brakes BUICK LUCERNE 2007 Owner's Manual

Automatic Transaxle Operation
Your vehicle may have a shift lever located either
on the steering column or on the console between
the seats.
PARK (P):This position locks your front wheels.
It is the best position to use when you start your
engine because your vehicle cannot move easily.
{CAUTION:
It is dangerous to get out of your vehicle
if the shift lever is not fully in PARK (P)
with the parking brake rmly set. Your
vehicle can roll.
CAUTION: (Continued)
CAUTION: (Continued)
Do not leave your vehicle when the engine
is running unless you have to. If you have
left the engine running, the vehicle can
move suddenly. You or others could be
injured. To be sure your vehicle will not
move, even when you are on fairly level
ground, always set your parking brake
and move the shift lever to PARK (P). See
Shifting Into Park (P) on page 123.Ifyou
are pulling a trailer, seeTowing a Trailer on
page 315.
Make sure the shift lever is fully in PARK (P) before
starting the engine. Your vehicle has an automatic
transaxle shift lock control system. You have to fully
apply your regular brakes before you can shift from
PARK (P) while the ignition is in RUN. If you cannot
shift out of PARK (P), ease pressure on the shift
lever and push the shift lever all the way into
PARK (P) as you maintain brake application.
Then move the shift lever into the gear you want.
SeeShifting Out of Park (P) on page 125.
119

DRIVE (D):This position is for normal driving. It
provides the best fuel economy for your vehicle. If
you need more power for passing, and you are:
Going less than about 35 mph (55 km/h), push
your accelerator pedal about halfway down.
Going about 35 mph (55 km/h) or more, push
the accelerator all the way down.
You will shift down to the next gear and have
more power.
Downshifting the transaxle in slippery road
conditions could result in skidding, see “Skidding”
underLoss of Control on page 290.
THIRD (3):This position is also used for normal
driving. It reduces vehicle speed more than
DRIVE (D) without using your brakes. You might
choose THIRD (3) instead of DRIVE (D) when
driving on hilly, winding roads, when towing
a trailer, so there is less shifting between gears
and when going down a steep hill.
SECOND (2):This position reduces vehicle speed
even more than THIRD (3) without using your
brakes. You can use SECOND (2) on hills. It can
help control your speed as you go down steep
mountain roads, but then you would also want to
use your brakes off and on.Notice:Driving in SECOND (2) for more than
25 miles (40 km) or at speeds over 55 mph
(90 km/h) may damage the transaxle. Also,
shifting into SECOND (2) at speeds above
65 mph (105 km/h) can cause damage. Drive in
THIRD (3) or DRIVE (D) instead of SECOND (2).
FIRST (1):This position reduces vehicle speed
even more than SECOND (2) without using your
brakes. You can use it on very steep hills, or in
deep snow or mud. If the shift lever is put in
FIRST (1) while going forward, the transaxle will
not shift into rst gear until the vehicle is going
slowly enough.
Notice:Spinning the tires or holding the
vehicle in one place on a hill using only the
accelerator pedal may damage the transaxle.
If you are stuck, do not spin the tires. When
stopping on a hill, use the brakes, or parking
brake to hold the vehicle in place.
121

Torque Lock
If you are parking on a hill and you do not shift your
transaxle into PARK (P) properly, the weight of the
vehicle may put too much force on the parking pawl
in the transaxle. You may nd it difficult to pull the
shift lever out of PARK (P). This is called torque
lock. To prevent torque lock, set the parking brake
and then shift into PARK (P) properly before you
leave the driver’s seat. To nd out how, seeShifting
Into Park (P) on page 123.
If torque lock does occur, you may need to
have another vehicle push yours a little uphill to
take some of the pressure from the parking pawl in
the transaxle, so you can pull the shift lever out
of PARK (P).
Shifting Out of Park (P)
Your vehicle has an automatic transaxle shift lock
control system. You have to fully apply your regular
brakes before you can shift from PARK (P) when
the ignition is RUN. SeeAutomatic Transaxle
Operation on page 119.
The shift lock control system is designed to do the
following:
Prevent the ignition key from being removed
unless the shift lever is in PARK (P).
Prevent movement of the console shift lever
out of PARK (P) unless the ignition is in a
position other than OFF.
The shift lock control system is always functional
except in the case of a dead battery or low
voltage (less than 9 V) battery.
If you cannot shift out of PARK (P), ease the
pressure on the shift lever. Push the shift lever
all the way into PARK (P) as you maintain
brake application. Then move the shift lever into
the gear you want.
If you are still having a problem shifting, then have
your vehicle serviced soon.
125

