2004 PORSCHE CAYENNE brakes

Driving and Driving Safety
171
Selector lever positionIndicator for selector lever position and
engaged gearWhen the engine is running, the selector lever
position and engaged gear are indicated.
Selector Lever PositionsP – Parking lockIn selector lever position P, the driven wheels are
mechanically locked.
fEngage parking lock only when vehicle is
stationary.
fEngage parking lock after applying the
parking brake and release it before releasing
the parking brake.
fAlways apply the parking brake before leaving
the vehicle.
The ignition key can be withdrawn only in selector
lever position P.R – ReversefSelect reverse only if car is stationary and the
brake is applied.N – NeutralSelector lever position N must be selected for
towing or in car washes, for example.
fSelect the desired position for moving off
(D, M or R) only when the engine is idling and
when depressing the brake pedal.
D - Automatic selection mode (in the road
driving program)fUse selector lever position D for “normal”
driving.
The gears are shifted automatically according
to the accelerator position and speed.
Depending on the way the vehicle is driven and on
the resistance (e.g. uphill), the gear-changing
points are shifted towards higher or lower engine-
speed ranges. Movement of the accelerator,
driving speed, longitudinal and lateral acceleration
and the road profile all have an influence on the
gear-changing characteristic.
When PSM is switched off, transmission gear
changes are done at higher engine speeds.
Unwanted upward shifts, e.g. before corners, are
prevented by swiftly releasing the accelerator
pedal.
Depending on lateral acceleration, upward
changes on corners are not made until the engine-
speed limit is reached.
During braking, and depending on the amount of
deceleration, the Tiptronic changes down earlier.
For subsequent cornering, the right gear is
engaged when pressure is applied to the brakes
before the corner.
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Driving and Driving Safety
183
Porsche Stability Management (PSM)PSM is an active control system for stabilization of
the vehicle during extreme driving maneuvers. It
operates together with the Porsche Traction
Management (PTM) system.
PSM makes use of both the ABD and TCS
systems, as well as the known functions of the
anti-lock brake system (ABS) and engine drag
torque control system (MSR).
Warning!
In spite of the advantages of PSM, it is still the
driver’s responsibility to adapt her/his driving style
and maneuvers in line with road and weather
conditions, as well as the traffic situation.
The increased safety that is provided should not
induce you to take greater risks with your safety.
The limits set by the physics of driving cannot be
overcome, even with PSM.
Risks of accident due to inappropriate speed
cannot be reduced by PSM.Advantages of PSM
– Best possible traction and lane-holding ability
in all driving situations – even on road surfaces
with varying friction.
– The system compensates for undesired vehi-
cle reactions (load-alteration effect) when the
driver releases the accelerator pedal or brakes
on bends. This compensation functions up to
the maximum lateral acceleration.
– PSM actively stabilizes the vehicle as required
during dynamic driving maneuvers (e.g. rapid
steering movements, during lane changes or
on alternating bends).
– Improved braking stability on corners and on
different or varying road surfaces.
– Improved brake functioning and reduced
stopping distance in the event of emergency
braking.Readiness for operation
PSM is switched on automatically every time you
start the engine.
Function
Sensors at the wheels, brakes, steering system
and engine continuously measure:
– Driving speed
– Direction of travel (steering angle)
– Lateral acceleration
– Longitudinal 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. If neces-
sary, PSM additionally influences the engine power
or the gear-changing characteristic of the
Tiptronic in order to stabilize the vehicle.
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184
Driving and Driving Safety The events below inform the driver of PSM control
operations and warn him to adapt her/his driving
style to the road conditions:
– The multi-functional information light in the
instrument panel lights up.
– Light in the PSM Off button 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.
In order to achieve full vehicle deceleration,
foot pressure must be increased after begin-
ning of the brake pedal pulsing.
Examples of PSM control operations
– If the front wheels of the vehicle drift on a
corner, engine power is reduced and the rear
wheel on the inside of the corner is braked if
necessary.
– If the rear of the vehicle swings out on a
corner, the front wheel on the outside of the
corner is braked.– Brake system prefilling:
The brake system is prepared for possible sub-
sequent emergency braking if the accelerator
pedal is released suddenly and quickly.
The brake system is prefilled and the brake
pads are already applied gently to the brake
discs.
– Brake booster:
In the event of an emergency braking operation
where the pedal force is insufficient, a brake
booster provides the braking pressure neces-
sary for maximum deceleration at all 4 wheels.
Combined use of PSM and PTM/PTM Plus
In order to ensure optimal stabilization of the ve-
hicle, the center differential lock (PTM) and possib-
ly the rear differential lock (PTM Plus) are also
opened when PSM interventions occur.
Tip on driving
When PSM is switched off, wheel-specific brake in-
terventions and the traction control system (TCS)
are also inactive.
