2001 CHEVROLET C3500 HD service

4-22
Highway Hypnosis
Is there actually such a condition as ªhighway hypnosisº?
Or is it just plain falling asleep at the wheel? Call it
highway hypnosis, lack of awareness, or whatever.
There is something about an easy stretch of road with
the same scenery, along with the hum of the tires on the
road, the drone of the engine, and the rush of the wind
against the vehicle that can make you sleepy. Don't let
it happen to you! If it does, your vehicle can leave the
road in less than a second, and you could crash and
be injured.
What can you do about highway hypnosis? First, be
aware that it can happen.
Then here are some tips:

Make sure your vehicle is well ventilated, with a
comfortably cool interior.

Keep your eyes moving. Scan the road ahead
and to the sides. Check your mirrors and your
instruments frequently.

If you get sleepy, pull off the road into a rest, service
or parking area and take a nap, get some exercise, or
both. For safety, treat drowsiness on the highway as
an emergency.
Hill and Mountain Roads
Driving on steep hills or mountains is different from
driving in flat or rolling terrain.

4-28
Recreational Vehicle Towing
There may be times when you want to tow your vehicle
behind another vehicle for use at your destination.
Be sure to use the proper towing equipment designed
for recreational vehicle towing. Follow the instructions
for the towing equipment.
Your vehicle should not be towed with all four wheels
on the ground. The transmission has no provisions for
internal lubrication while being towed. To properly tow
the vehicle, it should be placed on a platform trailer with
all four wheels off the ground.
In rare cases when it's unavoidable that the vehicle is
to be towed with all four wheels on the ground, the
propeller shaft to axle yoke orientation should be marked
and the propeller shaft removed following the applicable
service manual removal/installation procedure.
Dust or dirt can enter the back of the transmission
through the opening created by removing the propeller
shaft if proper protection is not provided. Also, check
the transmission fluid level before driving the truck.

4-31
Towing a Trailer
CAUTION:
If you don't use the correct equipment and drive
properly, you can lose control when you pull a
trailer. For example, if the trailer is too heavy,
the brakes may not work well
-- or even at all.
You and your passengers could be seriously
injured. Pull a trailer only if you have followed
all the steps in this section. Ask your dealer for
advice and information about towing a trailer
with your vehicle.
NOTICE:
Pulling a trailer improperly can damage your
vehicle and result in costly repairs not covered by
your warranty. To pull a trailer correctly, follow
the advice in this part, and see your dealer for
important information about towing a trailer with
your vehicle. Additional rear axle maintenance is
required for a vehicle used to tow a trailer. See
ªScheduled Maintenance Servicesº in the Index.
To identify what the vehicle trailering capacity is for
your vehicle, you should read the information in
ªWeight of the Trailerº that appears later in this section.
If yours was built with trailering options, as many are,
it's ready for heavier trailers. But trailering is different
than just driving your vehicle by itself. Trailering means
changes in handling, durability and fuel economy.
Successful, safe trailering takes correct equipment,
and it has to be used properly.
That's the reason for this part. In it are many time
-tested,
important trailering tips and safety rules. Many of these
are important for your safety and that of your passengers.
So please read this section carefully before you pull
a trailer.

4-38 When You Are Ready to Leave After
Parking on a Hill
1. Apply your regular brakes and hold the pedal down
while you:

Start your engine;

Shift into a gear; and

Release the parking brake.
2. Let up on the brake pedal.
3. Drive slowly until the trailer is clear of the chocks.
4. Stop and have someone pick up and store the chocks.
Maintenance When Trailer Towing
Your vehicle will need service more often when you're
pulling a trailer. See the Maintenance Schedule for
more on this. Things that are especially important
in trailer operation are automatic transmission fluid
(don't overfill), engine oil, axle lubricant, belts, cooling
system and brake system. Each of these is covered inthis manual, and the Index will help you find them
quickly. If you're trailering, it's a good idea to review
these sections before you start your trip.
Check periodically to see that all hitch nuts and bolts
are tight.
Power Winches
If you wish to use a power winch on your vehicle, only
use it when your vehicle is stationary or anchored.
NOTICE:
Using a power winch with the transmission
in gear may damage the transmission. When
operating a power winch, always leave the
transmission in NEUTRAL (N).
Use the regular brakes, set the parking brake, or block
the wheels to keep your vehicle from rolling.

