2004 PORSCHE CAYENNE differential

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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186
Driving and Driving Safety Collapsible spare wheel
fNever switch the PSM off when driving with a
collapsible spare wheel.
To w i n g
fFor information on towing:
Please see the chapter “TOWING” on
Page 342.
Tip on driving
When PSM is switched off, wheel-specific brake
interventions and the traction control system
(TCS) are also inactive.
The automatic brake differential (ABD) remains on.
Switching PSM back onfPress PSM OFF button A.
PSM is switched on after a short delay.
The light-emitting diode in the button and the
multi-functional PSM light on the instrument
panel go out. A message is shown on the multi-
purpose display of the instrument panel.
ABS
(Anti-lock Brake System)
Warning!
In spite of the advantages of ABS, 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 ABS.
Risks of accident due to inappropriate speed can-
not be reduced by ABS.
ABS ensures:
–Full steering control
The vehicle remains steerable
–Good driving stability
No skidding due to locked wheels
–Optimum braking distance
Shorter stopping distances in most cases
–Lock prevention
No flat spots on the tiresFunction
The decisive advantage of ABS is in the driving
stability and maneuvrability of the vehicle in
hazardous situations.
ABS prevents locking of the wheels during full
braking, on almost all road surfaces, until shortly
before the vehicle stops.
The ABS begins to control the braking process as
soon as a wheel shows a tendency to lock.
This controlled braking process is comparable to
extremely rapid cadence braking.
The pulsating brake pedal and a “rattling noise”
warn the driver to adapt her/his driving speed to
the road conditions.
fIf full braking should be necessary, press the
brake pedal all the way down throughout the
entire braking procedure, regardless of the
pulsating pedal. Do not ease up on pressure
applied to the pedal.
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196
Driving and Driving Safety
Driving systems for off-road drivingSpecially adapted driving programs or power-
transmission and running-gear control systems
are available for off-road driving:
– Off-road program Low Range
–Off-road PSM
–Off-road ABS
– Center differential lock
– Rear differential lock
fPlease see the chapter “POWER-TRANSMISSI-
ON AND RUNNING-GEAR CONTROL SYSTEMS”
on Page 181.Before driving offTires
fCheck tread depth and tire pressure.
fCheck for damage and remove any foreign
objects (e.g. stones) from the tread.
fReplace missing valve caps.
Rims
fReplace dented or damaged rims before
driving off road.
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.
After driving off roadOff-road driving places a greater burden on the
vehicle than does normal driving on roads.
We recommend inspecting the vehicle after off-
road driving. Potential damage poses an accident
risk and impairs driving comfort. Damage on the
car is recognized in good time if the car is
checked.
Caution!
Car damage poses an accident risk for the
vehicle occupants and other road users.
fIn cases of doubt, have your vehicle checked
by your authorized Porsche dealer.
fExamine tires for signs of damage such as
cuts, tears, bulges or foreign objects stuck in
the tread.
Replace a damaged tire if necessary.
fHave any damage to your vehicle repaired by an authorized Porsche dealer without delay.
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198
Driving and Driving Safety Note on operation
fActivate the Low Range program before taking
extreme upward or downward gradients.
Tips on driving
fDo not perform manual gear changes when
driving, and try to avoid stopping.
fAvoid high engine speeds (max. 2,500 rpm).
Traction on uphill slopesNote on operation
fActivate the Low Range program and engage
differential locks if necessary.
Tips on driving
fWhen driving uphill, go easy on the accelerator
and make sure that wheels have sufficient
traction (don't spin).
fAvoid high engine speeds (max. 2,500 rpm).
fDrive slowly.
Driving downhill
Danger!
There is a danger of serious personal injury
or death and risk of damage if the vehicle
should overturn.
fDo not drive over embankments or slopes at
steep diagonal angles.
fDrive downhill slowly, with the wheels pointing
straight ahead.
fIf the vehicle starts to tilt, immediately steer in
the direction of the tilt (line of slope).
fWhen driving downhill, never let the vehicle roll
when in idle.
fUse engine braking effect.
If the engine braking effect is not adequate, gently apply the foot brake.Note on operation
fActivate the Low Range off-road driving
program. The off-road ABS is switched on
automatically.
