2006 SUBARU IMPREZA wheel

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

7-16 Starting and operating
Automatic transmission
The automatic transmission is electroni-
cally controlled with 4-forward speeds and
1-reverse speed.
NOTE
When the engine coolant tempera-
ture is still low, your vehicle ’s automat-
ic transmission will up-shift at higher
engine speeds than when the coolant
temperature is sufficiently high in or-
der to shorten the warm-up time and
improve driveability. The gearshift tim-
ing will automatically shift to the nor-
mal timing after the engine has warmed
up.
Immediately after ATF (automatic
transmission fluid) is replaced, you
may feel that the automatic transmis-
sion operation is somewhat unusual.
This results from invalidation of data
the on-board computer has collected
and stored in memory to allow the
transmission to shift at the most ap-
propriate times for the current condi-
tion of your vehicle. Optimized shifting
will be restored as the vehicle contin-
ues to be driven for a while.
Selector lever for automatic
transmission
Do not shift from the “P ” or “N ” po-
sition into the “D ”, “3 ”, “2 ”, “1 ” or
“ R ” position while depressing the
accelerator pedal. This may cause
the vehicle to jump forward or back-
ward.
Shift into the “P ” or “R ” position
only after the vehicle is complete-
ly stopped. Shifting while the ve-
hicle is moving may cause dam-
age to the transmission.
Do not race the engine for more
than five seconds in any position
except the “N ” or “P ” position
when the brake is set or when
chocks are used in the wheels.
This may cause the automatic
transmission fluid to overheat.
Avoid shifting from one of the for-
ward driving positions into the “ R ” position or vice versa until the
vehicle has completely stopped.
Such shifting may cause damage
to the transmission.
When parking the vehicle, first se-
curely apply the parking brake
and then place the selector lever
in the “P ” position. Avoid parking
for a long time with the selector le-
ver in any other position as doing
so could result in a dead battery.
700034

Starting and operating 7-17
– CONTINUED –
: With the brake pedal depressed,
move the lever along the gate.
: Move the lever along the gate.
The selector lever has seven positions.
P (Park)
This position is for parking the vehicle and
starting the engine.
In this position, the transmission is me-
chanically locked to prevent the vehicle
from rolling freely.
When you park the vehicle, first set the
parking brake fully, then shift into the “P ”
position. Do not hold the vehicle with only
the transmission.
A shift interlock function is employed in
the automatic transmission system to en- sure safe starting of the vehicle.
To shift the selector lever from the
“P ” to
the any other position, you have to de-
press the brake pedal fully when the igni-
tion switch is in the “ON ” position. This
prevents the vehicle from lurching when it
is started.
If the shift lever does not move from the “ P ” position with the brake pedal de-
pressed, refer to the “Shift lock release ”
section in this chapter.
R (Reverse)
This position is for backing the vehicle.
To shift from the “N ” to “R ” position, first
stop the vehicle completely then move the
lever to the “R ” position.
N (Neutral)
This position is for restarting a stalled en-
gine.
In this position the wheels and transmis-
sion are not locked. In this position, the
transmission is neutral; the vehicle will roll
freely, even on the slightest incline unless
the parking brake or foot brake is on.
Avoid coasting with the transmission neu-
tral.
During coasting, there is no engine brak-
ing effect.
NOTE
If you stop the engine with the selector
lever in the “N ” position, move the se-
lector lever to the “P ” position immedi-
ately. Otherwise, you may find that the
selector lever soon cannot be moved
to the “P ” position. If you find that the
selector lever cannot be moved from
the “N ” position to the “P ” position,
turn the ignition switch to the “ON ” po-
sition and try again.
D (Drive)
This position is for normal driving.
The transmission automatically shifts into
a suitable gear from 1st to 4th according to
the vehicle speed and the acceleration
you require.
When more acceleration is required in this
position, press the accelerator pedal fully
to the floor and hold that position. The
transmission will automatically downshift
to 3rd, 2nd or 1st gear. When you release
the pedal, the transmission will return to
700332
Do not drive the vehicle with the se-
lector lever in the “N ” (neutral) posi-
tion. Engine braking has no effect in
this condition and the risk of an ac-
cident is consequently increased.

Starting and operating 7-19
– CONTINUED –
NOTE
In order to prevent over-revving during
deceleration of the vehicle, the trans-
mission will remain in the current gear
if the speed of the vehicle is in excess
of the Maximum Allowable Speed for
the gear to which the selector lever has
been moved.
Driving tips
Always apply the foot or parking brake
when the vehicle is stopped in the “D ”, “3 ”,
“ 2 ”, “1 ” or “R ” position.
Always set the parking brake when parking your vehicle. Do not hold the vehi-
cle with only the transmission.
Do not keep the vehicle in a stationary
position on an uphill grade by using the “ D ”, “3 ”, “2 ”, or “1 ” position. Use the brake
instead.
The engine may, on rare occasions, knock
when the vehicle rapidly accelerates or
rapidly pulls away from a standstill. This
phenomenon is not an indication of a
problem in your vehicle.
Shift lock release
If the selector lever does not move from
the “P ” position with the brake pedal de-
pressed and the ignition switch in the “ON ”
position, perform the following steps:
To override the shift lock:
1. Set the parking brake and stop the en-
gine.
2. Take out the screwdriver from the tool
bag.
3. Remove the cover by prying on the
edge with the screwdriver.
4. Insert the screwdriver into the hole.
5. Push down on the screwdriver and
move the selector lever from the “P ” to the
“ N ” position.
6. Remove the screwdriver from the hole.
Depress the brake pedal and start the en-
When shifting down a gear, ensure
that the vehicle is not travelling at a
speed exceeding the Maximum Al-
lowable Speed for the gear which is
about to be selected. Failure to ob-
serve this precaution can lead to en-
gine over-revving and this in turn
can result in engine damage.
In addition, sudden application of
engine brakes when the vehicle is
travelling on a slippery surface can
lead to wheel locking; as a conse-
quence, control of the vehicle may
be lost and the risk of an accident in-
creased.
700059
700060