5-7
Attach the cable at least 18 inches (45 cm) away
from the dead battery, but not near engine parts that
move. The electrical connection is just as good
there, but the chance of sparks getting back to the
battery is much less.
10. Now start the vehicle with the good battery and run
the engine for awhile.
11. Try to start the vehicle with the dead battery.
If it won't start after a few tries, it probably
needs service.Jumper Cable Removal
A. Heavy, Unpainted Metal Engine Part
B. Good Battery
C. Dead Battery

5-8
To disconnect the jumper cables from both vehicles,
do the following:
1. Disconnect the black negative (
-) cable from the
heavy, unpainted metal engine part on the vehicle
that had the dead battery.
2. Disconnect the black negative (
-) cable from
the negative (
-) terminal on the vehicle with the
good battery.
3. Disconnect the red positive (+) cable from the
vehicle with the good battery.
4. Disconnect the red positive (+) cable from the
other vehicle.
Towing Your Vehicle
Consult your dealer or a professional towing service if
you need to have your vehicle towed. See ªRoadside
Assistanceº and ªRecreational Vehicle Towingº in
the Index.
Engine Overheating (Gasoline Engine)
You will find a coolant temperature gage on your
vehicle's instrument panel. See ªEngine Coolant
Temperature Gageº in the Index.If your vehicle has a diesel engine, see ªEngine
Overheatingº in the Diesel Engine Supplement.
Overheated Engine Protection
Operating Mode
Should an overheated engine condition exist and the
REDUCED ENGINE POWER light is displayed, an
overheat protection mode which alternates firing groups
of cylinders helps prevent engine damage. In this mode,
you will notice a loss in power and engine performance.
This operating mode allows your vehicle to be driven to
a safe place in an emergency. Towing a trailer in the
overheat protection mode should be avoided.
NOTICE:
After driving in the overheated engine protection
operating mode, to avoid engine damage, allow
the engine to cool before attempting any repair.
The engine oil will be severely degraded. Repair
the cause of coolant loss and change the oil. See
ªEngine Oilº in the Index.

5-10 If No Steam Is Coming From Your Engine
If you get an engine overheat warning 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.

Tow a trailer. See ªDriving on Gradesº in the Index.
If you get the overheat warning with no sign of steam,
try this for a minute or so:
1. If you have an air conditioner and it's on, turn it off.
2. Turn on your heater to full hot at the highest fan
speed and open the window as necessary.
3. If you're in a traffic jam, shift to NEUTRAL (N);
otherwise, shift to the highest gear while
driving
-- AUTOMATIC OVERDRIVE (
) for
automatic transmissions, FIFTH (5) gear for
manual transmissions.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, pull over, stop, and park your
vehicle right away.
If there's still no sign of steam, 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 vehicle until it cools
down. Also, see ªOverheated Engine Protection
Operating Modeº listed previously in this section.
You may decide not to lift the hood but to get service
help right away.

5-13
NOTICE:
When adding coolant, it is important that you use
only DEX
-COOL
(silicate-free) coolant.
If coolant other than DEX-COOL is added to the
system, premature engine, heater core or
radiator corrosion may result. In addition, the
engine coolant will require change sooner
-- at
30,000 miles (50 000 km) or 24 months,
whichever occurs first. Damage caused by the use
of coolant other than DEX
-COOL
is not
covered by your new vehicle warranty.
If there seems to be no leak, start the engine again.
See if the engine cooling fan speed increases when idle
speed is doubled by pushing the accelerator pedal
down. If it doesn't, your vehicle needs service. Turn off
the engine.
How to Add Coolant to the Coolant
Recovery Tank (Gasoline Engines)
If you haven't found a problem yet, but the coolant level
isn't at or above the COLD mark, add a 50/50 mixture
of clean, drinkable water and DEX
-COOL
engine
coolant at the coolant recovery tank. See ªEngine
Coolantº in the Index for more information.
CAUTION:
Adding only plain water to your cooling system
can be dangerous. Plain water, or some other
liquid like 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 wouldn't
get the overheat warning. Your engine could
catch fire and you or others could be burned.
Use a 50/50 mixture of clean, drinkable water
and DEX
-COOL
coolant.