four wheel drive Alfa Romeo 166 2006 Owner handbook (in English)

The heart of the VDC system is a sensor
that originates from the field of aeronau-
tics, which detects rotations of the car
around its vertical axis. The centrifugal
forces generated when the car runs on a
bend are detected by a highly sensitive,
lateral acceleration sensor.
The stabilising action of the VDC system
is based on calculations made by the
system’s electronic control unit which
processes the signals received from the
steering wheel rotation, lateral accelera-
tion and individual wheel rotation sen-
sors. These signals allow the control unit
to recognise the manoeuvre the driver in-
tends to do when turning the steering
wheel.
118
VDC SYSTEM OPERATION
The VDC system turns on automatically
when the car is started and cannot be
switched off. It is however possible to cut
off operation of the ASR system pressing
the corresponding button on the centre
console.
The main components of the VDC sys-
tem are:
– an electronic control unit which
processes the signals received from the
various sensors and brings about the
most appropriate strategy;
– a sensor that detects the position of
the steering wheel;
– four sensors that detect the rotation
speed of each wheel;
– a sensor that detects rotation of the
car around the vertical axis;
– a sensor that detects lateral accelera-
tion (centrifugal force).The control unit processes the informa-
tion received from the sensors and is
therefore capable of detecting the posi-
tion of the car and comparing it with the
trajectory the driver would like to follow
instant by instant. In the event of a dis-
crepancy, the control unit chooses and
commands the most suitable action to
bring the car back to the required course
within a fraction of a second: braking one
or more wheels at a different braking
force and, if necessary it reduces the
power transmitted by the engine.
The corrective actions are changed and
controlled continuously until the car re-
turns to the required course.
The action of the VDC system consider-
ably increases the active safety of the ve-
hicle under many critical situations and it
is particularly useful also when the road
surface grip conditions change.

147
WINTER TYRES
These tyres are specially designed for
driving on snow and ice, to be fitted in re-
placement of those fitted on the car.
Use winter tyres of the same size as the
normal tyres provided on the car.
Alfa Romeo Authorised Services will be
pleased to advise you on the choice of
the car most suited to the use the Cus-
tomer intends to make of it.
For the type of tyre to be used, inflation
pressures and the specifications of winter
tyres, follow the instructions given in the
“Technical Specifications” chapter.
The winter features of these tyres are
reduced considerably when the tread
depth is below 4 mm. In this case, they
should be replaced.
Due to the winter features, under nor-
mal conditions of use or on long motor-
way journeys, the performance of these
tyres is lower than that of normal tyres.
It is necessary therefore to limit their
use to the purposes for which they are
certified.WARNINGWhen winter tyres are
used with a maximum speed index below
the one that can be reached by the vehi-
cle (increased by 5%), place a notice in
the passenger compartment, plainly in
the driver’s view which states the maxi-
mum permissible speed of the winter
tyres (as per CE Directive).
Fit the same type of tyre on all four
wheels (brand and profile) to ensure
higher driving safety when braking and
good handling.
Remember that it is inappropriate to
change the direction of rotation of tyres.
SNOW CHAINS
Use of snow chains should be in compli-
ance with local regulations. Snow chains
should only be applied to the drive
wheels (front). The sport connotation of
the vehicle requires the use of specific
types of snow chain. Alfa Romeo Autho-
rized Services should first be contacted
before purchasing or using snow chains.
Check the tension of the chain after the
first few dozen metres have been driven.
IMPORTANTWhen driving on snow
with snow chains fitted, it might be
helpful to turn off the ASR function of
the VDC system (if present): in fact, in
these conditions, skidding of the driving
wheels when moving off makes it pos-
sible to obtain higher traction.

158IN THE EVENT
OF A PUNCTURE
Wheel changing and cor-
rect use of the jack and
spare wheel call for some precau-
tions as mentioned below.
Signal the presence of the station-
ary vehicle according to current
regulations: hazard warning lights,
reflecting triangle, etc.
Any passengers should leave the
car, specially if the vehicle is heav-
ily laden, and wait for the wheel
to be changed out of harm of the
traffic.
If parked on a slope or rough road,
place wedges or other suitable de-
vices under the wheels to prevent
the car from rolling. Do not grease
the threads of bolts before in-
stalling them; they might slip out.
WARNING
The spare wheel is specific
to your model of car: do
not use it on another model or use
the spare wheel of other models on
your car. On cars fitted with tyres
215/55 R16 (*), 225/45 R17,
235/40 R18 and spare wheel with
tyre 215/55 R16 (*), since the
spare wheel is different from the
standard wheels, observe the in-
structions for use given below:
– The spare wheel should only be
used in an emergency.
– Use of the spare wheel should
be kept to a minimum. Do not
drive at speeds of over 80 km/h.
– The car will handle differently
when the spare wheel is fitted.
Avoid sudden acceleration or brak-
ing, sharp corners and fast bends.
– Check at regular intervals that
spare wheel pressure is equal to
2.7 bar (2.7 kg/cm
2).
– Two or more spare wheels
should never be used together.
Have the wheel changed repaired
and refitted as soon as possible.
WARNING
On cars fitted with tyres
215/55 R16 (*), 225/
45 R17, 235/40 R18 and spare
wheel with tyre 215/55 R16 (*),
do not apply the wheel cap on the
spare wheel. The spare wheel has
an orange sticker with the main
cautions about use of the wheel it-
self and instructions for use.
The sticker must absolutely never
be removed or covered.
The sticker contains the following
instructions in four languages:
– WARNING! Only for temporary
use 80 km/h max!
– Replace with standard service
wheel as soon as possible.
– Do not cover these instructions.
The vehicle may fall if the jack is
not positioned correctly.
WARNING
(*) Tyre 205/55 R16 for versions/mar-
kets where applicable.