light CHEVROLET ASTRO CARGO VAN 2004 2.G Repair Manual

(A) Light Truck (LT-Metric) Tire:The United States
version of a metric tire sizing system. The letter “LT”
as the rst two characters in the tire size means a light
truck tire engineered to standards set by the U. S.
Tire and Rim Association.
(B) Tire Width:The three-digit number indicates the
tire section width in millimeters from sidewall to sidewall.(C) Aspect Ratio:A two-digit number that indicates
the tire height-to-width measurements. For example,
if the tire size aspect ratio is “75,” as shown in item “C”
of the illustration, it would mean that the tire’s sidewall
is 75% as high as it is wide.
(D) Construction Code:A letter code is used to
indicate the type of ply construction in the tire. The letter
“R” means radial ply construction; the letter “D” means
diagonal or bias ply construction; and the letter “B”
means belted-bias ply construction.
(E) Rim Diameter:Diameter of the wheel in inches.
(F) Service Description:The service description
indicates the load range and speed rating of a tire.
The load index can range from 1 to 279. Speed ratings
range from “A” to “Z”. The light truck tire size example
above shows dual or single tire congurations. Light Truck (LT-Metric) Tire
5-67

Tire Terminology and Denitions
Air Pressure:The amount of air inside the tire pressing
outward on each square inch of the tire. Air pressure
is expressed in pounds per square inch (psi) or
kilopascal (kPa).
Accessory Weight:This means the combined weight
of optional accessories. Some examples of optional
accessories are, automatic transmission, power steering,
power brakes, power windows, power seats, and air
conditioning.
Aspect Ratio:The relationship of a tire’s height to
its width.
Belt:A rubber coated layer of cords that is located
between the plies and the tread. Cords may be made
from steel or other reinforcing materials.
Bead:The tire bead contains steel wires wrapped by
steel cords that hold the tire onto the rim.
Bias Ply Tire:A pneumatic tire in which the plies are
laid at alternate angles less than 90 degrees to the
centerline of the tread.
Cold Ination Pressure:The amount of air pressure
in a tire, measured in pounds per square inch (psi)
or kilopascals (kPa) before a tire has built up heat from
driving. SeeInation - Tire Pressure on page 5-70.Curb Weight:This means the weight of a motor
vehicle with standard and optional equipment including
the maximum capacity of fuel, oil and coolant, but
without passengers and cargo.
DOT Markings:A code molded into the sidewall of a
tire signifying that the tire is in compliance with the
U.S. Department of Transportation motor vehicle safety
standards. The DOT code includes the Tire Identication
Number (TIN), an alphanumeric designator which can
also identify the tire manufacturer, production plant,
brand and date of production.
GVWR:Gross Vehicle Weight Rating, seeLoading
Your Vehicle on page 4-29.
GAWR FRT:Gross Axle Weight Rating for the front
axle, seeLoading Your Vehicle on page 4-29.
GAWR RR:Gross Axle Weight Rating for the rear axle,
seeLoading Your Vehicle on page 4-29.
Intended Outboard Sidewall:The side of an
asymmetrical tire, that must always face outward when
mounted on a vehicle.
Kilopascal (kPa):The metric unit for air pressure.
There are 6.9 kPa’s to one psi.
Light Truck (LT-Metric) Tire:A tire used on light duty
trucks and some multipurpose passenger vehicles.
5-68

Load Index:An assigned number ranging from
1 to 279 that corresponds to the load carrying capacity
of a tire.
Maximum Ination Pressure:The maximum air
pressure to which a cold tire may be inated. The
maximum air pressure is molded onto the sidewall.
Maximum Load Rating:The load rating for a tire at the
maximum permissible ination pressure for that tire.
Maximum Loaded Vehicle Weight:The sum of curb
weight; accessory weight; vehicle capacity weight;
and production options weight.
Normal Occupant Weight:The number of occupants
a vehicle is designed to seat multiplied by 150 pounds
(68 kg). SeeLoading Your Vehicle on page 4-29.
Occupant Distribution:Designated seating positions.
Outward Facing Sidewall:The side of a asymmetrical
tire that has a particular side that faces outward
when mounted on a vehicle. The side of the tire that
contains a whitewall, bears white lettering or bears
manufacturer, brand and or model name molding that
is higher or deeper than the same moldings on the
other sidewall of the tire.
Passenger (P-Metric) Tire:A tire used on
passenger cars and some light duty trucks and
multipurpose vehicles.Recommended Ination Pressure:Vehicle
manufacturer’s recommended tire ination pressure and
shown on the tire placard. SeeInation - Tire Pressure
on page 5-70andLoading Your Vehicle on page 4-29.
Radial Ply tire:A pneumatic tire in which the ply cords
that extend to the beads are laid at 90 degrees to the
centerline of the tread.
Rim:A metal support for a tire and upon which the tire
beads are seated.
Sidewall:The portion of a tire between the tread and
the bead.
Speed Rating:An alphanumeric code assigned to
a tire indicating the maximum speed at which a tire
can operate.
Traction:The friction between the tire and the road
surface. The amount of grip provided.
Tread:The portion of a tire that comes into contact
with the road.
Treadwear Indicators:Narrow bands, sometimes
called “wear bars,” that show across the tread of a tire
when only 2/32 inch of tread remains. SeeWhen It
Is Time for New Tires on page 5-72.
5-69

