2003 BUICK CENTURY heating

Engine Coolant
The cooling system in your vehicle is ®lled with
DEX-COOLžengine coolant. This coolant is designed
to remain in your vehicle for 5 years or 150,000 miles
(240 000 km), whichever occurs ®rst, if you add
only DEX-COOL
žextended life coolant.
The following explains your cooling system and how to
add coolant when it is low. If you have a problem
with engine overheating or if you need to add coolant to
your radiator, see
Engine Overheating on page 5-26.
A 50/50 mixture of clean, drinkable water and
DEX-COOL
žcoolant will:
·Give freezing protection down to-34ÉF (-37ÉC).
·Give boiling protection up to 265ÉF (129ÉC).
·Protect against rust and corrosion.
·Help keep the proper engine temperature.
·Let the warning lights and gages work as they
should.
Notice:When adding coolant, it is important that
you use only DEX-COOLž(silicate-free) coolant.
If coolant other than DEX-COOLžis added to
the system, premature engine, heater core or
radiator corrosion may result. In addition, the engine
coolant will require change sooner Ð at 30,000 miles
(50,000 km) or 24 months, whichever occurs ®rst.
Damage caused by the use of coolant other
than DEX-COOL
žis not covered by your new vehicle
warranty.
5-23

Radiator Pressure Cap
Notice:Your radiator cap is a pressure-type cap
and must be tightly installed to prevent coolant loss
and possible engine damage from overheating.
Be sure the arrows on the cap line up with the
over¯ow tube on the radiator ®ller neck.
The radiator pressure cap is located near the front of
the engine compartment on the passenger's side of the
vehicle. See
Engine Compartment Overview on
page 5-12for more information on location.
Engine Overheating
You will ®nd a coolant temperature gage and a hot
engine warning light on your instrument panel.
See
Engine Coolant Temperature Gage on page 3-30andEngine Coolant Temperature Warning Light on
page 3-29.
Overheated Engine Protection
Operating Mode
The emergency engine protection operating mode
allows your vehicle to be driven to a safe place in an
emergency situation. If an overheated engine condition
exists, this protection mode alternates ®ring groups
of cylinders to help prevent engine damage. In
this mode, you will notice a signi®cant loss in power and
engine performance. The engine coolant temperature
gage indicator will move to the red area, showing that an
overheated engine condition exists. Driving extended
miles (km) and/or towing a trailer in the overheated
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, change the oil and reset the oil
life system. See ªEngine Oilº in the Index.
5-26

When the engine is cold,
the coolant level should be
at or above the COLD
mark on the coolant
recovery tank. If it isn't,
you may have a leak at the
pressure cap or in the
radiator hoses, heater
hoses, radiator, water
pump or somewhere else
in the cooling system.
{CAUTION:
Heater and radiator hoses, and other engine
parts, can be very hot. Don't touch them. If you
do, you can be burned.
Don't run the engine if there is a leak. If you
run the engine, it could lose all coolant. That
could cause an engine ®re, and you could be
burned. Get any leak ®xed before you drive the
vehicle.If there seems to be no leak, with the engine on, check
to see if the electric engine cooling fans are running.
If the engine is overheating, both fans should be
running. If they aren't, your vehicle needs service.
Notice:Engine damage from running your engine
without coolant isn't covered by your warranty.
See ªOverheated Engine Protection Operating
Modeº in the Index for information on driving to a
safe place in an emergency.
Notice:When adding coolant, it is important that
you use only DEX-COOLž(silicate-free) coolant.
If coolant other than DEX-COOLžis added to
the system, premature engine, heater core or
radiator corrosion may result. In addition, the engine
coolant will require change sooner Ð at 30,000 miles
(50 000 km) or 24 months, whichever occurs ®rst.
Damage caused by the use of coolant other
than DEX-COOL
žis not covered by your new vehicle
warranty.
5-30

Tires
Your new vehicle comes with high-quality tires made by
a leading tire manufacturer. If you ever have questions
about your tire warranty and where to obtain service,
see your Buick Warranty booklet for details.
{CAUTION:
Poorly maintained and improperly used tires
are dangerous.
·Overloading your tires can cause
overheating as a result of too much
friction. You could have an air-out and a
serious accident. See ªLoading Your
Vehicleº in the Index.
·Underin¯ated tires pose the same danger
as overloaded tires. The resulting accident
could cause serious injury. Check all tires
frequently to maintain the recommended
pressure. Tire pressure should be checked
when your tires are cold.
CAUTION: (Continued)
CAUTION: (Continued)
·
Overin¯ated tires are more likely to be cut,
punctured or broken by a sudden
impact Ð such as when you hit a pothole.
Keep tires at the recommended pressure.
·Worn, old tires can cause accidents. If
your tread is badly worn, or if your tires
have been damaged, replace them.
In¯ation Ð Tire Pressure
The Tire-Loading Information label, which is on the
inside of the trunk lid, shows the correct in¯ation
pressures for your tires when they're cold. ªColdº means
your vehicle has been sitting for at least three hours
or driven no more than 1 mile (1,6 km).
5-57

