2005 PORSCHE BOXSTER brake

52
Controls, Instruments The parking brake warning lights will go out after
the parking brake is fully released.
The warning lights are not an indicator that the
parking brake is fully set; it is only intended to be
a warning to release the parking brake before dri-
ving the car. Caution!
A partially engaged brake will overheat the
rear brakes, reduce their effectiveness and
cause excessive wear.
fRelease the parking brake fully.
fWhen parking your car, always set the parking
brake by pulling all the way up on the lever.
fMove the selector lever to “P” (Tiptronic) or
move the gearshift lever to reverse or first
gear (Manual transmission).
fOn hills also turn the front wheels towards the
curb.
Brakes fMake it a habit to check the operation of your
brakes before driving.
Keep in mind that the braking distance increases
very rapidly as the speed increases. At 60 mph or
100 km/h, for example, it is not twice but four ti-
mes longer than 30 mph or 50 km/h. Tire traction
is also less effective when the roads are wet or
slippery.
fTherefore, always maintain a safe distance
from the car in front of you.
Vehicles without Porsche Ceramic
Composite Brake (PCCB)
Even though the brake discs consist of alloyed
grey cast iron, they will unavoidably start to corro-
de if your car is parked for an extended period.
The brakes will tend to “rub” as a result.
The nature, extent and effects of corrosion de-
pend on the amount of time the vehicle was par-
ked, whether granular or liquid road salt was
spread and whether grease-dissolving agents
were used in car washes.
If the braking comfort is noticeably impaired, we
recommend having the brake system checked by
experts at an authorized Porsche dealer.
Brake system function Your Porsche is equipped with a power assisted
hydraulic dual circuit brake system with disc bra-
kes at the front and rear.
Both circuits function independently. One brake
circuit operates the front and the other operates
the rear.
If one brake circuit has failed, the other will still
operate. However, you will notice an increased pe-
dal travel when you apply the brakes.
Failure of one brake circuit will cause the stopping
distance to increase.
Warning!
Risk of an accident.
In the unlikely event of hydraulic failure of
one brake circuit:
fPush the brake pedal down firmly and hold it in
that position.
A mechanical linkage activates the second cir-
cuit, and you will be able to bring the vehicle to
a stop.
fAfter bringing your vehicle to a complete stop,
avoid driving the vehicle and instead have it to-
wed to the nearest authorized Porsche dealer for repair.
Parking brake warning light USA
Parking brake warning light
Canada

Controls, Instruments
53
If the warning lights in the instrument panel and on-
board computer go on while driving, the brake flu-
id level may be too low, or (if the brake pedal travel
has increased) one of the two brake circuits may
have failed.
A greater braking pressure will be required, stop-
ping distances will be longer and the braking beha-
vior will change, particularly in curves.
With correctly adjusted brakes, and a correctly
working brake system, the pedal travel to the
point of brake actuation should be 1-3/16" to
1-9/16" or 30 to 40 mm.
Whenever the brake pedal travel exceeds this dis-
tance, have the brake system checked.
Brake pedal
Warning!
Risk of an accident.
Any obstruction of the pedal could increase
the stopping distance.
fAlways check the movement of the brake pedal
before driving and make sure that it is not obs-
tructed by a floor mat or any other object.
fSecure the floor mat to prevent it from sliding
into positions that could interfere with the safe
operation of your vehicle.
Your Porsche dealer will be glad to offer you
floor mats of the correct size including a secu-ring possibility.
Note
In case one of the two brake circuits fails, increa-
sed pedal travel is required to bring your vehicle
to a full stop.
Warning!
To avoid overheating and premature wear of
the brakes:
fBefore descending a steep grade, reduce
speed and shift the transmission into a lower
gear or driving position to control speed.
fDo not ride the “brakes” by resting your foot on
the pedal when not intending to apply brake
pressure.
fDo not hold the pedal down too long or too of-
ten.
This could cause the brakes to get hot and not function properly.
Brake warning light USA
Brake warning light
Canada

