1999 BUICK CENTURY ignition

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6-15 Engine Oil Additives
Don't add anything to your oil. Your dealer is ready to
advise if you think something should be added.
When to Change Engine Oil
Your vehicle has a computer that lets you know when to
change your engine oil. This is not based on mileage,
but on engine revolutions and engine operating
temperature. When the computer has calculated that the
oil needs changing, the Oil Life Monitor will indicate
that a change is necessary. The mileage between oil
changes will vary depending on how you drive your
vehicle
-- usually between 3,000 miles (5 000 km) and
7,500 miles (12 500 km) since your last oil change.
Under severe conditions, the indicator may come on
before 3,000 miles (5 000 km). Never drive your vehicle
more than 7,500 miles (12 500 km) or 12 months
(whichever occurs first) without an oil change.
The system won't detect dust in the oil. So, if you
drive in a dusty area, be sure to change your oil every
3,000 miles (5 000 km) or sooner. Remember to
reset the CHANGE OIL SOON light whenever the oil
is changed.How to Reset the Oil Life Monitor
After changing the engine oil, the system must be reset.
With the ignition key in RUN but the engine off, fully
push and release the accelerator pedal slowly three times
within five seconds. If the CHANGE OIL SOON light
flashes, the system is resetting. Turn the key to OFF,
then start the vehicle. If the CHANGE OIL SOON
light comes back on, the system has not reset. Repeat
the procedure.
What to Do with Used Oil
Did you know that used engine oil contains certain
elements that may be unhealthy for your skin and could
even cause cancer? Don't let used oil stay on your skin
for very long. Clean your skin and nails with soap and
water, or a good hand cleaner. Wash or properly throw
away clothing or rags containing used engine oil. (See
the manufacturer's warnings about the use and disposal
of oil products.)
Used oil can be a real threat to the environment. If you
change your own oil, be sure to drain all free
-flowing oil
from the filter before disposal. Don't ever dispose of oil
by putting it in the trash, pouring it on the ground, into
sewers, or into streams or bodies of water. Instead,
recycle it by taking it to a place that collects used oil. If
you have a problem properly disposing of your used oil,
ask your dealer, a service station or a local recycling
center for help.

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6-17
Passenger Compartment Air Filter
The passenger compartment
air filter is located
underneath your hood just
below the windshield wiper
arm on the passenger side
(underneath the air inlet
grille) of the vehicle.
The filter traps most of the pollen from the air entering
the air conditioning module. Like your engine's air
cleaner filter, it may need to be changed periodically.
For information on how often to change the passenger
compartment air filter, see ªMaintenance Scheduleº in
the Index.
To change the passenger compartment air filter, use the
following steps:
1. Turn off the ignition when the windshield wipers are
in the up position.2. Raise the hood.
3. Remove (disconnect) the windshield washer pump
hose from the fender rail and air inlet grille.
4. Reposition the hood weatherstrip from the
passenger's side of the vehicle (peel back halfway to
center).
5. Remove (disconnect) the air inlet grille retainers.
6. Remove (disconnect) the air inlet grille.
7. Remove (disconnect) the passenger compartment
air filter.
8. Then install the new air filter. For the type of filter to
use, see ªNormal Maintenance Replacement Partsº
in the Index.
9. Reposition the air inlet grille.
10. Replace the air inlet grille retainers.
11. Reposition the hood weatherstrip.
12. Reconnect the windshield washer pump hose to the
fender rail air inlet grille.
13. Close the hood.
14. Return the windshield wipers to the park position.

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6-39
Windshield Wiper Blade
Replacement
Windshield wiper blades should be inspected at least
twice a year for wear or cracking. See ªWiper Blade
Checkº in Section 7 of this manual under Part B ªOwner
Checks and Servicesº for more information.
1. Turn on the wipers to the low
-wipe setting.
2. Turn off the ignition while the wipers are at the
outer positions of the wiper pattern. The blades are
more accessible for removal/replacement while in
this position.
3. Pull the windshield wiper arm 3 to 4 inches (7.5 to
10 cm) away from the windshield.
4. While holding the wiper arm away from the glass,
push the release clip from under the windshield
wiper arm connecting point and slide the blade
assembly down toward the glass to remove it from
the wiper arm.
5. Slide the new wiper blade securely on the wiper arm
until you hear the release clip ªclickº into place.
For wiper blade replacement length and type, see
ªNormal Maintenance Replacement Partsº in the Index.