The automatic brake differential (ABD) remains on.Off-road PSM
(PSM in Low Range program)
When Low Range is active, an off-road PSM
specially matched to off-road driving is activated
to enhance traction.
In order to improve driveability on difficult terrain,
the response of the off-road PSM is less sensitive
in the low speed range when the vehicle is opera-
ted in the Low Range off-road driving program.
If the brakes are highly stressed, the automatic
brake differential (ABD) switches itself off to
protect the brakes. It remains deactivated until the
brake system has cooled sufficiently.
Engine drag torque control
In conditions of excessive slip, the engine drag
torque control system prevents all driven wheels
from locking up when the car is passing. This is
also the case for downshifts on a slippery road.
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Driving and Driving Safety
189
Engine Braking Support
(Assistance when heading downhill)The Porsche Down-Hill Assistant is an assistance
system which helps the driver at slower downhill
driving up to approx. 12 mph (20 km/h), e.g., on
steep slopes or on wintry mountain roads.
As long as the gas pedal is not used when
traveling downhill, the Porsche Down-Hill Assistant
is active and brakes the vehicle.
If road grip is lost on one or more wheels, the
system brakes the wheels which have good road
contact.
The braking ability of the Engine Braking Support
is affected by slippery surfaces (e.g., on icy or
loose surfaces), like all brakes.
Warning!
Risk of accident, resulting in serious perso-
nal injury or death. Reduced braking ability
on a slippery surface.
fAlways adjust your driving style to the driving situation.
Conditions:
– The gas pedal must not be used when
travelling downhill.
– The speed must not exceed 12 mph
(20 km/h).–Vehicles with Tiptronic S:
The Tiptronic selector lever position D, M or R
must be engaged.
–Vehicles with manual transmission:
The reverse gear or any other gear (1. - 6. )
must be engaged. The clutch pedal must not
be used when travelling downhill.
Tip on driving
The Porsche Down-Hill Assistant is active when
driving downhill either forwards or backwards.
Checks on test standsBrake tests
Brake tests must be carried out only in High Range
and on plate-type test stands or roller test stands.
The following limit values must not be exceeded
on roller test stands:
– Testing speed 4.7 mph (7.5 km/h)
– Test duration 20 seconds
Parking brake test
Parking brake tests on the brake tester must be
performed only with the ignition switched off and
the Tiptronic selector lever in position N or the
gearshift lever in neutral.Balancing wheels on the vehicle
During finish balancing of the wheels, the entire
vehicle must be lifted and the wheels must be free
to turn.
Dynamometer testing procedure Some U.S. states and Canadian provinces con-
duct emissions inspection/maintenance testing
involving the use of two-wheel dynamometer.
A two-wheeled dynamometer is a treadmill type
device upon which a single axle of the car, the dri-
ving axle of the vehicle, rotates to simulate vehicle
operation on the road while the vehicle remains
stationary.
Your Porsche Cayenne has a full-time four-wheel
drive system which cannot be disabled. Severe
d a m a g e t o t h e p o w e r t r a i n c a n re s u l t i f t e s t e d o n a
two-wheel dynamometer.
Warning!
To avoid severe powertrain damage and a
possible unexpected movement of the vehic-
le.
fYour Porsche Cayenne vehicle must never be
tested on a two-wheel dynamometer.
fAdvise the emission station of this warning before testing the vehicle.
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Driving and Driving Safety
195
Off-Road DrivingPlease read this chapter carefully before driving
off road with your Porsche.
The information provided will familiarise you with
the special advantages of your vehicle, allowing
you to arrive at your destination safely every time.
We recommend practicing on less rugged terrain.Vehicles with SportDesign package
Caution!
Risk of damage. On vehicles with Sport-
Design package, front, rear, and side
member trim are painted. Off-road driving
can seriously damage these trim parts.
fWhen driving off-road, make sure these parts
are not damaged.
fMake sure there is sufficient clearance
between obstacles and the underside of the
vehicle.
fAvoid driving through water.
fDo not use side member trims or rear wheel spoilers as a running board.Maintenance Note
Please bear in mind that off-road driving subjects
all vehicle components to considerably more wear
than normal use, making professional inspection
and maintenance after each use a vital precondi-
tion for functioning and safety.
Grains of sand, dirt particles and other abrasive
materials entering the brakes can cause exces-
sive wear or unpredictable braking action.
Rules for off-road drivingfEnsure vehicle is equipped with approved all-
terrain tires.
fPay attention to the ground clearance of the
vehicle.
Please see the chapter “GROUND
CLEARANCE” on Page 357.
fActivate Low Range.
Please see the chapter “SELECTING OFF-
ROAD DRIVING PROGRAM” on Page 178.
fStow or fasten luggage and loads securely.
Please see the chapter “LOADING
INFORMATION” on Page 231.
fIf unknown terrain is obscured from view,
examine it on foot first and traverse it with
extreme caution.
