2004 PORSCHE CAYENNE power steering

182
Driving and Driving Safety
Warning!
In spite of the advantages of PTM or four-wheel dri-
ve, 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 situ-
ation.
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 PTM or four-wheel drive.
Risks of accident due to inappropriate speed
cannot be reduced by PTM.Porsche Traction Management (PTM)Porsche Traction Management is a full-time all-
wheel control system designed to influence the
longitudinal and lateral dynamics. It is closely
linked with the Porsche Stability Management
(PSM) system:
PTM ensures the best possible power distribution
to the four driven wheels at the front and rear
axles. The system realizes this optimal traction by
intervening in the lock control function of the trans-
fer case and rear differential. PTM is active at all
times and, unlike the PSM, cannot be switched off.Advantages of PTM
– Obvious improvement in traction, driving
stability and steering ability of the car.
– Vehicle is more manageable when driven at its
performance limits.
– Improved straight-ahead tracking and stability.
– The aforementioned features allow for a
sportier setup of the running gear.
– The TCS and ABD provide even better traction
for all wheels.
Full-time all-wheel drive
With the four-wheel drive, the drive power is
variably distributed to the front and rear wheels.
Power distribution and wheel speed compensation
between the front and rear axles is realized with a
transfer box.
Distribution of the drive power depends on the
wheel speed difference between the two axles.
The transfer box always controls power distribu-
tion in such a way that optimal propulsion is achie-
ved, even on an unfavorable road surface.
Full-time four-wheel drive ensures optimal handling
and greater stability.Automatic brake differential (ABD)
The ABD system controls the front and rear axles
separately. If one wheel of an axle starts to spin,
it is braked so that the other wheel on the same
axle can be driven.
The ABD recognizes different driving states, and it
features control strategies adapted to these
states. In situations in which little propulsive power
is required, such as when the car moves off on a
level gravel surface, traction control already
becomes active at low engine speeds. If great
propulsive power is required, e.g. when moving off
on an uphill slope or for rapid acceleration, the
ABD is adapted accordingly.
A special off-road program is used in Low Range
mode.
Traction control system (TCS)
The traction control system prevents the wheels
from spinning by adjusting the engine power,
thereby ensuring good lane-holding ability and a
stable driving behavior.10_Cayenne_21_KW17.book Seite 182 Donnerstag, 9. April 2009 3:33 15

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
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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Luggage Compartment, Loadspace and Storage
219
Compact disc player
Caution!
To avoid damage to compact disc player and
discs.
fUse only compact discs labeled as shown,
having no dirt, damage or warpage.
fNever attempt to disassemble or oil any part
of the player unit. Do not insert any object
other than a disc into the slot.Remember there
are no user-serviceable parts inside the
compact disc player.
fDo not allow the disc to sustain any finger-
prints, scrapes or stickers on the surfaces.
This may cause poor sound quality.
Hold the disc only on the edge or center hole.
fWhen not in use, take the disc out of the player,
put the disc back into its case and store it
away from dust, heat, damp and direct sun-
light.
Leaving the disc on the dashboard in the sun
can damage the disc.fIf the disc gets dirty, clean the disc by wiping
the surfaces from the center to the outside in
a radial direction with a soft cloth.
Do not use a conventional record cleaner or
anti-static record preservative.
Disc cleaners are available in audio stores.
Car Telephone and Aftermarket Alarms Important legal and safety information
regarding the use of cellular telephones
Some states may prohibit the use of cellular tele-
phones while driving a vehicle. Check the laws and
regulations on the use of cellular telephones in the
areas where you drive.
Danger!
Risk of an accident.
Severe personal injury or death can result in
the event of an accident.
Looking away from the road or turning your
attention away from your driving can cause
an accident and lead to serious personal
injury or death.
When using your cellular telephone, you should
always:
fGive full attention to your driving - pull off the
road and park before making or answering a
call if traffic conditions so require; andfKeep both hands on the steering wheel - use
hands-free operation (if available) - pull off the
road and park before using a hand-held tele-
phone.
It is essential to observe the telephone
manufacturer's instructions before operating
the telephone.
Any portable telephone or radio transmitter which
is used in a Porsche must be properly installed in
accordance with the technical requirements of
Porsche.
The transmission power must not exceed
10 W.
The devices must possess a type approval for
your vehicle and have an “e” symbol.
