2006 SUBARU IMPREZA traction control

Starting and operating 7-13
– CONTINUED –
The driver’s control center differential al-
lows you to freely change the degree of
limitation of the differential action (limited
slip differential (LSD) torque) of your vehi-
cle ’s center differential.
By using the center differential control di-
al, you can set an initial LSD torque to
match the road surface conditions, driving
conditions and your driving style.
1) LSD torque
2) Traction torque
A) Initial LSD torque (adjustable)
B) Mechanical LSD torque
NOTE
If you rapidly depress and release the
accelerator pedal while driving at low
speed, you may hear a knocking sound
from the vicinity of the center differen-
tial and rear differential. This sound oc-
curs because of the structure of the
center differential. It does not indicate
a problem.
Auto mode
In the auto mode, the system estimates
the driving and road conditions using sig-
nals from the wheel speed sensor, throttle
position sensor, steering angle sensor
and brake switch, etc. According to the re-
sult, it electronically and automatically
controls the degree of limitation of the dif-
ferential action (LSD torque) to optimize
the differential action of the center differ-
ential. When the ignition switch is turned
ON, the “AUTO ” indicator light in the com-
bination meter comes on. The system can
be switched to a manual mode.
Manual mode
In the manual mode, you can use the cen-
ter differential control dial to adjust the ini-
In the event of failure of the driver
’s
control center differential, the “ ”
indicator light will flash. Have the
vehicle inspected by your SUBARU
dealer.
700378
LOCK1
2A
B
700123

Starting and operating 7-15
Turn the dial rearward to reduce the initial
LSD torque; when the white line reaches
the rearmost position, the initial LSD
torque will be minimum and the “ ” indi-
cator light will come on. Under this condi-
tion, only the Mechanical LSD torque will
limit the differential action.
NOTE
A higher initial LSD torque setting
gives the vehicle greater traction when
driving straight ahead but makes cor-
nering more difficult. Remember this
when adjusting the initial LSD torque.
In general, higher initial LSD torque
settings assist driving on slippery
roads and lower settings for non-slip-
pery roads. If you become stuck in
snow or mud, turning the center differ-
ential control dial to the frontmost po-
sition will help move the vehicle out.
(The “LOCK ” indicator will come on at
the frontmost position.)
During cornering or when making
turns (especially when getting into the
garage), the rotational difference be-
tween the front and rear wheels may
cause a braking effect accompanied by vibration and noise. This does not indi-
cate a problem. The phenomenon will
disappear when you turn the center dif-
ferential control dial to the rearmost
position (minimum initial LSD torque
position).
Use the center-differential indicator
light only as a rough indication of the
initial LSD torque.
If you operate the center differential
control dial while quickly accelerating
or turning a tight corner, you may feel
slight shocks. This is due to differential
action by the center differential and
does not indicate a problem.
Temporary release
When the driver stops the vehicle and
pulls the parking-brake lever after manual-
ly setting the initial LSD torque, the LSD
torque is temporarily minimized. However
the indicator in the combination meter
continues to show the driver ’s selected ini-
tial LSD torque. When the driver releases
the parking-brake lever, the initial LSD
torque set by the driver is restored.
Do not turn the control dial when
a wheel slippage occurs. Wait un-
til the wheelspin has been
brought under control.
700358
Under any of the following condi-
tions, turn the center differential
control dial to the rearmost posi-
tion to minimize the initial LSD
torque:
When a temporary spare tire is
installed
When your vehicle is towed
When the vehicle is stopped
with the manual mode selected