When the System Does Not Seem to
Work Properly
If the URPA system will not activate due to a
temporary condition, the message PARK ASSIST
OFF will be displayed on the DIC and a red light will
be shown on the rear URPA display when the shift
lever is moved into REVERSE (R). This occurs
under the following conditions:
The driver disables the system. SeeDIC
Controls and Displays on page 212.
The parking brake pedal is pressed.
A trailer was attached to your vehicle, or a
bicycle or an object was hanging out of your
trunk during your last drive when you turned off
the vehicle. If the attached objects are removed
from your vehicle before the start of your next
drive, the system will return to normal operation
unless an object is detected when the vehicle is
shifted into REVERSE (R). If this occurs, URPA
assumes the object is still attached, so you will
have to wait until the vehicle is driven forward
above 15 mph (25 km/h) before URPA will
return to normal operation.
The ultrasonic sensors are not kept clean. So,
be sure to keep your vehicle’s rear bumper free
of mud, dirt, snow, ice, and slush. For cleaning
instructions, seeWashing Your Vehicle on
page 422. If the DIC still displays the PARK
ASSIST OFF message after cleaning the
bumper and driving forward at a speed of at
least 15 mph (25 km/h), see your dealer.
Other conditions that may affect system
performance include vibrations from a
jackhammer or the compression of air brakes
on a very large truck or other mechanical
devices that interfere with URPA performance.
When URPA is disabled without driver action
and the driver attempts to turn URPA back on
using the Driver Information Center (DIC), the
PARK ASSIST ON option will not be selectable
if the necessary conditions stated above for
normal system operation are not met.
As always, drivers should use care when backing
up a vehicle. Always look behind you, being sure to
check for other vehicles, obstructions and blind
spots.
180

Anti-Lock Brake System
Warning Light
With the anti-lock brake
system, the light(s) will
come on when your
engine is started and
may stay on for
several seconds.
That’s normal.
If the light stays on, turn the ignition to OFF. Or, if
the light comes on when you’re driving, stop as
soon as possible and turn the ignition off. Then start
the engine again to reset the system. If the light still
stays on, or comes on again while you’re driving,
your vehicle needs service. If the regular brake
system warning light isn’t on, you still have brakes,
but you don’t have anti-lock brakes. If the regular
brake system warning light is also on, you don’t
have anti-lock brakes and there’s a problem with
your regular brakes. SeeBrake System Warning
Light on page 201.
The anti-lock brake system warning light will come
on briey when you turn the ignition key to RUN.This is normal. If the light doesn’t come on then,
have it xed so it will be ready to warn you if there
is a problem.Traction Control System (TCS)
Warning Light
This warning light
should come on briey
when the engine is
started.
If the warning light does not come on then, have it
xed so it will be ready to warn you if there is a
problem. If it stays on, or comes on when you are
driving a SERVICE TRACTION CONTROL
message will appear in the Driver Information
Center (DIC). This indicates that there may be a
problem with your traction control system and your
vehicle may need service. When this warning light
is on and the SERVICE TRACTION CONTROL
message appears on the DIC, the system will not
limit wheel spin. Adjust your driving accordingly.
202

SERVICE BRAKE ASSIST
This message displays if there is a problem with the
brake system. The brake system warning light and
the anti-lock brake system warning light may also
be displayed on the instrument panel cluster. See
Brake System Warning Light on page 201and
Anti-Lock Brake System Warning Light on page 202
for more information. If this happens, stop as soon
as possible and turn off the vehicle. Restart the
vehicle and check for the message on the DIC
display. If the message is displayed or appears
again when you begin driving, the brake system
needs service. See your dealer as soon as
possible. SeeBrakes on page 367for more
information.
SERVICE BRAKE SYSTEM
This message displays if the ignition is on to
inform the driver that the brake uid level is low.
Have the brake system serviced by your dealer as
soon as possible. The brake system warning
light also appears on the instrument panel cluster
when this message appears on the DIC. See
Brake System Warning Light on page 201.
SERVICE PARK ASSIST
If your vehicle has this feature, this message
displays if there is a problem with the Ultrasonic
Rear Parking Assist (URPA) system. Do not
use this system to help you park. SeeUltrasonic
Rear Parking Assist (URPA) on page 178for more
information. See your dealer for service.
SERVICE POWER STEERING
Your vehicle may have a speed variable assist
steering system. SeeSteering on page 285.
This message displays if a problem is detected with
the speed variable assist steering system. When
this message is displayed, you may notice that the
effort required to steer the vehicle decreases or
feels lighter, but you will still be able to steer the
vehicle.
227