If you should require equipment with transmission
power values greater than 10 W, please consult
your authorized Porsche dealer for this purpose.
He is familiar with the technical requirements for
installing devices of this kind.
The antennas for all radios and telephones with a
transmitting antenna must be externally mounted.
The improper installation of radios or telephones
or use of a radio or telephone with a transmitting
antenna inside the car may cause the warning
lights to come on.
Improper installation of such equipment can
create a discharged battery or excessive current
draw from added equipment.
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Maintenance and Car Care
249 Maintenance and Car Care
Exercise Extreme Caution
when Working on your Vehicle ..................... 250
Engine Oil .................................................. 251
Checking Engine Oil Level ........................... 252
Topping up Engine Oil ................................. 253
Coolant Level ............................................. 255
Brake-Fluid Level ........................................ 257
Washer Fluid .............................................. 258
Power Steering .......................................... 259
Changing Air Cleaner.................................. 260
Changing Particle Filter ............................... 260
Automatic Transmission Fluid ...................... 260
Manual Transmission Oil ............................. 260
Wiper Blades ............................................. 261
Emission Control System ............................ 263
How Emission Control Works ...................... 264
Fuel Economy ............................................ 265
Operating Your Porsche in other Countries ... 266
Fuel........................................................... 266
Portable Fuel Containers ............................. 268
Fuel Recommendations............................... 269
Fuel Evaporation Control ............................. 270
Car Care Instructions.................................. 270
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Maintenance and Car Care
259
Power Steering
Warning!
Risk of accident resulting in serious personal
injury or death. When the engine is stationary
(e.g. when on tow) or the hydraulic system
fails, there is no assistance for steering.
Therefore, substantially more force will have
to be exerted.
fExercise great care when on tow.
fHave the fault remedied at your nearest authorized Porsche dealer.
The flow noise heard at full steering lock is design-
related and does not indicate a defect in the
steering system.
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.
Checking hydraulic fluidfUse only hydraulic fluid authorized by
Porsche.
fCheck the fluid level with the engine stopped
and cold (engine temperature approx. 68 °F or
20 °C).
1. Remove cover A.2. Open the reservoir cap.
3. The fluid level should lie between the MIN and
MAX marks on the dipstick.
Add hydraulic fluid if necessary.
4. Close cap carefully.
5. Put on cover A.
6. Close engine compartment lid.
Note on operation
fIf the fluid level drops significantly, please have
the cause remedied immediately by an
authorized Porsche dealer.
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Minor Repairs
315
Fuse assignment – fuse box in left side of dashboardNo. Designation Rating in A No. Designation Rating in A1
Cockpit socket at front centre, centre console sockets
at rear right and rear left
20
24
Tire Pressure Monitoring
5
2 Parking heater radio receiver 5 26Engine control unit (engine management, radiator fans,
airbag, clutch switch, instrument panel)10
3
Socket in passenger footwell
20
30
Off-road roof-mounted headlights
15
4 Parking heater 20 31
Off-road roof-mounted headlights15
5
Sockets in luggage compartment
20
33
Steering column module
15
7 Diagnostic socket, rain sensor 5 34 Passenger compartment monitoring 5
8
Wiper motor for windshield
30
35
Vehicle electrical system control unit (right fog light,
right additional high beam, interior light)
30
9Vehicle electrical system control unit
(pump for washer fluid)15 36 Control unit for power seat controls, left 30
10
Power window and central locking, rear left door
30
39
Heated rear window relay (control)
5
14 Power window and central locking, front left door 30 40 Instrument panel, diagnosis 5
15
Tail light, right
15
41
Kessy control unit (steering column lock, ignition lock,
Porsche Entry & Drive, clutch switch)
15
16 Vehicle electrical system control unit (horn) 20 42Sliding/lifting roof or Panorama roof system 30
17
Vehicle electrical system control unit (left turn signal
light, right side marker light, left low beam)
30
43
Subwoofer
30
18 Headlight washer system 25 44
Electrical seat adjustment, left30
19
Vehicle electrical system control unit (interior light)
5
45
Seat heating, rear
25
20Vehicle electrical system control unit (instrument
lighting, fog light left, left additional high beam)30 47 Rear differential lock 10
22
Rear differential lock, automatic rear lid
30
49
Servotronic
5
23 Differential lock 10 51 Air-quality sensor, diagnostic socket, parking brake 5
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