2004 PORSCHE CAYENNE wheel

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The ignition key can be withdrawn only in selector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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172
Driving and Driving Safety The corner is taken in the right gear, and when you
accelerate out of the corner you do not have to
change down.
Shifting gear on the steering wheel
By shifting gear with the rocker switches on the
steering wheel, you can temporarily change from
automatic selection mode D to manual selection
mode M.
Advantages:
– Shifting down before corners and on entering
congested areas, on downward slopes (engine
braking) or for brief spurts of acceleration.
– Selecting 1st or 2nd gear for moving off.
The manual selection mode remains engaged:
– For cornering (depending on the lateral
acceleration) and passing,
– When the vehicle is stationary (e.g. at a
junction).
The system leaves manual selection mode:
– automatically after around 8 seconds
(unless car is cornering, passing or
stationary),
– if you depress the accelerator to kickdown.Temporary change-down
Precondition:
– Speed is higher than approx. 33 mph
(54 km/h).
fDepress accelerator quickly.
The Tiptronic changes temporarily to the
sportiest gear-changing map, i.e. to the
highest possible gear-changing points.
Correspondingly, the transmission shifts down
immediately by one, two or three gears.
Ending the function
fRelease the accelerator markedly (by approx.
25%).
Kickdown
The kickdown function is active in selector lever
position D.
fFor optimum acceleration, e.g. when over-
taking, depress the accelerator pedal beyond
the full-throttle point (kickdown).
The transmission shifts down depending on the
speed of travel and engine speed.
Upward shifts occur at the highest possible engine
speeds.
These gear-changing speeds remain active until
the accelerator is released to approx. 80% of the
full-throttle position.
D - Automatic selection mode (in the off-
road driving program)fUse selector lever position D for “normal”
driving.
The gears are shifted automatically according
to the accelerator position and speed.
The gear-changing points have been adjusted to
achieve the best possible vehicle control on diffi-
cult terrain.
Depending on the route profile, the gear-changing
points are shifted towards higher or lower engine-
speed ranges. On steep downhill stretches,
upward shifts are prevented until medium engine
speeds are reached (at least 2,500 rpm).
When the car is passing, an automatic upshift
does not occur when the engine speed limit is
reached.
Shifting gear on the steering wheel
By shifting gear with the rocker switches on the
steering wheel, you can temporarily change from
automatic selection mode D to manual selection
mode M.
Advantages:
– Shifting down on downward slopes (engine
braking) or for brief spurts of acceleration.
– Selecting 1st/2nd or 3rd gear for moving off.
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Driving and Driving Safety
175
ParkingfGo easy on the accelerator.
fWhen parking or maneuvring in a small space,
control the speed by careful use of the foot-
brake.Driving in winterIn wintry road conditions it is advisable to take
steep inclines in manual mode M. This prevents
the occurrence of gear changes that could cause
wheelspin.
Limp-home modeIf there is a fault in the transmission:
–An X appears instead of the current gear
indicator on the multi-purpose display of the
instrument panel.
The transmission no longer shifts.
fTo remedy the fault, immediately consult an
authorized Porsche dealer.
Warning!
Reverse gear lock monitoring is disabled in
the emergency running program.
Damage to the vehicle may result as well as
loss of control, if the vehicle is moving for-
ward fast enough to cause rear wheel lockup.
fDo not shift into R while the vehicle is moving forward.
Tip on driving
3rd or 5th gear in selector position D and reverse
gear R are now available and will allow you to
reach the nearest authorized Porsche dealer.
fPlease go to your authorized Porsche dealer
as soon as possible.
Selector lever emergency releaseIn the event of an electrical fault, the selector lever
lock in position P can be manually released (for
towing the vehicle, for example).
1. Fold up armrest.
2. Remove key B from the lower storage tray
(underneath the rubber mat) in the center
console.
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178
Driving and Driving Safety Selecting off-road driving program
fPush rocker switch forward .
The vehicle becomes one step more suitable
for off-road driving.
Selecting on-road driving program
fPull rocker switch to the rear .
The vehicle becomes one step more suitable
for on-road driving.
Once the driving program has been selected, the
rocker switch springs back to home position.
A-High Range on-road driving program
(without reduction)
B-Low Range off-road driving program
(with reduction)
C-Center differential lock in Low Range is fully engaged
D-Rear differential lock in Low Range is fully engagedDisplay of the selected driving program
The selected driving program is displayed by light-
emitting diodes next to the rocker switch (illustra-
tion).
The corresponding indicator lights on the instru-
ment panel and light-emitting diodes beside the ro-
cker switch flash several times during the shif-
ting process.Tip on driving center differential lock
When the center differential lock C is fully enga-
ged, there is no longer any speed difference bet-
ween the front and rear axles. If, for example, both
wheels at the front axle lose traction on an icy
road or soft surface, the rigidly linked drive wheels
will permit the car to continue moving neverthe-
less.
Tip on driving rear-differential lock
When the rear differential lock D is fully engaged,
there is no longer any speed difference between
the two rear wheels. If, for example, one drive
wheel at the rear axle loses traction on an icy road
or soft surface, the rigidly linked drive wheels will
permit the car to continue moving nevertheless.
Note on operation
The rear differential lock can be engaged only
while the engine is running.
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Driving and Driving Safety
181
Power-Transmission and Running-Gear Control SystemsA complex interconnection of all control systems acting in power transmission and in the running gear has been realized in your Porsche.
All control systems have been linked with the aim of combining the best possible driving performance with maximum safety.
The following systems are involved:
System/designation Scope
PTM
Porsche Traction Management– Full-time all-wheel drive
– Electronically controlled center differential lock
– Automatic brake differential (ABD)
– Traction control system (TCS)
– Reduction gear/Low Range
PTM Plus
Porsche Traction ManagementIn addition to the PTM features, PTM Plus also includes:
– Electronically controlled rear differential lock
PSM
Porsche Stability Management– Stability management system
– Anti-lock brake system (ABS)
– Brake system prefilling
– Brake booster
– Traction control system (TCS)
– Automatic brake differential (ABD)
– Engine drag torque control (MSR)
Air suspension
with level control and height adjustment– Fully load bearing air spring struts with integral shock absorbers
– Air supply system with pressure accumulator
PAS M
Porsche Active Suspension Management– Shock absorber system with adaptive, continuous shock absorber control
PDCC
Porsche Dynamic Chassis Control– Active chassis control system to stabilize roll tendency of vehicle body when driving
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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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