Tips on driving
fDo not perform manual gear changes when
driving, and try to avoid stopping.
fAvoid high engine speeds (max. 2,500 rpm).
A special circuit in the off-road ABS permits con-
trolled brief lock-up of the front wheels so that they
can dig into the loose surface more effectively.
Locked wheels slip and can no longer be steered.
fWhen driving down steep hills on unpaved
surfaces, brake carefully so that vehicle does
not start to slide.
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Driving and Driving Safety
199
ObstaclesfPay attention to the ground clearance of the
car.
Please see the chapter “GROUND
CLEARANCE” on Page 357.
Note on operation
fActivatethe Low Range program and engage
differential locks if necessary.
Tips on driving
fJust before reaching the obstacle, ease off the
accelerator slightly and use the car's momen-
tum to cross the obstacle. This will prevent the
car from jumping over the obstacle and landing
on the following downward slope at an exces-
sive speed.
fAvoid high engine speeds (max. 2,500 rpm).
Water crossingfPay attention to the ground clearance of the
car.
Please see the chapter “GROUND
CLEARANCE” on Page 357.
Danger!
Danger of drowning if water enters the
vehicle. Risk of damage to the engine and
accessories if water penetrates.
fBefore driving through water, check the water
depth A, water speed and the condition of the
surface beneath it.
Cayenne, Cayenne S, Cayenne S
Tr a n s s y b e r i a :
The water must not be deeper than 19.7 in.
(50 cm).
The water must not be deeper than 21.9 in.
(55.5 cm) for vehicles with level control and
height adjustment.
Cayenne GTS:
The water must not be deeper than 18.7 in.
(47.6 cm).
The water must not be deeper than 21.1 in.
(53.5 cm) for vehicles with level control and
height adjustment.
fCheck the door sills and rubber seals before
starting to drive.
fDo not drive through deep or rapidly flowing
water.
Deep or rapidly flowing water, e.g. mountain
streams, can cause the car to deviate from the
desired path.
fAvoid a "bow wave" by driving at an appropriate
speed.
fNever open the doors when driving through
water.
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Driving and Driving Safety
201
Crossing obstacles
Caution!
Risk of damage to the underbody and chas-
sis components if obstacles are traversed
improperly.
fAlways bear in mind the ground clearance of
your vehicle.
fSlowly drive over the middle of tree trunks,
boulders or other obstacles with one of the
front wheels.
fCross the obstacle with the rear wheel in the same way.
Note on operation
fActivate Low Range and engage differential
locks if necessary.Tips on driving
fHave your passenger direct you if necessary.
fAvoid high engine speeds (max. 2,500 rpm).
fDrive slowly.
Driving on sandNote on operation
fActivate Low Range and engage differential
locks if necessary.
Tips on driving
Loose sand is an especially tricky surface for off-
road driving.
You can often become stuck in sand within
minutes if you do not drive correctly in such
situations.
fDrive at brisk pace and do not stop under any
circumstances. This will reduce the chance of
the car becoming bogged down.
fFollow existing tracks – provided that they
have not been covered by blown sand, are not
too deep and the car's ground clearance is
sufficient.
Pay attention to the ground clearance of the
car.
Please see the chapter “GROUND
CLEARANCE” on Page 357.
fAvoid high engine speeds (max. 2,500 rpm).
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202
Driving and Driving Safety When driving on slopes with soft sand on vehicles
with Tiptronic S:
fUse the manual select mode M in addition to
the Low Range program.
If your vehicle becomes stuck nevertheless:
fDo not spin the wheels. Instead, use branches,
mats or similar items to provide adequate
traction so that you can drive out of the critical
area.
Track rutsOther vehicles leave ruts in many off-road courses
or gravel roads.
fPay attention to the ground clearance of the
car.
Please see the chapter “GROUND
CLEARANCE” on Page 357.
Caution!
Risk of damage to the vehicle floor when
driving through ruts that are too deep.
fAlways bear in mind the car's ground clearan-
ce.
fDo not drive over ruts that are too deep.
Note on operation
fActivate the Low Range program and engage
differential locks if necessary.
Tips on driving
fIn cases of doubt, drive with one wheel on the
strip of grass between the ruts.
fAvoid high engine speeds (max. 2,500 rpm).
fDrive slowly.
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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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