2004 CHEVROLET ASTRO trailer

How to Check
Because this operation can be a little difficult, you may
choose to have this done at the dealership service
department.
If you do it yourself, be sure to follow all the instructions
here, or you could get a false reading on the dipstick.
Notice:Too much or too little ¯uid can damage
your transmission. Too much can mean that some
of the ¯uid could come out and fall on hot engine
part or exhaust system parts, starting a ®re.
Too little ¯uid could cause the transmission to
overheat. Be sure to get an accurate reading if you
check your transmission ¯uid.
Wait at least 30 minutes before checking the
transmission ¯uid level if you have been driving:
·When outside temperatures are above 90ÉF (32ÉC).
·At high speed for quite a while.
·In heavy traffic ± especially in hot weather.
·While pulling a trailer.To get the right reading, the ¯uid should be at normal
operating temperature, which is 180ÉF to 200ÉF
(82ÉC to 93ÉC).
Get the vehicle warmed up by driving about 15 miles
(24 km) when outside temperatures are above 50ÉF
(10ÉC). If it's colder than 50ÉF (10ÉC), drive the vehicle
in DRIVE (D) until the engine temperature gage
moves and then remains steady for 10 minutes.
A cold ¯uid check can be made after the vehicle has
been sitting for eight hours or more with the engine off,
but this is used only as a reference. Let the engine
run at idle for ®ve minutes if outside temperatures are
50ÉF (10ÉC) or more. If it's colder than 50ÉF (10ÉC), you
may have to idle the engine longer. Should the ¯uid
level be low during this cold check, you
mustcheck the
¯uid hot before adding ¯uid. Checking the ¯uid hot
will give you a more accurate reading of the ¯uid level.
5-23

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. See²Driving on Gradesº inTowing a
Trailer on page 4-35
.
If you get the overheat warning with no sign of steam,
try this for a minute or so:
1. In heavy traffic, let the engine idle in NEUTRAL (N)
while stopped. If it is safe to do so, pull off the road,
shift to PARK (P) or NEUTRAL (N) and let the
engine idle.
2. Turn on your heater to full hot at the highest fan
speed and open the window as necessary.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 and you have not stopped, pull
over, stop, and park your vehicle right away.
If there's still no sign of steam, you can 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 vehicleuntil it
cools down.
You may decide not to lift the hood but to get service
help right away.
5-29

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
®ller neck may be lower. If the level is lower, add
more of the proper DEX-COOL
žcoolant mixture
through the ®ller neck until the level reaches
the base of the ®ller neck.
Then replace the pressure cap. At any time during
this procedure if coolant begins to ¯ow out of
the ®ller 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.
5-36

Fuse/Circuit
Breaker Usage
3 Courtesy Lamps, Glove Box Lamp,
Dome Reading Lamps, Vanity Mirror
Lamps, Courtesy Lamps
4 Daytime Running Lamps Relay,
Instrument Panel Cluster
5 Rear Defogger
6 Cruise Module, Truck Body Control
Module, Instrument Panel Cluster,
Cruise Control Switch,
Electrochromic Mirror
7 Power Outlets, Subwoofer Ampli®er
8 Crank Circuit Fuse, Park/Neutral
Switch, Starter Enabler Relay
9 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
10 Air Bag System
11 Not UsedFuse/Circuit
Breaker Usage
12 Blower Motor, Rear Air Conditioning
Relay Coil, Front Cont. Temp. Door
Motor, HI Blower Relay, Defogger
Timer Coil
13 Cigarette Lighter, Door Lock
Switches, Dutch Door Release
Module
14 Cluster 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
15 Truck Body Module, Headlamp
Relay
16 Front Turn Signals, Rear Turn
Signals, Trailer Turn Signals,
Back-Up Lamps, Brake
Transmission Shift Interlock Solenoid
17 Front Wipers, Front Washer Pump
5-98

