2003 CHEVROLET ASTRO trailer

6. Start the engine and let it run until you can feel the
upper radiator hose getting hot. Watch out for the
engine cooling fan.
7. By this time, the coolant level inside the radiator
filler neck may be lower.
If the level is lower, add
more of the proper
DEX-COOL@ coolant mixture
through the filler neck until the level reaches
the base of the filler neck.
Then replace the pressure cap. At any time during
this procedure
if coolant begins to flow out of
the filler neck, reinstall the pressure cap. Be sure
the arrow on the pressure cap lines up.
Engine Fan Noise
This vehicle has a clutched engine cooling fan. When
the clutch is engaged, the fan spins faster to provide
more air to cool the engine. In most everyday driving
conditions, the clutch is not fully engaged. This improves
fuel economy and reduces fan noise. Under heavy
vehicle loading, trailer towing and/or high outside
temperatures, the fan speed increases when the clutch
engages.
So you may hear an increase in fan noise.
This is normal and should not be mistaken as the
transmission slipping or making extra shifts. It is merely
the cooling system functioning properly. The fan will
slow down when additional cooling is not required and
the clutch disengages.
You may also hear this fan noise when you start the
engine. It will go away as the fan clutch disengages.
5-39

FuseKircuit Usage
Breaker
1
2
Stop/Turn/Hazard Lamps,
Center High Mounted Stop Lamp,
Anti-Lock Brakes
Radio Accy, Rear Seat
Audio Controls
FuseKircuit
Breaker
3
4
5
6
8
9
Usage
Courtesy Lamps, Glove Box Lamp,
Dome Reading Lamps, Vanity Mirror
Lamps, Courtesy Lamps
Daytime Running Lamps Relay,
Instrument Panel Cluster
Rear Defogger
Cruise Module, Truck Body Control Module, Instrument Panel Cluster,
Cruise Control Switch,
Electrochromic Mirror
Power Outlets, DLC,
Subwoofer Amplifier
Crank Circuit Fuse, ParWNeutral
Switch, Starter Enabler Relay
License Plate Lamp, Tailamps,
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
5-94

13
14
15
16
Fuse/Circuit Usage Breaker
10 Air Bag System
11 Not Used
12 L, MI, M2 Blower Motor, Rear Air
Conditioning Relay Coil, Front Cont.
Temp. Door Motor, HI Blower Relay.
Defogger Timer Coil
Cigarette Lighter, Door Lock
Switches, Dutch Door Release Module
Cluster Illum, Climate Controls,
Chime Module, Radio Illumination,
Rear Heat Switch Illumination, Rear
Wipermasher Switch Illumination,
Rear Liftgate Switch Illumination,
Remote Cassette Illumination,
Overhead Console, Truck Body
Control Illurnination
Truck Body Module, Headlamp Relay
Front Turn Signals, Rear Turn
Signals, Trailer Turn Signals,
Back-up Lamps, Brake Transmission
Shift Interlock Solenoid 21
22
23
24
A
19
20
FuseKircuit
Usage
Breaker
17 Front Wipers, Front Washer Pump
18 VCM-lgn
3, VCM-Brake, Cruise
Stepper Motor Signal, ATC Module
Instrument Panel Radio: ATC
(Main Feed),
2000 Series (Standby)
PRNDUOdometer, TCC Enable and
PWM Solenoid, Shift A and Shift B
Solenoids, 3-2 Downshift Solenoid, Instrument Panel Cluster, VCM
Module
Powr Adjust Mirrors
Not Used
Rear Wiper, Rear Washer Pump
Not Used
(Circuit Breaker) Power Door Lock
Relay, 6-Way Power Seats
(Circuit Breaker) Power Windows
B
5-95

