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Towing
Towing Your Vehicle
Consult your dealer or a professional towing service
if you need to have your disabled vehicle towed.
SeeRoadside Assistance Program on page 408.
Releasing Air-Operated Parking Brakes
If your vehicle has air brakes, you could have a
special towing problem. If your vehicle has to
be towed because of a complete loss of air
pressure from both systems, the parking brakes
will have automatically engaged. The tow operator
can release the brakes manually by using the
following steps. Then your vehicle can be towed
with all wheels or only the rear wheels on
the ground.
1. Block the wheels of the vehicle.2. Remove the release stud and nut from the
side of the brake chamber. Some chambers
have studs which are visible at all times.
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3. Remove the rubber
cap from the rear
of the chamber.
4. Put the release stud, nut and flat washer into
the chamber.
5. Turn the stud clockwise a quarter of a turn.6. Turn the stud nut
clockwise several
turns to release
the brakes.
Follow the same
procedure to
release the other
brake or brakes.
7. At the repair facility, apply air pressure of at
least 70 psi (480 kPa) to the brake chambers,
either from an external air supply or the
vehicle’s air system.
8. Turn the stud nut counterclockwise several
turns. Remove the stud from the chamber.
9. Replace the stud and washer and tighten the
nut into the side of the chamber.
10. Replace the rubber cap.
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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
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Power Steering Fluid
SeeScheduled Maintenance on page 363to
determine when to check your power steering fluid.
How To Check Power Steering Fluid
Check your power steering fluid only when the
engine is warm. If the engine is not warm, you
probably will not get an accurate reading.
If the fluid level is between the MIN (Minimum) and
MAX (Maximum) marks, you have enough. If you
need fluid, add only enough of the proper fluid to
bring it in between the MIN and MAX marks.
If your power steering fluid level is low, this can
cause the brake or service brakes soon warning
lights to come on. In addition, the steering
effort and emergency brake distance could
increase.If either light remains on after you have added
power steering fluid to the proper level, then shut
off the engine for 10 seconds. This should
reset the brake warning lights. If one or both lights
stay on, see “Hydraulic Brake System Warning
Lights” underBrake System Warning Light
on page 169for more information.
What to Use
To determine what kind of fluid to use, see
Part C: Recommended Fluids and Lubricants on
page 397.
Notice:When adding power steering uid or
making a complete uid change, always
use the proper uid. Failure to use the proper
uid can cause leaks and damage hoses
and seals.
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Brakes
Brake Fluid
If your vehicle has
hydraulic brakes, there
is a brake master
cylinder in the engine
compartment on the
driver side of the vehicle.
Refer to the
Maintenance Schedule
to determine when to
check the brake fluid.
{CAUTION:
Do not add brake uid before you check
the level. If you do, you could get too
much brake uid. Brake uid could spill
on the hot engine and it can catch re.
You could be burned and your vehicle
could be damaged. See “Checking Brake
Fluid” in this section.
Checking Brake Fluid
Apply the brake pedal several times with the
ignition off. The brake fluid reservoir is in
the engine compartment on the driver side of the
vehicle. Clean one of the reservoir caps and
the area around the cap, and remove it.
The fluid level should be
even with the bottom
ring of the filler opening.
If it is low, add enough
fluid to fill the reservoir to
the proper level.
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What to Add
Use the proper fluid listed in the Maintenance
Schedule. Use new brake fluid from a sealed
container only.
Always clean the brake fluid reservoir cap/cover
and the area around the cap/cover before
removing it. This will help keep dirt from entering
the reservoir.
{CAUTION:
With the wrong kind of uid in the brake
system, the brakes may not work well, or
they may not even work at all. This could
cause a crash. Always use the proper
brake uid.Notice:
Using the wrong uid can badly damage
brake system parts. For example, just a few
drops of mineral-based oil, such as engine
oil, in the brake system can damage brake
system parts so badly that they will have to
be replaced. Do not let someone put in the
wrong kind of uid, and do not use DOT-5
silicone brake uid.
If you spill brake uid on your vehicle’s
painted surfaces, the paint nish can be
damaged. Be careful not to spill brake uid
on your vehicle. If you do, wash it off
immediately. SeeWashing Your Vehicle on
page 335.
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Four-Wheel Disc Brakes
(Hydraulic Only)
Your vehicle has four-wheel disc brakes.
Some driving conditions or climates may cause a
brake squeal when the brakes are first applied
or lightly applied. This does not mean something
is wrong with the brakes.
Brake linings should always be replaced as
complete axle sets.
Four-Wheel and Six-Wheel Drum
Brakes (Air Only)
The brake drums should be removed and
inspected each time the tires are removed for
rotation or changing. When you have the
front brakes replaced, have the rear brakes
inspected, too.
Brake linings should always be replaced as
complete axle sets.
Brake Pedal Travel
See your dealer if the brake pedal does not return
to normal height, or if there is a rapid increase in
pedal travel. This could be a sign that brake service
is needed.
Brake Adjustment
Every time you make a brake stop, the brakes
adjust for wear.
Brake Adjustment on Air Braked
Vehicles
Your vehicle has automatic slack adjusters.
Every time you make a brake stop, the brakes
automatically adjust for wear. Slack adjusters
should never be manually adjusted to correct
excessive brake chamber pushrod stroke.
Excessive brake chamber pushrod stroke means
that the brake system needs to be serviced by
a qualified service technician.
Notice:Do not manually adjust automatic slack
adjusters. Manual adjustment of the automatic
slack adjusters can result in a degradation of
the slack adjuster performance over time.
If the brake chamber pushrod stroke is out of
adjustment, the brake system needs to be
serviced by a quali ed service technician.
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Replacing Brake System Parts
The braking system on a vehicle is complex.
Its many parts have to be of top quality and work
well together if the vehicle is to have really
good braking. Your vehicle was designed and
tested with top-quality GM brake parts. When
you replace parts of the braking system — for
example, when the brake linings wear down and
you need new ones put in — be sure you get
new approved GM replacement parts. If you do
not, the brakes may no longer work properly.
For example, if someone puts in brake linings that
are wrong for your vehicle, the balance between
the front and rear brakes can change — for
the worse. The braking performance you have
come to expect can change in many other ways
if someone puts in the wrong replacement
brake parts.
Air Brake Systems
If your vehicle has air brakes, it is important to
get rid of moisture in the system. Moisture will
damage the system if it is not removed daily.There are two ways to do this. One is automatic
through the air brake vehicle’s air dryer with integral
automatic moisture ejector that purges air from the
system through a self-contained reservoir. The
other way to drain moisture from the air brake
system is to manually activate drain valves at each
reservoir. Drain the air reservoirs occasionally to be
sure the air dryer is working properly.
Drain the air brakes at full system pressure. To be
sure you are at full pressure, check the air pressure
gage. It should read at least 100 psi (692 kPa).
Air Dryer
If your vehicle has air brakes, it has an air dryer
mounted on the passenger side frame rail. This
collects and removes dirt, moisture, or other foreign
matter from the air prior to entering the brake
system. The dryer also acts as a moisture ejector.
It automatically ejects the moisture when the
compressor cycles. The purge tank has a manual
drain valve that must be drained every day. See
“Air Brake Systems” for the manual drain procedure.
The dryer has a filter that you need to change at
intervals. SeeScheduled Maintenance on page 363
for more about servicing this filter.
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