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6-42 Low Tire Inflation Monitor System
(If Equipped)
The low tire inflation monitor system can alert you to a
large change in the pressure of one tire. The system
ªlearnsº the pressure at each tire throughout the
operating speed range of your vehicle. The system
normally takes between 45 and 90 minutes of driving to
learn the tire pressures. This time may be longer
depending on your individual driving habits. Learning
need not be accumulated during a single trip. Once
learned, the system will remember the tire pressures
until the system is recalibrated.
After the system has learned tire pressures with properly
inflated tires, the LOW TIRE light will come on if the
pressure in one tire becomes 12 psi (83 kPa) lower than
the other three tires. The low tire inflation monitor
system won't alert you if the pressure in more than one
tire is low, if the system is not properly calibrated, or if
the vehicle is moving faster than 60 mph (95 km/h).
The low tire inflation monitor system detects differences
in tire rotation speeds that are caused by changes in
tire pressure. The system can alert you about a low
tire
-- but it doesn't replace normal tire maintenance.
See ªTiresº in the Index.When the LOW TIRE light comes on, you should stop
as soon as you can and check all your tires for damage.
(If a tire is flat, see ªIf a Tire Goes Flatº in the Index.)
Also check the tire pressure in all four tires as soon as
you can. See ªInflation
- Tire Pressureº in the Index.
The light will come on and stay on until you turn off the
ignition or press the RESET button.
Don't reset the low tire inflation monitor system without
first correcting the cause of the problem and checking
and adjusting the pressure in all four tires. If you reset
the system when the tire pressures are incorrect, the
system will not work properly and may not alert you
when a tire is low.
Any time you adjust a tire's pressure, rotate your tires,
or have one or more tires repaired or replaced, you'll
need to reset (calibrate) the low tire inflation monitor
system. You'll also need to reset the system whenever
you buy new tires and whenever the vehicle's battery
has been disconnected.
To reset (calibrate) the system: turn the ignition switch
to RUN. Then press and hold the RESET button for
about five seconds.

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6-60
Circuit
BreakerDescription
A Tire Inflation Monitor Reset Button
B Power Windows/Sunroof
C Rear Defog
D Power SeatsFuse Description
1 Not Used
4 Ignition Signal
-- Hot in Run and
Start
-- PCM, BCM U/H Relay
5 Remote Radio Premium Sound
6 Power Mirrors
8 Panel Dimming
10 Ignition Signal
-- Hot in Run, Unlock and
Start
-- Cluster, Powertrain Control
Module, Body Control Module
13 DRL Module
14 Interior Lamps
15 Door Locks
17 Taillamps, License Lamp
18 Radio
19 Heated Mirror
20 Cruise Control
22 Clusters
23 Cigarette Lighter
-- Auxiliary Power
Connection (Power Drop), Data Link

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6-61
Fuse Description
24 Stoplamps
26 Parking Lamps
27 Auxiliary Power Connection
(Power Drop)
-- Hot in ACC and Run
28 Crank Signal
-- Body Control Module,
Cluster, Powertrain Control Modules
29 Ignition Signal
-- HVAC Control Head
30 Brake Transmission Shift Interlock (BTSI)
31 Air Bag
32 Body Control Module
33 Hazard Flashers
34 Not UsedFuse Description
36 Ignition Signal
-- Hot in ACC and
Run
-- Body Control Module
38 Low Blower
39 Anti
-Lock Brakes
40 Turn Signals
41 Radio, HVAC Head, Remote Keyless
Entry, Cluster
42 High Blower
43 Not Used
44 Audio Steering Wheel Controls
45 Wipers

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6-62
Underhood Electrical Center -- Passenger's Side
Some fuses and relays are located in the underhood
electrical center on the passenger's side of the
engine compartment.Fuse Description
1 ABS
2 Starter Solenoid
3 Power Seats, Rear Defog
4 High Blower, Hazard Flasher,
Stoplamps, Power Mirror, Door Locks
5 Ignition Switch, BTSI, Stoplamps,
ABS, Turn Signals, Cluster, Air Bag,
DRL Module
6 Cooling Fan
7 Interior Lamps, Retained Accessory
Power, Keyless Entry, Data Link, HVAC
Head, Cluster, Radio, AUX Power
(Power Drop), Cigarette Lighter
8 Ignition Switch, Wipers, Radio, Steering
Wheel Controls, Body Control Module,
AUX Power (Power Drop), Power
Windows, Sunroof, HVAC Controls,
DRL, Rear Defog Relay

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6-63
Relay Description
9 Cooling Fan 2
10 Cooling Fan 3
11 Starter Solenoid
12 Cooling Fan 1
13 Ignition Main
14 Not Used
15 A/C Clutch
16 Horn
17 Not Used
18 Not Used
19 Fuel Pump
20 Not Used
21 Generator
22 ECM
23 A/C Compressor Clutch
24 Cooling Fan
25 Electronic Ignition
26 TransaxleFuse Description
27 Horn
28 Fuel Injector
29 Oxygen Sensor
30 Engine Emissions
31 Not Used
32 Headlamp (Right)
33 Rear Compartment Release
34 Parking Lamps
35 Fuel Pump
36 Headlamp (Left)
37 Spare
38 Spare
39 Spare
40 Spare
41 Spare
42 Spare
43 Fuse Puller
SYMBOL A/C Compressor Clutch Diode