Control of a Vehicle
You have three systems that make your
vehicle go where you want it to go. They are the
brakes, the steering, and the accelerator. All
three systems have to do their work at the places
where the tires meet the road.
Sometimes, as when you are driving on snow or
ice, it is easy to ask more of those control systems
than the tires and road can provide. That means
you can lose control of your vehicle. SeeTraction
Control System (TCS) on page 283.
Adding non-GM accessories can affect your
vehicle’s performance. SeeAccessories and
Modications on page 325.
Braking
SeeBrake System Warning Light on page 201.
Braking action involves perception time and
reaction time.
First, you have to decide to push on the brake
pedal. That is perception time. Then you have to
bring up your foot and do it. That is reaction time.
Average reaction time is about three-fourths of a
second. But that is only an average. It might be less
with one driver and as long as two or three seconds
or more with another. Age, physical condition,
alertness, coordination, and eyesight all play a part.
So do alcohol, drugs, and frustration. But even in
three-fourths of a second, a vehicle moving at
60 mph (100 km/h) travels 66 feet (20 m). That
could be a lot of distance in an emergency, so
keeping enough space between your vehicle and
others is important.
And, of course, actual stopping distances vary
greatly with the surface of the road, whether it is
pavement or gravel; the condition of the road,
whether it is wet, dry, or icy; tire tread; the
condition of the brakes; the weight of the vehicle;
and the amount of brake force applied.
280

Avoid needless heavy braking. Some people drive
in spurts — heavy acceleration followed by
heavy braking — rather than keeping pace with
traffic. This is a mistake. The brakes may not have
time to cool between hard stops. The brakes
will wear out much faster if you do a lot of heavy
braking. If you keep pace with the traffic and
allow realistic following distances, you will
eliminate a lot of unnecessary braking. That means
better braking and longer brake life.
If your vehicle’s engine ever stops while you are
driving, brake normally but do not pump the
brakes. If you do, the pedal may get harder to
push down. If the engine stops, you will still have
some power brake assist. But you will use it
when you brake. Once the power assist is used
up, it may take longer to stop and the brake pedal
will be harder to push.
Adding non-GM accessories can affect your
vehicle’s performance. SeeAccessories and
Modications on page 325.Anti-Lock Brake System (ABS)
Your vehicle has the Anti-Lock Brake System
(ABS), an advanced electronic braking system
that will help prevent a braking skid.
When you start your engine and begin to drive
away, ABS will check itself. You may hear a
momentary motor or clicking noise while this test
is going on, and you may even notice that
your brake pedal moves a little. This is normal.
If there is a problem
with ABS, this warning
light will stay on.
SeeAnti-Lock Brake
System Warning
Light on page 202.
281

Let us say the road is wet and you are driving
safely. Suddenly, an animal jumps out in front of
you. You slam on the brakes and continue braking.
Here is what happens with ABS:
A computer senses that wheels are slowing down.
If one of the wheels is about to stop rolling, the
computer will separately work the brakes at each
front wheel and at both rear wheels.ABS can change the brake pressure faster than
any driver could. The computer is programmed
to make the most of available tire and road
conditions. This can help you steer around the
obstacle while braking hard.
As you brake, your computer keeps receiving
updates on wheel speed and controls braking
pressure accordingly.
282

Remember: ABS does not change the time you
need to get your foot up to the brake pedal or
always decrease stopping distance. If you get too
close to the vehicle in front of you, you will not have
time to apply your brakes if that vehicle suddenly
slows or stops. Always leave enough room up
ahead to stop, even though you have ABS.
Using ABS
Do not pump the brakes. Just hold the brake pedal
down rmly and let anti-lock work for you. You may
hear the anti-lock pump or motor operate, and feel
the brake pedal pulsate, but this is normal.
Braking in Emergencies
With ABS, you can steer and brake at the same
time. In many emergencies, steering can help you
more than even the very best braking.
Traction Control System (TCS)
Your vehicle has a traction control system that limits
wheel spin. This is especially useful in slippery road
conditions. The system operates only if it senses
that the front wheels are spinning too much or
beginning to lose traction. When this happens, the
system works the front brakes and reduces engine
power (by closing the throttle and managing engine
spark) to limit wheel spin.
The traction control system and StabiliTrak
®
warning light will ash when the traction control
system is limiting wheel spin. SeeTraction Control
System (TCS) Warning Light on page 202for
more information. You may feel or hear the system
working, but this is normal.
If your vehicle is in cruise control when the
traction control system begins to limit wheel spin,
the cruise control will automatically disengage.
When road conditions allow you to safely use
it again, you may re-engage the cruise control.
SeeCruise Control on page 167for more
information.
283