2003 CHEVROLET ASTRO engine

Tow/Haul Mode
The tow/haul mode is a feature that assists when pulling
a heavy trailer. The purpose of the tow/haul mode is:
e to reduce the frequency of shifts when pulling a
heavy trailer.
to provide the same shift feel when pulling a heavy
trailer as when the vehicle is unloaded.
to reduce the need to change throttle position when
pulling a heavy trailer.
This feature is turned on or off by pressing a button on
the column shift lever. When the feature
is on, a
light on the instrument panel will illuminate to indicate
that the tow/haul mode has been selected.
See
Tow/Haul Mode Light on page 3-36. The tow/haul
mode is automatically turned
off each time the vehicle
is started.
The tow/haul mode is most effective when the vehicle
and trailer combined weight is at least
75% of the Gross
Vehicle Weight Rating (GVWR) and the maximum
trailer weight rating for the vehicle. The tow/haul
mode for hauling a heavy trailer is most
useful under the following conditions:
When driving through hilly terrain at speeds below
55 mph
(88 km/h).
When driving in low speed or stop and go traffic
below
55 mph (88 km/h).
When driving in parking lots.
Operating in the tow/haul mode when not pulling a
heavy trailer will not cause damage to the vehicle,
but you may experience reduced fuel economy
and undesirable petformance from the engine and
transmission. The tow/haul mode should be used only
when pulling a heavy trailer.
Weight of the Trailer
How heavy can a trailer safely be?
It depends on how you plan to use your rig. For example,
speed, altitude, road grades, outside temperature and
how much your vehicle is used to pull a trailer are all
important. And, it can also depend on any special
equipment that you have on your vehicle.
4-33

Driving with a Trailer
If you ~ ve a rear-most window open and
you pull a trailer with your vehicle, carbon monoxide (CO) could come into your vehicle.
You can’t see or smell
CO. It can cause
unconsciousness or death. See “Engine
Exhaust” in the Index.
To maximize your safety
when towing a trailer:
Have your exhaust system inspected for
leaks, and make necessary repairs before
starting on your trip.
Keep the rear-most windows closed.
If exhaust does come into your vehicle
through a window
in the rear or another
opening, drive with your front, main
heating or cooling system on and with the
fan on any speed. This will bring fresh,
outside air into your vehicle.
Do not use
the climate control setting for maximum air because
it only recirculates the air inside
your vehicle. See “Climate Controls” in
the Index. Towing
a trailer requires a certain amount of experience.
Before setting out for the open road, you’ll want to get
to know your rig. Acquaint yourself with the feel of
handling and braking with the added weight of the trailer.
And always keep in mind that the vehicle you are
driving is now a good deal longer and not nearly as
responsive as your vehicle is by itself.
Before you start, check the trailer hitch and platform
(and attachments), safety chains, electrical connector,
lamps, tires and mirror adjustment. If the trailer has
electric brakes, start your vehicle and trailer moving and
then apply the trailer brake controller by hand to be
sure the brakes are working. This lets you check your
electrical connection at the same time.
During your trip, check occasionally
to be sure that
the load
is secure, and that the lamps and any trailer
brakes are still working.
4-37

Driving On Grades Parking on Hills
Reduce speed and shift to a lower gear before you start
down a long or steep downgrade.
If you don’t shift
down, you might have to use your brakes
so much that
they would get hot and no longer work well.
You can tow in DRIVE (D). You may want to shift the
transmission to THIRD
(3) or, if necessary, a lower gear
selection
if the transmission shifts too often (e.g., under
heavy loads and/or hilly conditions).
When towing at high altitude on steep uphill grades,
consider the following: Engine coolant will boil at a lower
temperature than at normal altitudes.
If you turn your
engine
off immediately after towing at high altitude
on steep uphill grades, your vehicle may show signs
similar to engine overheating.
To avoid this, let the
engine run while parked (preferably on level ground)
with the automatic transmission in PARK
(P) for a
few minutes before turning the engine
off. If you do get
the overheat warning, see
Engine Overheating on
page
5-3 1.
You really shoul tot park your vehicle, ith a
trailer attached, on a hill.
If something goes
wrong, your rig could start to move. People
can be injured, and both your vehicle and the
trailer can be damaged.
But if you ever have to park your rig on a hill, here’s
how to do it:
1. Apply your regular brakes, but don’t shift into
2. Have someone place chocks under the trailer
3. When the wheel chocks are in place, release the
4. Reapply the regular brakes. Then apply your PARK (P) yet.
wheels. regular brakes until the chocks absorb the load.
parking brake, and shift to PARK (P).
5. Release the regular brakes.
4-39

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, belt, cooling system and
brake system. Each
of these is covered in this 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.
4-40