Usage
Rear/Heat and Air Conditioning
Relays
AIC Relay
(Rear Heat
and AIC)
Relay
Relay
A/C Enable
Relay
Upfitter-ACCY
Upfitter Accessory
Starter Enable Starter
Headlamps Relay
Fuel Pump
Relay Air
Conditioning
Headlamps
Fuel Pump
FuselCircuit
Usage
UPFITTER- Upfitter Battery Power Stud,
BATT Trailer Wiring Harness
UPFITTER- Upfitter Accessory Relay
ACCY
Spare Not used
Spare Not used
Breaker FuselCircuit
Breaker
Spare
ECM-1 B
HORN
AIC COMP
RR HTR/AC ATC
FRT HVAC
ENG-I
IGN-E
ECM-I
Blank
RH HDLMP
LH Headlamp
Blank
Blank
Usage
Not used
Fuel Pump Relay and Motor, VCM,
Oil Pressure Switch/Sender
Horn Relay and Horn
Air Conditioning Enable Relay and
Compressor
Rear Heater and Air Conditioning
Active Transfer Case-L Van
Front Heater and Air Conditioning
Oxygen Sensors, Camshaft Position
Sensor, Mass Air Flow Sensor,
Evaporative Emission Canister
Vent Solenoid
Air Conditioning Enable Relay Coil
Fuel Injectors
1-6, Crankshaft
Position Sensot, VCM, Coil Driver
Module (EST), Ignition Coil
Not Used
Right Headlamp
Left Headlamp
Not Used
Not Used
5-97

Selecting the Right Schedule
First you’ll need to decide which of the two schedules
is right for your vehicle. Here’s how to decide which
schedule to follow:
Short Trip/City Definition
Follow the Short Trip/City Scheduled Maintenance if any
one of these conditions is true for your vehicle:
e
e
e
e
Most trips are less than 5 miles (8 km). This is
particularly important when outside temperatures
are below freezing.
Most trips include extensive idling (such as frequent
driving in stop-and-go traffic).
You frequently tow a trailer or use a carrier on top
of your vehicle.
If the vehicle is used for delivery service, police,
taxi or other commercial application.
One of the reasons you should follow this schedule if
you operate your vehicle under any of these conditions
is that these conditions cause engine oil to break
down sooner.
Short Trip/City Intervals
Every 3,000 Miles (5 000 km): Engine Oil and Filter
Change (or
3 months, whichever occurs first). Chassis
Lubrication (or
3 months, whichever occurs first).
Drive Axle Fluid Check.
Every 6,000 Miles (IO 000 km): Tire Rotation.
Every 15,000 Miles (25 000 km): Engine Air
Cleaner Filter Inspection,
if driving in dusty conditions.
Front Wheel Bearing Repack (two-wheel drive only)
(or at each brake relining, whichever occurs first).
Automatic Transmission Service (severe conditions only).
Every 30,000 Miles (50 000 km): Engine Air Cleaner
Filter Replacement. Fuel Filter Replacement.
Every 50,000 Miles (83 000 km): Automatic
Transmission Service (normal conditions).
Transfer Case Fluid Change.
Every 100,000 Miles (166 000 km): Spark Plug Wire
Inspection. Spark Plug Replacement. Positive
Crankcase Ventilation (PCV) Valve Inspection.
Every 150,000 Miles (240 000 km): Cooling System
Service (or every
60 months, whichever occurs
first). Engine Accessory Drive Belt Inspection.
These intervals only summarize maintenance services.
Be sure to follow the complete scheduled maintenance
on the following pages.
6-5

Long Trip/Highway Definition
Follow this scheduled maintenance only if none of
the conditions from the Short Trip/City Scheduled
Maintenance are true. Do not use this schedule
if the
vehicle is used for trailer towing, driven in a dusty area
or used
off paved roads. Use the Short Trip/City
schedule for these conditions.
Driving a vehicle with a fully warmed engine under
highway conditions will cause engine oil
to break
down slower.
Long Trip/Highway Intervals
Every 7,500 Miles (12 500 km): Engine Oil and Filter
Change (or every
12 months, whichever occurs first).
Chassis Lubrication (or
12 months, whichever
occurs first). Drive Axle Fluid Check. Tire Rotation.
Every 15,000 Miles (25 000 km): Automatic
Transmission Service (severe conditions only).
Every 30,000 Miles (50 000 km): Fuel Filter
Replacement. Engine Air Cleaner Filter Replacement.
Front Wheel Bearing Repack (two-wheel drive only)
(or at each brake relining, whichever occurs first).
Every 50,000 Miles (83 000 km): Automatic
Transmission Service (normal conditions).
Transfer Case Fluid Change.
Every 100,000 Miles (166 000 km): Spark Plug Wire
Inspection. Spark Plug Replacement. Positive
Crankcase Ventilation (PCV) Valve Inspection.
Every 150,000 Miles (240 000 km): Cooling System
Service (or every
60 months, whichever occurs first).
Engine Accessory Drive Belt Inspection.
These intervals only summarize maintenance services.
Be sure to follow the complete scheduled maintenance
on the following pages.
6-6