Uniform Tire Quality Grading
Quality grades can be found where applicable on the
tire sidewall between tread shoulder and maximum
section width. For example:
Treadwear 200 Traction AA Temperature A
The following information relates to the system
developed by the United States National Highway
Traffic Safety Administration, which grades tires by
treadwear, traction and temperature performance.
(This applies only to vehicles sold in the United States.)
The grades are molded on the sidewalls of most
passenger car tires. The Uniform Tire Quality Grading
system does not apply to deep tread, winter-type
snow tires, space-saver or temporary use spare tires,
tires with nominal rim diameters of 10 to 12 inches
(25 to 30 cm), or to some limited-production tires.
While the tires available on General Motors passenger
cars and light trucks may vary with respect to these
grades, they must also conform to federal safety
requirements and additional General Motors Tire
Performance Criteria (TPC) standards.
Treadwear
The treadwear grade is a comparative rating based on
the wear rate of the tire when tested under controlled
conditions on a specied government test course.
For example, a tire graded 150 would wear one and
a half (1.5) times as well on the government course as
a tire graded 100. The relative performance of tires
depends upon the actual conditions of their use,
however, and may depart signicantly from the norm
due to variations in driving habits, service practices and
differences in road characteristics and climate.
Traction – AA, A, B, C
The traction grades, from highest to lowest, are AA, A,
B, and C. Those grades represent the tire’s ability
to stop on wet pavement as measured under controlled
conditions on specied government test surfaces of
asphalt and concrete. A tire marked C may have poor
traction performance. Warning: The traction grade
assigned to this tire is based on straight-ahead braking
traction tests, and does not include acceleration,
cornering, hydroplaning, or peak traction characteristics.
5-74

Vehicle Care/Appearance Materials
See your GM dealer for more information on purchasing
the following products.
Description Usage
Polishing Cloth
Wax-TreatedInterior and exterior
polishing cloth.
Tar and Road Oil
RemoverRemoves tar, road oil
and asphalt.
Chrome Cleaner
and PolishUse on chrome or
stainless steel.
White Sidewall
Tire CleanerRemoves soil and black
marks from whitewalls.
Vinyl CleanerCleans vinyl tops,
upholstery and
convertible tops.
Glass CleanerRemoves dirt, grime,
smoke and ngerprints.
Chrome and Wire
Wheel CleanerRemoves dirt and grime
from chrome wheels
and wire wheel covers.
Finish EnhancerRemoves dust,
ngerprints, and surface
contaminants. Spray on
wipe off.
Description Usage
Swirl Remover PolishRemoves swirl marks,
ne scratches and
other light surface
contamination.
Cleaner WaxRemoves light scratches
and protects nish.
Foaming Tire Shine
Low GlossCleans, shines and
protects in one easy step,
no wiping necessary.
Wash Wax ConcentrateMedium foaming
shampoo. Cleans and
lightly waxes.
Biodegradable and
phosphate free.
Spot LifterQuickly and easily
removes spots and stains
from carpets, vinyl and
cloth upholstery.
Odor EliminatorOdorless spray odor
eliminator used on fabrics,
vinyl, leather and carpet.
See your General Motors parts department for these
products. SeePart D: Recommended Fluids and
Lubricants on page 6-28.
5-98

Fuses and Circuit Breakers
The wiring circuits in your vehicle are protected from
short circuits by a combination of fuses, circuit breakers
and fusible thermal links. This greatly reduces the
chance of res caused by electrical problems.
Look at the silver-colored band inside the fuse. If the
band is broken or melted, replace the fuse. Be sure you
replace a bad fuse with a new one of the identical
size and rating.
Spare fuses and a fuse puller are located in the
underhood fuse block. You can remove fuses with the
fuse puller. Remember to replace any of the spare
fuses you use, so you will have some if you ever need
them again.
If you ever have a problem on the road and don’t have
a spare fuse, you can borrow one that has the same
amperage. Just pick some feature of your vehicle
that you can get along without — like the radio or
cigarette lighter — and use its fuse, if it is the correct
amperage. Replace it as soon as you can.
There are two fuse blocks in your vehicle: one is inside
the vehicle and one is in the engine compartment.
Instrument Panel Fuse Block
The fuse block is located on the lower portion of the
instrument panel on the driver’s side.
5-101