This way, obstacles are easier to recognize
and damage to the vehicle is avoided.fAlways drive with the engine running.
Power steering assistance is provided only
with the engine running.
fDrive slowly and uniformly.
fAlways make sure that the wheels touch the
ground.
fBefore driving through water, check the water
depth, the condition of the surface beneath it
and the speed of the water.
fLook out for obstacles such as boulders,
holes, tree stumps or ruts.
fAlways keep the sliding/lifting roof or
Panorama roof system and the side windows
closed while driving.
fDo not depart from marked routes or paths.
fRespect Nature.
Always obey off-limits signs.
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200
Driving and Driving Safety Soiling can impair the braking action.
fCheck and clean the brakes if they have been
soiled.
Danger of steering assistance failing during
a long journey in the water if the drive belt
slips.
fIf the steering assistance fails, more effort will
be required to steer.
Danger of damaging electrical systems
fAvoid driving through salt water.
Notes on operation
fActivate the Low Range program.
fSwitch the air conditioner off.
fSwitch the headlights off.Tips on driving
fAvoid high engine speeds (max. 2,500 rpm).
fDo not perform manual gear changes when
driving, and try to avoid stopping.
Moving off in the water can be difficult due to
the high resistance and the loose surface
involved.
fStart the water crossing at a shallow place at
walking speed.
fAfter checking the body of water, take the
shortest path through it.
fNever drive into the water at high speed. The
resulting “bow wave” could damage the engine
and its accessories.
fAdjust your driving style to the unfamiliar sur-
roundings.
fCross the body of water slowly and at a con-
stant speed.
fNever turn around when crossing a body of
water.
fIf it is not possible to cross the body of water,
the car must be backed out of it in reverse
gear.
The servo pump and alternator can fail if the car is
driven through water for an extended period.
fIf the servo pump fails, substantially more
force will have to be exerted in order to steer. Maintenance Note
The car requires a special check after the water
crossing.
fRemove mud from the tire tread.
fBriefly apply the brakes in order to dry them
after driving through the water.10_Cayenne_21_KW17.book Seite 200 Donnerstag, 9. April 2009 3:33 15

240
Parking Limits of ultrasonic measurement
– ParkAssist cannot detect sound-absorbing
obstacles (e.g. winter operation, powder
snow),
– Sound-reflecting obstacles (e.g. glass sur-
faces, flat painted surfaces),
– And very thin obstacles.
Other ultrasound sources (e.g. pneumatic brakes
of other vehicles, jackhammers) can interfere with
detection of obstacles.
Fault indication without warning tone
All red light segments of the active warning indica-
tors light up when there is a temporary fault in
ParkAssist.
Note
Correct operation is no longer ensured if there is
a temporary fault (e.g. caused by ice formation or
heavy soiling on the sensors).
The system detects the temporary fault.
All light segments light up until a speed of
9mph (14km/h) is reached.
ParkAssist is ready for operation again when the
interference has been eliminated.Fault indication with warning tone
In the event of a long-lasting fault in ParkAssist,
the red light segments of the active warning indi-
cators light up and a continuous tone sounds for
three seconds after a transmission range has
been selected.
Possible causes
– Defect or system fault.
fSwitch ParkAssist off.
When ParkAssist is switched off, the indicator
light in the button lights up.
Please see the chapter “SWITCHING
PARKASSIST ON AND OFF” on Page 237.
fPlease have the fault remedied at an
authorized Porsche dealer.Driving with a trailer
The ParkAssist rear monitoring area is switched
off when the trailer’s power supply is plugged in.
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Maintenance and Car Care
257
Brake-Fluid LevelfUse only new (unused) Original Porsche brake
fluid.
Further important information concerning “mainte-
nance” can be found in a separate chapter.
fPlease see the chapter “EXERCISE EXTREME
CAUTION WHEN WORKING ON YOUR VEHICLE”
on Page 250.
Warning!
Brake fluid is hazardous to your health, and
may be fatal if swallowed.
Brake fluid also attacks paintwork.
fKeep brake fluid out of children's reach.
fImmediately rinse off spilled brake fluid with
clean water.
fIf brake fluid gets into your eye, immediately
rinse with clean water for a few minutes. Then
see a doctor immediately.
fPlease note all the information on the refill container of the brake fluid.
Checking the brake-fluid levelThe reservoir for the hydraulic braking system is
located in the engine compartment.
1. Rotate the turn-locks 90° anti-clockwise
(arrow) with a screwdriver and remove the
cover.
2. Check brake-fluid level at the transparent
reservoir.
The fluid level should always lie between the
MIN and MAX marks.A slight decrease in the fluid level due to wear and
automatic readjustment of the disc brakes is
normal.
If, however, the fluid level falls markedly or below
the MIN mark, the braking system may have
developed a leak.
fPlease have the braking system checked
immediately at an authorized Porsche dealer.
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