fixed Mast Antenna.................................... 204
421