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{CAUTION:
If you get fuel on yourself and then something
ignites it, you could be badly burned. Fuel can
spray out on you if you open the fuel cap too
quickly. This spray can happen if the tank is nearly
full, and is more likely in hot weather. Open the
fuel cap slowly and wait for any “hiss” noise to
stop. Then unscrew the cap all the way.
When reinstalling the cap, turn it clockwise until it is
tight.
Notice:If you need a new fuel cap, be sure to get
the right type. Your dealer/retailer can get one
for you. If you get the wrong type, it may not fit
properly. This may cause the malfunction indicator
lamp to light and may damage the fuel tank and
emissions system. SeeMalfunction Indicator Lamp
on page 3-36.If the vehicle has dual tanks, fill the driver side tank,
or forward tank, first. The fuel gage will give better
readings this way. The gage will show the total fuel left
in both tanks.
If the vehicle is a C4/C5 model and has dual tanks, the
engine must be off when refueling or the fuel transfer
system may become inoperable.
If the vehicle has a single tank with dual fillers, where
there is a filler on each side of the vehicle, do not
attempt to fill the tank through both fillers at the same
time. Do not fill the tank with both caps removed or
over-filling the tank and fuel spillage can result.
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Page 242 of 376

How to Inspect the Engine Air Cleaner/
Filters (Gas V8 8.1L, Caterpillar 7.2L and
Isuzu 7.8L Diesel Engines)
{CAUTION:
Operating the engine with the air cleaner/filter off
can cause you or others to be burned. The air
cleaner not only cleans the air; it helps to stop
flames if the engine backfires. If it is not there and
the engine backfires, you could be burned. Do not
drive with it off, and be careful working on the
engine with the air cleaner/filter off.
Notice:If the air cleaner/filter is off, a backfire can
cause a damaging engine fire. And, dirt can easily get
into the engine, which will damage it. Always have
the air cleaner/filter in place when you are driving.
The engine air cleaner/filter is located in the center of
the engine compartment.To inspect the engine air cleaner/filter:
1. Disconnect the air
compressor hose by
pinching the connector
ring to release the
connector lock.
2. Unclip the four clips that hold the upper housing to
the lower housing and remove the upper housing.
3. Remove the filter from the vehicle and lightly shake
the filter to release loose dust and dirt. If the filter
remains caked with dirt, a new filter is required.
4. Reinstall the upper housing and make sure that the
air compressor hose is reconnected by pushing the
connector back onto the port. Listen for the
connector to click to be sure that the air compressor
hose is securely locked and connected. Isuzu 7.8L Diesel Only
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Hood Inlet Seal
If the vehicle is being used in heavy snow conditions or
for snow plowing, there is a possibility of snow and
ice build up in the inlet to the air cleaner, which
can block airflow to the engine and affect impacting
engine performance.
To prevent this from happening, remove the hood
inlet seal:
1. Loosen the clamp that holds the seal to the air
cleaner.
2. Slide the seal off.3. Store the seal in the inlet, located on the underside
of the hood.
4. Store the air cleaner clamp on the coolant surge
tank. Pull the overflow tube out of the white plastic
retainer, slip the clamp over and reinstall the hose.
Replace the air cleaner seal during non-snow or non-icy
conditions.
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Page 248 of 376
{CAUTION:
You can be burned if you spill coolant on hot
engine parts. Coolant contains ethylene glycol and
it will burn if the engine parts are hot enough. Do
not spill coolant on a hot engine.
1. You can remove the
coolant surge tank
pressure cap when
the cooling system,
including the coolant
surge tank pressure
cap and upper radiator
hose, is no longer hot.
Turn the pressure cap slowly counterclockwise
about one full turn. If you hear a hiss, wait for that to
stop. A hiss means there is still some pressure left.
2. Then keep turning the pressure cap slowly, and
remove it.3. Fill the coolant surge tank with the proper mixture,
to the FULL COLD mark.
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Page 270 of 376

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.
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Page 283 of 376
First, use these pictures to decide what kind of wheels
you have.
Then, refer to the following steps for the wheels
you have.Hub-Piloted Wheels, 8-Hole or 10-Hole
The studs and nuts used with these wheels have
right-hand threads.
1. With intermittent pilot pads, position a pad at
12 o’clock to center the wheel and reduce run-out.
2. Put the tire and rim assembly on the axle hub.
Install the outer rear tire and rim assembly so
that its valve stem is exactly opposite the valve stem
on the inner tire and rim assembly.
3. Put on the wheel nuts.
4. Finger-tighten the nuts.
5. Oil the surfaces (B)
between the nuts (C)
and washers (A). Do
not oil the studs or the
threads of the nut. Hub-Piloted Type,
8-Hole
Hub-Piloted Type,
10-Hole
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Page 297 of 376

Electrical System
Add-On Electrical Equipment
Notice:Do not add anything electrical to the
vehicle unless you check with your dealer/retailer
first. Some electrical equipment can damage
the vehicle and the damage would not be covered
by the vehicle’s warranty. Some add-on electrical
equipment can keep other components from
working as they should.
Add-on equipment can drain the vehicle battery, even if
the vehicle is not operating.
The vehicle has an airbag system. Before attempting to
add anything electrical to the vehicle, seeServicing
Your Airbag-Equipped Vehicle on page 1-58.
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.
The starter and other circuits have fusible links. The size
is printed on the insulation. If the insulation is burned
beyond recognition, consult your dealer/retailer for the
proper size. Replace a fusible link 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.
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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 the 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.
Instrument Panel Fuse Block
There are two instrument panel fuse blocks located
behind the instrument panel on the passenger side of
the vehicle.
Be sure to replace fuses with fuses of the same rating.
Do not use fuses of higher amperage than those
indicated on the fuse block.
5-96