Driving tips 8-11
– CONTINUED –
Your vehicle is equipped with
“all season
tires ” as original equipment, which are de-
signed to provide an adequate measure of
traction, handling and braking perfor-
mance in year-round driving. In winter, it
may be possible to enhance performance
through use of tires designed specifically
for winter driving conditions.
When you choose to install winter tires on
your vehicle, be sure to use the correct tire
size and type. You must install four winter
tires that are of the same size, construc-
tion, brand and load range and you should
never mix radial, belted bias or bias tires
since this may result in dangerous han-
dling characteristics. When you choose a
tire, make sure that there is enough clear-
ance between the tire and vehicle body.
Remember to drive with care at all times
regardless of the type of tires on your ve-
hicle.
WRX-STIYour vehicle is equipped with “summer
tires ” as original equipment, which are in-
adequate for driving on slippery roads
such as on snow-covered or icy roads.
Compared with winter and all-season
tires, summer tires give significantly less
grip on snowy and icy road surfaces.
Therefore, use of winter tires is strongly
recommended when driving with such
road conditions.
When you choose to install winter tires on
your vehicle, be sure to use the correct tire
size and type. You must install four winter
tires that are of the same size, construc-
tion, brand and load range and you should
never mix radial, belted bias or bias tires
since this may result in dangerous han-
dling characteristics. When you choose a
tire, make sure that there is enough clear-
ance between the tire and vehicle body.
Remember to drive with care at all times
regardless of the type of tires on your ve-
hicle.
Tire chains
Driving on snowy grades or icy roads may
require the use of tire chains, in which
case put the chains on the front wheels
only. Use only SAE class S type chains
that are of the correct size for your tires so
as not to damage the vehicle body or sus-
Do not use a combination of radi-
al, belted bias or bias tires since it
may cause dangerous handling
characteristics and lead to an ac-
cident.
When replacing original tires with
winter (snow) tires, make sure you
use only the same size, construc-
tion and load range as the original
tires listed on the tire placard. Us-
ing other sizes and construction
may affect speedometer/odome-
ter calibration and clearance be-
tween the body and tires. It also
may be dangerous and lead to
loss of vehicle control.
You must install four winter tires
that are of the same size, con-
struction, brand, and load range.
Mixing other sizes or construc-
tions may result in severe me-
chanical damage to the drive train
of your vehicle and may affect
ride, handling, braking and speed-
ometer/odometer calibration. It
also may be dangerous and lead
to loss of vehicle control.
Do not use a combination of radi-
al, belted bias or bias tires since it
may cause dangerous handling
characteristics and lead to an ac-
cident.

13-12 Consumer information and Reporting safety defects
Uniform tire quality grading
standards
This information indicates the relative
performance of passenger car tires in
the area of treadwear, traction, and
temperature resistance. This is to aid
the consumer in making an informed
choice in the purchase of tires.
Quality grades can be found where
applicable on the tire sidewall be-
tween tread shoulder and maximum
section width. For example:
Treadwear 200 Traction AA Tem-
perature A
The quality grades apply to new pneu-
matic tires for use on passenger cars.
However, they do not apply to deep
tread, winter type snow tires, space-
saver or temporary use spare tires,
tires with nominal rim diameters of 12
inches or less, or to some limited pro-
duction tires.
All passenger car tires must confirm
to Federal Safety Requirements in
addition to these grades.
Treadwear
The treadwear grade is a comparative
rating based on the wear rate of the
tire when tested under controlled con-
ditions on a specified government test
course.
For example, a tire graded 150 would
wear one and one-half (1-1/2) times
as well on the government course as
a tire graded 100. The relative perfor-
mance of tires depends upon the ac-
tual conditions of their use, however,
and may depart significantly from the
norm due to variations in driving hab-
its, service practices and differences
in road characteristics and climate.
Traction AA, A, B, C
The traction grades, from highest to
lowest, are AA, A, B and C. Those
grades represent the tire ’s ability to
stop on wet pavement as measured
under controlled conditions on speci-
fied government test surfaces of as-
phalt and concrete. A tire marked C
may have poor traction performance.
Temperature A, B, C
The temperature grades are A (the
highest), B, and C, representing the
tire ’s resistance to the generation of
heat and its ability to dissipate heat
when tested under controlled condi-
tions on a specified indoor laboratory
test wheel. Sustained high tempera-
ture can cause the material of the tire
to degenerate and reduce tire life, and
excessive temperature can lead to
sudden tire failure. The grade C corre-
sponds to a level of performance
which all passenger car tires must
meet under the Federal Motor Vehicle
Safety Standards No. 109. Grades B
and A represent higher levels of per-
formance on the laboratory test wheel
than the minimum required by law.
The traction grade assigned to
this tire is based on straight-
ahead braking traction tests,
and does not include accelera-
tion, cornering, hydroplaning, or
peak traction characteristics.