Fuse/Circuit
BreakerUsage
1Stop/Turn/Hazard Lamps,
Center High Mounted Stop Lamp,
Anti-Lock Brakes
2Radio Accessory, Rear Seat
Audio Controls
Fuse/Circuit
BreakerUsage
3Courtesy Lamps, Glove Box Lamp,
Dome Reading Lamps, Vanity
Mirror Lamps, Courtesy Lamps
4Daytime Running Lamps Relay,
Instrument Panel Cluster
5 Rear Defogger
6Cruise Module, Truck Body
Control Module, Instrument Panel
Cluster, Cruise Control Switch,
Electrochromic Mirror
7 Power Outlets, Subwoofer Amplier
8Crank Circuit Fuse, Park/Neutral
Switch, Starter Enabler Relay
9License Plate Lamp, Taillamps,
Parking Lamps, Ashtray Lamp,
Panel Lights, Trailer Taillamps,
Front and Rear Sidemarker
Lamps, Door Switch Illumination,
Headlamp Switch Illumination,
Rear Seat Audio Illumination,
Truck Body Control Module
10 Air Bag System
5-102

Fuse/Circuit
BreakerUsage
11 Not Used
12Blower Motor, Rear Air Conditioning
Relay Coil, Front Cont. Temp.
Door Motor, HI Blower Relay,
Defogger Timer Coil
13Cigarette Lighter, Door Lock
Switches, Dutch Door
Release Module
14Cluster Illumination, Climate
Controls, Chime Module, Radio
Illumination, Rear Heat Switch
Illumination, Rear Wiper/Washer
Switch Illumination, Rear Liftgate
Switch Illumination, Remote
Cassette Illumination,
Overhead Console, Truck Body
Control Illumination
15Truck Body Module,
Headlamp Relay
16Front Turn Signals, Rear
Turn Signals, Trailer Turn
Signals, Back-Up Lamps,
Brake Transmission Shift
Interlock SolenoidFuse/Circuit
BreakerUsage
17 Front Wipers, Front Washer Pump
18VCM-Ign 3, VCM-Brake,
Cruise Stepper Motor Signal,
ATC Module
19Instrument Panel Radio: ATC
(Main Feed), 2000 Series (Standby)
20PRNDL/Odometer, Shift A and
Shift B Solenoids, 3–2 Downshift
Solenoid, Instrument Panel Cluster,
VCM Module
21 Powr Adjust Mirrors
22 Not Used
23 Rear Wiper, Rear Washer Pump
24 Not Used
A(Circuit Breaker) Power Door
Lock Relay, 6–Way Power Seats
B (Circuit Breaker) Power Windows
5-103

Fuse/Circuit
BreakerUsage
ENG-IOxygen Sensors, Camshaft Position
Sensor, Mass Air Flow Sensor,
Evaporative Emission Canister
Vent Solenoid
IGN-E Air Conditioning Enable Relay Coil
ECM-IFuel Injectors 1–6, Crankshaft
Position Sensot, VCM, Coil Driver
Module (EST), Ignition Coil
Blank Not Used
RH HDLMP Right Headlamp
LH Headlamp Left Headlamp
Blank Not Used
Blank Not Used
DIODE-1 Air Conditioning
Blank Not Used
Blank Not UsedFuse/Circuit
BreakerUsage
Blank Not Used
LIGHTINGCourtesy Fuse, Power Adjust
Mirrors Fuse, Truck Body Control
Battery Fuse
BATTPower Accessory Circuit Breaker,
Stop/Hazard Fuse, Auxiliary Power
Fuse, Cigarette Lighter Fuse,
Radio Battery Fuse
IGN A Starter Relay, Ignition Switch
IGN B Ignition Switch
ABSElectronic Brake
Control Module
Blank Not Used
RAPRadio Accessory,
Power Windows
HTD MIR/RR
DEFOGRear Window Defogger,
Climate Control Head
5-106

Part B: Owner Checks and Services
Listed in this part are owner checks and services
which should be performed at the intervals specied
to help ensure the safety, dependability and emission
control performance of your vehicle.
Be sure any necessary repairs are completed at once.
Whenever any uids or lubricants are added to your
vehicle, make sure they are the proper ones, as
shown in Part D.
At Each Fuel Fill
It is important for you or a service station attendant
to perform these underhood checks at each fuel ll.
Engine Oil Level Check
Check the engine oil level and add the proper oil
if necessary. SeeEngine Oil on page 5-13for
further details.
Engine Coolant Level Check
Check the engine coolant level and add DEX-COOL®
coolant mixture if necessary. SeeEngine Coolant
on page 5-26for further details.
Windshield Washer Fluid Level Check
Check the windshield washer uid level in the windshield
washer tank and add the proper uid if necessary. See
Windshield Washer Fluid on page 5-39for further details.
At Least Once a Month
Tire Ination Check
Visually inspect your tires and make sure tires are inated
to the correct pressures. Do not forget to check your
spare tire. SeeTires on page 5-60for further details.
At Least Twice a Year
Restraint System Check
Make sure the safety belt reminder light and all your belts,
buckles, latch plates, retractors and anchorages are
working properly. Look for any other loose or damaged
safety belt system parts. If you see anything that might
keep a safety belt system from doing its job, have it
repaired. Have any torn or frayed safety belts replaced.
Also look for any opened or broken air bag coverings,
and have them repaired or replaced. (The air bag
system does not need regular maintenance.)
6-22