54
Controls, Instruments
Brake booster The brake booster assists braking only when
the engine is running.
When the car is moving while the engine is not run-
ning, or if the brake booster is defective, more
pressure on the brake pedal is required to bring
the car to a stop.
Moisture or road salt on brakes affects braking.
When the vehicle is driven on salted roads for ex-
tended periods, the brakes should be washed
down thoroughly about every 2 weeks. An auto-
matic carwash facility cannot do this job properly.
Brakes will dry after a few cautious brake applica-
tions.
Warning!
Driving through water may reduce traction.
Moisture on brakes from road water, car
wash, or coating of road salt may affect bra-
king efficiency.
fCautiously apply brakes to test brakes after being exposed.
Brake wear Your car has excellent brakes, but they are still
subject to wear. The rate at which they wear de-
pends on how the brakes are used.
fHave the brake system inspected at the inter-
vals recommended in your Maintenance Book-
let.
If the lights in the instrument panel and on-board
computer stay on when the engine is running or
come on while driving, the brake pads are worn,
excessively.
fDo not continue to operate the vehicle.
Have your authorized Porsche dealer inspect
or replace the brake pads.
Brake pads Wear on the brake pads and brake discs depends
to a great extent on the driving style and the con-
ditions of use and therefore cannot be expressed
in actual miles on the road.
The high-performance brake system is designed
for optimal braking effect at all speeds and tempe-
ratures.
Certain speeds, braking forces and ambient
conditions (such as temperature and humidity)
therefore might cause the brakes to squeal.
New brake pads or linings
New brake pads have to be “broken in”, and there-
fore only attain optimal friction when the car has
covered several hundred miles or km.
The slightly reduced braking ability must be com-
pensated for by pressing the brake pedal harder.
This also applies whenever the brake pads and
brake discs are replaced.
Warning light USA
Warning light Canada

Controls, Instruments
55
ABS Brake System
(Antilock Brake System) The ABS system represents a major contribution
to the enhancement of active safety in your vehic-
le. This system prevents the wheels from locking
in a panic stop on almost all road surfaces. With the ABS system in your vehicle, the fol-
lowing areas are enhanced:
Steering, vehicle remains steerable under all bra-
king forces when ABS is engaged.
Good directional control, no swerving caused
by locking of wheels under braking conditions.
Shorter stopping distance, stopping distances
are usually reduced because controlled braking is
maximized.
Prevention of wheel lock up, no brake- induced
sliding and thus no localized tire wear from emer-
gency braking.
The crucial advantage of the ABS system over a
conventional brake system is in the area of
maintaining directional control and maneuverabili-
ty of the car in emergency situations during nor-
mal driving, including panic braking in turns.
Warning!
The increased control that is provided should
not induce you to take greater risks with your
safety. The limits dictated by the laws of phy-
sics cannot be overcome, even with ABS.
The risk of accidents due to inappropriate
speed cannot be reduced, even by the ABS.
The driver bears the responsibility for all dri-
ving maneuvers.
fAdapt your driving style to the prevailing road
and weather conditions.
fObey all traffic laws.
Other vehicles not equipped with the ABS
system may not be able to maintain control,
especially on wet or poor road surfaces and
thus may be more likely to impact you from
behind.
fTo minimize that risk, use your ABS system to
increase your ability to maneuver to avoid dan-
gerous situations and not merely to try to stop in the shortest distance possible.

56
Controls, Instruments
Operation of the ABS system A wheel speed sensor is mounted to each of the
four wheels. If wheel lock-up of either of the front
wheels or the rear wheels is sensed during bra-
king, the brake pressure is adjusted automatically
until the wheel no longer slips. The brake pressure
is regulated for each front wheel individually and
for both of the rear wheels together.
On a road surface which is slippery on only one si-
de, the rear wheel which is braking on the slippery
surface determines the brake pressure which will
be applied equally to both rear wheels. This ensu-
res that directional stability is maintained. Howe-
ver, if braking forces approach the wheel lock-up
point for all wheels (panic braking) the ABS system
will intervene to provide a rapid rythmic braking.
The proper operation of ABS is perceived by the
driver as a pulsating brake pedal in conjunction
with audible noise and perhaps some vibration.
fIf you experience these sensations while dri-
ving or a road surface with questionable trac-
tion, reduce vehicle speed appropriate for the
prevailing road conditions.
The functional readiness of all the main electrical
components of the ABS is checked by an electro-
nic monitoring system both before and while you
drive. When the ignition is switched on the ABS warning
light will light up while the system is electronically
interrogated and goes out when the engine is star-
ted if the check is not yet complete.
If the ABS warning lamp fails to go out, this indica-
tes that ABS has been deactivated due to a fault.
If the warning lights in the instrument panel and on-
board computer light up while you are driving, this
indicates that a fault has occurred. In both cases,
normal braking, as in vehicles without ABS, is still
retained.
The ABS system should, however, be examined at
an authorized Porsche dealer immediately to pre-
vent the occurrence of further faults.
fIf the ABS system becomes inoperative, take
your vehicle to your authorized Porsche dealer
immediately.
Warning!
The control unit of the ABS brake system is
set for standard tire size. If non-standard ti-
res are installed, the control unit may misin-
terpret the speed of the vehicle, because of
the variant data it receives from the sensors
on the axles.
fUse only tire makes and types tested by Porsche.
Warning light USA
Warning light Canada