12,000 Miles (20 000 km)
0 Change engine oil and filter (or every 3 months,
0 Lubricate chassis components (or every 3 months,
0 Check readfront axle fluid level and add fluid as
whichever
occurs first).
An Emission Control Service.
whichever occurs first). (See footnote #.)
needed. Check constant velocity joints and axle seals
for leaking.
page 5-64 for proper rotation pattern and additional
information.
(See footnote +.)
0 Rotate tires. See Tire lnspection and Rotation on
15,000 Miles (25 000 km)
0 Change engine oil and filter (or every 3 months,
whichever occurs first).
An Emission Control Service.
0 Lubricate chassis components (or every 3 months,
whichever occurs first).
(See footnote #.)
CI Inspect engine air cleaner filter if you are driving in
dusty conditions. Replace filter
if necessary.
An Emission Control Service. (See footnote t.)
0 Check readfront axle fluid level and add fluid as
needed. Check constant velocity joints and axle seals
for leaking.
0 For Two-Wheel-Drive vehicles only: Clean and repack
the front wheel bearings (or at each brake relining,
whichever occurs first).
0 Change automatic transmission fluid and filter if the
vehicle
is mainly driven under one or more of these
conditions:
- In heavy city traffic where the outside
temperature regularly reaches
90°F (32°C)
or higher.
- In hilly or mountainous terrain.
- When doing frequent trailer towing.
- Uses such as found in taxi, police or delivery
service.
If you do not use your vehicle under any of these
conditions, change the fluid and filter every
50,000 miles (83 000 km).
18,000 Miles (30 000 km)
0 Change engine oil and filter (or every 3 months,
whichever occurs first).
An Emission Control Service.
0 Lubricate chassis components (or every 3 months,
0 Check readfront axle fluid level and add fluid as
whichever
occurs first).(See
footnote #.)
needed. Check constant velocity joints and axle seals
for leaking.
0 Rotate tires. See Tire lnspection and Rotation on
page
5-64 for proper rotation pattern and additional
information.
(See footnote +.)
6-8

0 Change automatic transmission fluid and filter if the
vehicle is mainly driven under one or more of these
conditions:
- In heavy city traffic where the outside
temperature regularly reaches
90°F (32°C)
or higher.
- In hilly or mountainous terrain.
- When doing frequent trailer towing.
- Uses such as found in taxi, police or delivery
service.
If you do not use your vehicle under any of these
conditions, change the fluid and filter every
50,000 miles (83 000 km),
U Rotate tires. See Tire Inspection and Rotation on
page 5-64
for proper rotation pattern and additional
information.
(See footnote +.)
33,000 Miles (55 000 km)
0 Change engine oil and filter (or every 3 months,
whichever occurs first).
An Emission Control Service.
0 Lubricate chassis components (or every 3 months,
whichever occurs first).
(See footnote #.)
36,000 Miles (60 000 km)
D Change engine oil and filter (or every 3 months,
whichever occurs first).
An Emission Control Service.
U Lubricate chassis components (or every 3 months,
0 Rotate tires. See Tire Inspection and Rotation on
whichever occurs first). (See footnote #.)
page 5-64 for proper rotation pattern and additional
information.
(See footnote +.)
needed. Check constant velocity joints and axle seals
for leaking.
0 Check readfront axle fluid level and add fluid as
39,000 Miles (65 000 km)
0 Change engine oil and filter (or every 3 months,
0 Lubricate chassis components (or every 3 months,
tl Check readfront axle fluid level and add fluid as
whichever
occurs first).
An Emission Control Service.
whichever occurs first). (See footnote #.)
needed. Check constant velocity joints and axle seals
for leaking.
0 Check readfront axle fluid level and add fluid as
needed. Check constant velocity joints and axle seals
for leaking.
6-1 0