Section 5 Service and Appearance Care
Service .......................................................... -5-3
Doing Your Own Service Work
......................... 5-3
Adding Equipment to the Outside of
Your Vehicle
.............................................. 5-4
Fuel ................................................................ 5.5
Gasoline Octane ........................................... -5-5
Gasoline Specifications .................................... 5.5
California Fuel ............................................. -56
Additives
....................................................... 5.6
Fuels in Foreign Countries
............................... 5.7
Filling Your Tank
............................................ 5-8
Filling a Portable Fuel Container
..................... 5-10
Checking Things Under the Hood .................... 5-1 1
Hood Release .............................................. 5.11
Engine Compartment Overview
...................... 5.14
Engine Oil
................................................... 5.15
Engine Cover ................. .... ........ 5.20
Engine Air Cleaner/Filter
................. ........ 5.24
Automatic Transmission Fluid
...................... 5.25
Engine Coolant ............................................. 5.28
Radiator Pressure Cap
.................................. 5.30
Engine Overheating
....................................... 5.31
Cooling System
............................................ 5.33
Engine Fan Noise
......................................... 5.39
Power Steering Fluid
..................................... 5.40
Windshield Washer Fluid
................................ 5.41 Brakes
........................................................ 5.42
Battery
........................................................ 5-46
Jump Starting
............................................... 5-47
All-Wheel Drive .............................................. 5-52
Rear Axle ....................................................... 5-53
Front Axle ...................................................... 5-54
Bulb Replacement .......................................... 5-55
Halogen Bulbs .............................. ..... 5-55
Headlamps .................................. ..... 5-55
Front Turn Signal Lamps ............................... 5-59
Replacement Bulbs
....................................... 5-61
Windshield Wiper Blade Replacement .............. 5-62
Tires .............................................................. 5.63
Inflation
- Tire Pressure ................................ 5-64
Tire Inspection and Rotation
........................... 5-64
When It
Is Time for New Tires ....................... 5-66
Buying New Tires
......................................... 5-66
Uniform Tire Quality Grading
.......................... 5-67
Wheel Alignment and Tire Balance
.................. 5-69
Wheel Replacement
...................................... 5-69
Tire Chains
.................................................. 5-70
If a Tire Goes Flat ........................................ 5.70
Changing a Flat Tire ..................................... 5.71
Compact Spare Tire ...................................... 5-82
Taillamps
.................................................... 5-60
5- 1

Fuel
Use of the recommended fuel is an important part of the
proper maintenance of your vehicle.
Gasoline Octane
Use regular unleaded gasoline with a posted octane
of
87 or higher. If the octane is less than 87, you may
get a heavy knocking noise when you drive. If this
occurs, use a gasoline rated at
87 octane or higher as
soon as possible. Otherwise, you might damage
your engine. A little pinging noise when you accelerate
or drive uphill is considered normal. This does not
indicate a problem exists or that a higher-octane fuel is
necessary.
If you are using 87 octane or higher-octane
fuel and hear heavy knocking, your engine needs
service.
Gasoline Specifications
It is recommended that gasoline meet specifications
which were developed by the American Automobile
Manufacturers Association and endorsed by the
Canadian Vehicle Manufacturers Association for better
vehicle performance and engine protection. Gasoline
meeting these specifications could provide improved
driveability and emission control system performance
compared to other gasoline.
In Canada, look for the
“Auto Makers’ Choice’’
label on the pump.
Canada Only
5-5

California Fuel Additives
If your vehicle is certified to meet California Emission
Standards (see the underhood emission control label),
it is designed to operate on fuels that meet California
specifications.
If this fuel is not available in states
adopting California emissions standards, your vehicle
will operate satisfactorily on fuels meeting federal
specifications, but emission control system performance
may be affected. The malfunction indicator lamp may
turn on (see
Malfunction Indicator Lamp on page 3-30 )
and your vehicle may fail a smog-check test. If this
occurs, return to your authorized GM dealer for
diagnosis. If it is determined that the condition is caused
by the type of fuel used, repairs may not be covered
by your warranty.
To provide cleaner air, all gasolines in the United States
are now required to contain additives that will help
prevent engine and fuel system deposits from forming,
allowing your emission control system to work
properly. You should not have
to add anything to
your fuel. Gasolines containing oxygenates, such as
ethers and ethanol, and reformulated gasolines
may be available in your area to contribute to clean air.
General Motors recommends that you use these
gasolines, particularly
if they comply with the
specifications described earlier.
Notice: Your vehicle was not designed for fuel
that contains methanol. Don’t use fuel containing
methanol. It can corrode metal parts in your fuel
system and also damage the plastic and rubber
parts. That damage wouldn’t be covered under
your warranty.
5-6

Checking Things Under
the Hood
Hood Release
Things that burn can get on hot engine parts
and start
a fire. These include liquids like fuel,
oil, coolant, brake fluid, windshield washer and
other fluids, and plastic or rubber. You or
others could be burned. Be careful not to drop
or spill things that
will burn onto a hot engine.
To open the hood, do the following:
1. Pull the handle located inside the vehicle on the
lower driver’s side of the kick panel.
5-1 1