58
Controls, Instruments
Porsche Stability Management
(PSM)PSM is an active control system for stabilisation of
the vehicle during extreme driving manoeuvres.
Warning!
The increased control that is provided should
not induce you to take greater risks with your
safety. The limits dictated by the laws of phy-
sics cannot be overcome, even with PSM.
The risk of accidents due to inappropriate
speed cannot be reduced, even by PSM.
The driver bears the responsibility for all dri-
ving maneuvers.
fAdapt your driving style to the prevailing road
and weather conditions.
fObey all traffic laws. Advantages of PSM – Superior traction and lane-holding ability in all
driving situations – even on road surfaces with
varying friction.
– PSM actively stabilizes the vehicle during dyna-
mic driving maneuvres (e.g. rapid steering mo-
vements, during lane changes or on alterna-
ting curves).
– Improved braking stability in curves and on dif-
ferent or varying road surfaces.
Readiness for operationPSM is switched on automatically every time you
start the engine. FunctionSensors at the wheels, brakes, steering system
and engine continuously measure:
– Speed
– Direction of travel (steering angle)
– Lateral acceleration
– Rate of turn about the vertical axis
PSM uses these values to determine the direction
of travel desired by the driver.
PSM intervenes and corrects the course if the
actual direction of motion deviates from the
desired course (steering-wheel position):
It brakes individual wheels as needed. In addition,
the engine power may be manipulated in order to
stabilise the vehicle. The events below inform the driver of PSM control
operations and warn him to adapt his driving style
to the road conditions:
– The multi-functional information light on the
instrument panel flashes.
– Hydraulic noises can be heard.
– The vehicle decelerates and steering-wheel
forces are altered as the PSM controls the
brakes.
– Reduced engine power.
– The brake pedal pulsates and its position is
changed during braking.
However, it is possible at any time to achieve
full vehicle deceleration by increasing the foot
pressure slightly.

Controls, Instruments
59
Examples of PSM control operations
– If the “front wheels of the vehicle drift” on a
bend, the rear wheel on the inside of the bend
is braked and the engine power is reduced if
necessary.
– If the rear of the vehicle swings out on a bend,
the front wheel on the outside of the bend is
braked.
PSM should always be switched on during
“normal” driving.
However, it may be advantageous to switch off
PSM temporarily in exceptional situations, for
example:
– On a loose surface or in deep snow,
– When “rocking the vehicle free”, or
– When using snow chains.
Tiptronic vehicles
When the PSM is switched off the slip monitoring
function of the Tiptronic is also deactivated.
Switching off PSMfPress the PSM OFF button.
PSM is switched off after a short delay.
The light-emitting diode in the button is illumi-
nated.
When the PSM is switched off, the multifunc-
tional PSM light on the instrument panel is lit
and a message is shown by the on-board
computer.
A gong also sounds.The following functions stabilise the vehicle in
emergency situations, even with PSM switched
off:
– When PSM is off, the vehicle is stabilised as
soon as one of the two front wheels enters the
ABS control range.
– When PSM is off and Sport mode is on, the
vehicle is stabilised as soon as both front
wheels enter the ABS control range.
One-sided spinning of the wheels is prevented,
even with PSM switched off.
Switching PSM back onfPress PSM OFF button.
PSM is switched on after a short delay.
The light-emitting diode in the button and the
multifunctional PSM light go out.
The on-board computer shows a message.

60
Controls, Instruments
Sport modeA sportier car set-up is obtained when Sport mode
is switched on.
PSM interventions are later than in Normal mode;
the vehicle can be manoeuvred with greater agility
at its performance limits, without the need to
dispense with the assistance of PSM in
emergency situations. This helps to achieve
optimal lap times, particularly on race circuits and
a dry road surface.
– The multifunctional light on the instrument
panel lights up for a lamp check when the
ignition is switched on.
– The light indicates a control operation by
flashing, including when PSM is switched off
(brake control in the event of one-sided wheel
spin).
– In conjunction with a message on the on-board
computer, the light indicates that PSM is
switched off.
A gong also sounds.– Faults are displayed by the light in conjunction
with a message on the on-board computer.
PSM is out of order.
fPlease go to a qualified specialist workshop.
We recommend a Porsche partner for this
work as they have trained workshop personnel
and the necessary parts and tools.
fPlease observe the chapter “STORING YOUR
PORSCHE” on Page 200.
TowingfPlease observe the chapter “TOWING” on Page
254.Checks on test standsWhen carrying out brake tests on roller test
stands a maximum testing speed of 5 mph
(8 km/h) must not be exceeded.
Handbrake checks on the roller brake tester
must be performed only with the ignition switched
off.
Multifunctional PSM light