Feed Usage
AUX B Up®tter Battery Feed
AUX A Up®tter Accessory Feed
Relays Usage
A/C Relay
(Rear Heat
and A/C)Rear/Heat and Air ConditioningRelays Usage
Up®tter-ACCY
RelayUp®tter Accessory
Starter Enable
RelayStarter
A/C Enable
RelayAir Conditioning
Headlamps
RelayHeadlamps
Fuel Pump
RelayFuel Pump
Fuse/Circuit
BreakerUsage
UPFITTER-
BATTUp®tter Battery Power Stud, Trailer
Wiring Harness
UPFITTER-
ACCYUp®tter Accessory Relay
Spare Not used
Spare Not used
Spare Not used
ECM-1BFuel Pump Relay and Motor, VCM,
Oil Pressure Switch/Sender
HORN Horn Relay and Horn
5-100

Selecting the Right Schedule
First you will need to decide which of the two schedules
is right for your vehicle. Here is how to decide which
schedule to follow:
Short Trip/City De®nition
Follow the Short Trip/City Scheduled Maintenance if any
one of these conditions is true for your vehicle:
·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 ®rst). Chassis
Lubrication (or 3 months, whichever occurs ®rst).
Drive Axle Fluid Check.
Every 6,000 Miles (10 000 km):Tire Rotation.
Every 15,000 Miles (25 000 km):Engine Air Cleaner
Filter Inspection. Front Wheel Bearing Repack
(two±wheel drive only) (or at each brake relining,
whichever occurs ®rst). 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
®rst). 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 De®nition
Follow this scheduled maintenanceonlyif 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
®rst). Chassis Lubrication (or 12 months, whichever
occurs ®rst). Drive Axle Fluid Check. Tire Rotation.
Every 15,000 Miles (25 000 km):Engine Air Cleaner
Filter Inspection. 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 ®rst).
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
®rst). Engine Accessory Drive Belt Inspection.
These intervals only summarize maintenance services.
Be sure to follow the complete scheduled maintenance
on the following pages.
Short Trip/City Scheduled
Maintenance
The services shown in this schedule up to 100,000 miles
(166 000 km) should be repeated after 100,000 miles
(166 000 km) at the same intervals for the life of
this vehicle. The services shown at 150,000 miles
(240 000 km) should be repeated at the same interval
after 150,000 miles (240 000 km) for the life of this
vehicle.
See
Part B: Owner Checks and Services on page 6-24andPart C: Periodic Maintenance Inspections on
page 6-28.
6-6

15,000 Miles (25 000 km)
qChange engine oil and ®lter (or every 3 months,
whichever occurs ®rst).An Emission Control Service.
qLubricate chassis components (or every 3 months,
whichever occurs ®rst).(See footnote #.)
qInspect engine air cleaner ®lter. If necessary, replace
the ®lter. If vehicle is driven in dusty/dirty conditions,
inspect ®lter at every engine oil change. See
Engine Air Cleaner/Filter on page 5-20for more
information.An Emission Control Service. (See
footnote ².)
qFor Two-Wheel-Drive vehicles only: Clean and
repack the front wheel bearings (or at each
brake relining, whichever occurs ®rst).
qChange automatic transmission ¯uid and ®lter if the
vehicle is mainly driven under one or more of these
conditions:
þ In heavy city traffic where the outside
temperature regularly reaches 90ÉF (32ÉC) or
higher.
þ In hilly or mountainous terrain.
þ When doing frequent trailer towing.
þ Uses such as found in taxi, police or delivery
service.
If you do not use your vehicle under any of these
conditions, change the ¯uid and ®lter every 50,000 miles
(83 000 km).
18,000 Miles (30 000 km)
qChange engine oil and ®lter (or every 3 months,
whichever occurs ®rst).An Emission Control Service.
qLubricate chassis components (or every 3 months,
whichever occurs ®rst).(See footnote #.)
qRotate tires. SeeTire Inspection and Rotation on
page 5-62for proper rotation pattern and additional
information.(See footnote +.)
21,000 Miles (35 000 km)
qChange engine oil and ®lter (or every 3 months,
whichever occurs ®rst).An Emission Control Service.
qLubricate chassis components (or every 3 months,
whichever occurs ®rst).(See footnote #.)
24,000 Miles (40 000 km)
qChange engine oil and ®lter (or every 3 months,
whichever occurs ®rst).An Emission Control Service.
qLubricate chassis components (or every 3 months,
whichever occurs ®rst).(See footnote #.)
qRotate tires. SeeTire Inspection and Rotation on
page 5-62for proper rotation pattern and additional
information.(See footnote +.)
6-8