7-20 Starting and operating
gine.
Take your vehicle to the nearest SUBARU
dealer immediately to have the system re-
paired.Limited slip differential (LSD)
(if equipped)
The LSD provides optimum distribution of
power according to the difference in revo-
lutions between the right and left wheels
that may be caused by certain driving con-
ditions, thereby improving driving stability
on snow-covered, muddy or other slippery
roads or when high speed driving.
NOTE (WRX-STI)
The rear differential may emit a knock-
ing sound when the vehicle is driven
slowly with the steering wheel turned
fully to either side. This sound occurs
because of the design of the mechani-
cal LSD. It does not indicate a problem.
Never start the engine while a tire
on one side is jacked up, as the
vehicle may move.
If one tire is spinning in mud,
avoid continued spinning at high
speed as this could adversely af-
fect the LSD.
If you use a temporary spare tire
to replace a flat tire, be sure to use
the original temporary spare tire
stored in the vehicle. Using other
sizes will adversely affect the
LSD.

Starting and operating 7-21
– CONTINUED –
Power steering
The power steering system operates only
when the engine is running.
If you lose power steering assist because
the engine stops or the system fails to
function, you can steer but it will take
much more effort.
NOTE
Right after the engine has been started
and before it has warmed up, you may
hear a noise coming from areas adja-
cent to the power steering pump which
is located at the right-front area of the
engine compartment. This noise is nor-
mal. It does not indicate power steering
system trouble.
Braking
Braking tips
When the brakes get wet
When driving in rain or after washing the
vehicle, the brakes may get wet. As a re-
sult, brake stopping distance will be long-
er. To dry the brakes, drive the vehicle at
a safe speed while lightly depressing the
brake pedal to heat up the brakes.
Use of engine braking
Remember to make use of engine braking
in addition to foot braking. When descend-
ing a grade, if only the foot brake is used,
the brakes may start working improperly
because of brake fluid overheating,
caused by overheated brake pads. To
help prevent this, shift into a lower gear to
get stronger engine braking.
Braking when a tire is punctured
Do not depress the brake pedal suddenly when a tire is punctured. This could cause
a loss of control of the vehicle. Keep driv-
ing straight ahead while gradually reduc-
ing speed. Then slowly pull off the road to
a safe place.
Brake system
Two separate circuits
Your vehicle has two separate circuit
brake systems. Each circuit works diago-
nally across the vehicle. If one circuit of
the brake system should fail, the other half
of the system still works. If one circuit fails,
the brake pedal will go down much closer
to the floor than usual and you will need to
press it down much harder. And a much
longer distance will be needed to stop the
vehicle.
Brake booster
The brake booster uses engine manifold
vacuum to assist braking force. Do not
turn off the engine while driving because
that will turn off the brake booster, result-
ing in poor braking power.
The brakes will continue to work even
when the brake booster completely stops
functioning. If this happens, however, you
will have to push the pedal much harder
than normal and the braking distance will
increase.
Do not hold the steering wheel at the
fully locked position left or right for
more than five seconds. This may
damage the power steering pump.
Never rest your foot on the brake
pedal while driving. This can cause
dangerous overheating of the
brakes and needless wear on the
brake pads and linings.

7-22 Starting and operating
Disc brake pad wear warning
indicators
The disc brake pad wear warning indica-
tors on the disc brakes give a warning
noise when the brake pads are worn.
If a squeaking or scraping noise is heard
from the disc brakes while braking, imme-
diately have your vehicle checked by your
SUBARU dealer.
ABS (Anti-lock Brake Sys-
tem)
The ABS system prevents the lock-up of
wheels which may occur during sudden
braking or braking on slippery road surfac-
es. This helps prevent the loss of steering
control and directional stability caused by
wheel lock-up.
When the ABS system is operating, you
may hear a chattering noise or feel a slight
vibration in the brake pedal. This is normal
when the ABS operates.
The ABS system will not operate when the
vehicle speed is below approximately 6
mph (10 km/h).
ABS system self-check
Just after the vehicle is started, you may
feel on the brake pedal a vibration similar
to when the ABS operates, and you may
also hear the sound of the ABS working
from the engine compartment. This is
caused by an automatic functional test of
the ABS system being carried out and
700040
Always use the utmost care in driv-
ing – overconfidence because you
are driving with an ABS equipped
vehicle could easily lead to a seri-
ous accident.
The ABS system does not always
decrease stopping distance. You
should always maintain a safe fol-
lowing distance from other vehi-
cles.
When driving on badly surfaced
roads, gravel roads, icy roads, or
over deep newly fallen snow,
stopping distances may be longer
for a vehicle with the ABS system
than one without. When driving
under these conditions, therefore,
reduce your speed and leave am-
ple distance from other vehicles.
When you feel the ABS system
operating, you should maintain
constant brake pedal pressure.
Do not pump the brake pedal
since doing so may defeat the op-
eration of the ABS system.