Circuit
BreakersUsage
POWER
SEATSPower Seats
Blank Not Used
Fuses Usage
PARK LOCK Ignition Key Solenoid
Blank Not Used
Blank Not Used
PCM, BCM,
U/H RELAYIgnition Signal: Hot in Run and Start,
Powertrain Control Module, Body
Control Module, Underhood Relay
RADIO PREM.
SOUNDRemote Radio Premium Sound
POWER
MIRRORSPower Mirrors
Blank Not Used
PANEL
DIMMINGPanel Dimming
Blank Not Used
IGN 0,
CLUSTER,
PCM, BCMIgnition Signal: Hot in Run, Unlock
and Start, Cluster, Powertrain
Control Module, Body Control
Module
Blank Not Used
Fuses Usage
Blank Not Used
Blank Not Used
INADV POWER
BUSInterior Lamps
DOOR LOCKS Door Locks
Blank Not Used
TAIL LAMPS,
LIC LAMPSTaillamps, License Plate Lamps
RADIO Radio
HEATED
MIRRORNot Used
CRUISE Cruise Control
Blank Not Used
CLUSTER Instrument Panel Cluster
CIGAR LTR Cigarette Lighter
STOP LAMPS Stoplamps
ONSTAR OnStar
ž
FRT PARK LPS Front Parking Lamps
Blank Not Used
CRANK
SIGNAL, BCM,
CLUSTERCrank Signal, Body Control Module,
Cluster, Powertrain Control Module
HVACIgnition Signal, Heating Ventilation
Air Conditioning Control Head
5-90

Fuses Usage
BTSI PARK
LOCKShifter Lock Solenoid
AIR BAG Air Bag
BCM PWR Body Control Module
HAZARD Hazard Flashers
LH HEATED
SEATDriver's Heated Seat
Blank Not Used
BCM ACCIgnition Signal: Hot in ACC and Run,
Body Control Module
Blank Not Used
LOW BLOWER Low Blower
ABS Anti-Lock Brakes
TURN
SIGNALS,
CORN LPSTurn Signals, Cornering Lamps
RADIO, HVAC,
RFA,
CLUSTERRadio, Heating Ventilation Air
Conditioning Head, Remote Keyless
Entry, Cluster
HIGH BLOWER High Blower
RH HEATED
SEATPassenger's Heated Seat
STRG WHL
CONTAudio Steering Wheel Controls
WIPER Windshield WipersUnderhood Fuse Block
Some fuses and relays are located in the underhood
fuse block on the passenger's side of the vehicle in the
engine compartment. See
Engine Compartment
Overview on page 5-12or more information on location.
Fuses Usage
1 Anti-Lock Brake System
2 Starter Solenoid
3Power Seats, Rear Window
Defogger Heated Seats
5-91

Fuses Usage
4High Blower, Hazard Flasher,
Stoplamps, Power Mirror, Door
Locks
5Ignition Switch, BTSI, Stoplamps,
Anti-Lock Brake System, Turn
Signals, Cluster, Air Bag, Daytime
Running Lamps Module
6 Cooling Fan
7Retained Accessory Power, Keyless
Entry, Data Link, Heating Ventilation
Air Conditioning Head, Cluster,
Radio, Cigarette Lighter
8Ignition Switch, Wipers, Radio,
Steering Wheel Controls, Body
Control Module, Power Windows,
Sunroof, Heating Ventilation Air
Conditioning Controls, Daytime
Running Lamps, Rear Window
Defogger Relay
Relays Usage
9 Cooling Fan 2
10 Cooling Fan 3
11 Starter Solenoid
12 Cooling Fan 1
13 Ignition Main
14 Air Pump (Optional)
15 Not Used
16 Horn
17 Fog Lamps
18 Not Used
19 Fuel Pump
5-92

E
Electrical System............................................5-88
Add-On Equipment......................................5-88
Fuses and Circuit Breakers...........................5-89
Headlamp Wiring.........................................5-88
Power Windows and Other Power Options......5-88
Windshield Wiper Fuses...............................5-88
Emergency Trunk Release Handle.....................2-14
Emissions Inspection and Maintenance
Programs...................................................3-33
Engine Coolant Level Check.............................6-10
Engine Cooling When Trailer Towing..................4-41
Engine Oil Additives........................................5-16
Engine Oil Level Check...................................6-10
Engine Oil Scheduled Maintenance..................... 6-5
Engine..........................................................5-18
Air Cleaner/Filter.........................................5-18
Battery.......................................................5-42
Change Engine Oil Light...............................3-35
Check and Service Engine Soon Light............3-31
Compartment Overview................................5-12
Coolant Heater............................................2-21
Coolant Temperature Gage...........................3-30
Coolant Temperature Warning Light................3-29
Coolant......................................................5-23
Cooling System Inspection............................6-14Engine (cont.)
Exhaust.....................................................2-30
Oil .............................................................5-13
Overheating................................................5-26
Starting......................................................2-20
Enhanced Traction System (ETS)......................4-10
Warning Light.............................................3-28
Entry Lighting.................................................3-14
Express-Down Window....................................2-16
Extender, Safety Belt.......................................1-29
Exterior Lamps...............................................3-11
F
Filter.............................................................5-18
Engine Air Cleaner......................................5-18
Finding a Station....................................3-40, 3-42
Finish Care....................................................5-83
Finish Damage...............................................5-84
Fixed Mast Antenna........................................3-52
Flash-to-Pass................................................... 3-7
Flat Tire, Changing.........................................5-67
Flat Tire........................................................5-66
Fluid.............................................................5-19
Automatic Transaxle.....................................5-19
Power Steering...........................................5-36
Windshield Washer......................................5-38
5