SUBARU IMPREZA WRX 2012 4.G Owners Manual

7-18Starting and operating
Driver ’s Control Center Dif-
ferential (DCCD) (STI)
WARNING
Always use the utmost care when
driving. Being overconfident be-
cause you are driving a vehicle with
a driver ’s control center differential
could easily lead to a serious acci-dent.
CAUTION
All the indicator lights will flash in
the event that the driver ’s control
center differential has a malfunc-
tion. Have the vehicle inspected by
your SUBARU dealer.
The driver ’s control center differential
allows you to freely change the degree
of limitation of the differential action
(limited slip differential (LSD) torque) of
your vehicle ’s center differential.
By using the center differential control
switch, 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
3) Initial LSD torque (maximum)
4) Initial LSD torque (minimum)
A) Initial LSD torque (adjustable)
B) Mechanical LSD torque
The driver ’s control center differential has
an auto mode and a manual mode. In the
auto mode, the system automatically
adjusts the initial LSD torque. In the
manual mode, you can change to the
desired mode manually by using the
center differential control switch.
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
occurs because of the structure of the
center differential. It does not indicate aproblem. &
To change mode of driver ’s
control center differential
Press the “AUTO-MANU ”switch on the
center console to switch from auto mode
to manual mode or vice versa. When you
select the auto mode, the “AUTO ”indica-
tor light illuminates. When you select the
manual mode, the “AUTO ”indicator light
turns off.

&Auto mode
In the auto mode, the system estimates
the driving and road conditions using
signals from the wheel speed sensor,
throttle position sensor, steering angle
sensor and brake switch, etc. According
to the result, it electronically and auto-
matically controls the degree of limitation
of the differential action (LSD torque) to
optimize the differential action of the
center differential. When the ignition
switch is turned ON, the “AUTO ”indicator
light on the combination meter illuminates. The auto mode has 3 modes as follows.
Mode Operation
AUTO [+] This mode emphasizes traction control and strengthens the
limitation of differential action
that is suitable for driving on
slippery roads for vehicle stabi-
lity.
AUTO This mode is suitable for most driving situations.
AUTO [ ] This mode is suitable when you
seek quick response from the
steering wheel and smooth driving.
! Mode setting method
In most situations, it is recommended that the “AUTO ”mode is selected.
Push the control switch forward to select the
“AUTO [+] ”mode. After setting the
mode, “
”on the combination meter
illuminates.
Pull the control switch rearward to select the “AUTO [ ]” mode. After setting the
mode, “
”on the combination meter
illuminates.
When the “AUTO [+] ”mode is selected,
pull the control switch rearward to change
to the “AUTO ”mode. When the “AUTO
[ ]” mode is set, push the control switch
forward to change to the “AUTO ”mode.
Starting and operating
7-19
– CONTINUED –

7-20Starting and operating
& Manual mode
In the manual mode, you can use the
center differential control switch to adjust
the initial LSD torque as desired. When
this mode is selected, the “AUTO ”indica-
tor light on the combination meter turns
off. !
Center differential control switch
and indicator lightThe control switch is located beside the
parking brake lever. By pushing the
control switch forward or pulling it rear-
ward, it is possible to change the initial
LSD torque.
The center differential indicator lights on
the combination meter give six levels of
indication. The indicator lights and control
switch are linked; when the switch is
pushed or pulled to change the initial
LSD torque, the illumination position of the
indicator lights changes accordingly.
Push the switch forward to increase the
initial LSD torque; when the “LOCK ”
indicator light illuminates, the initial LSD
torque setting is maximum. The center
differential will then be almost completelylocked.

Pull the switch rearward to reduce the
initial LSD torque. When the lowest posi-
tion of the driver’s control center differen-
tial indicator light illuminates, the initial
LSD torque will be minimum. Under this
condition, only the Mechanical LSD torque
will limit the differential action.
CAUTION
. Do not operate the control switch
when a wheel slippage occurs.
Wait until the wheelspin has been
brought under control.
. Under any of the following con-
ditions after setting to the man-
ual mode, pull the center differ-
ential control switch 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 se-lected
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. When the vehicle is stuck
in snow or mud, setting the initial LSD
torque to the maximum will help to free
the vehicle.. The setting of the initial LSD torque
will remain even when the auto mode is
selected or the ignition switch is turned
to the “LOCK ”position. However, the
initial LSD torque will be minimized
when the battery is disconnected andreconnected.. During cornering or when making
turns (especially when going 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
indicate a problem. The phenomenon
will disappear when setting the initial
LSD torque to the minimum.
In the auto mode, it controls the initial
LSD torque automatically. While in the
auto mode, this phenomenon some-
times occurs depending on the driving
condition, however, it does not indicate
a problem..
Use the center differential indicator
light only as a rough indication of the
initial LSD torque.. If you operate the center differential
control switch while quickly accelerat-
ing or turning a tight corner, you may
feel slight shocks. This is due to
differential action by the center differ-
ential and does not indicate a problem. & Temporary release
When the driver stops the vehicle and
pulls the parking brake lever after manu-
ally setting the initial LSD torque, the LSD
torque is temporarily minimized. However
the indicator on the combination meter
continues to show the driver ’s selected
initial LSD torque. When the driver re-
leases the parking brake lever, the initial
LSD torque set by the driver is restored. Starting and operating
7-21

7-22Starting and operating
SI-DRIVE (STI)
SI-DRIVE (SUBARU Intelligent Drive)
works to maximize engine performance,
control and efficiency.
This system consists of three modes:
Intelligent (I), Sport (S), and Sport Sharp
(S#). By adjusting the SI-DRIVE selector,
the character of the power unit changes. &Intelligent (I) mode
! For smooth, efficient performance driving
The Intelligent (I) mode provides well-
balanced performance with greater fuel
efficiency and smooth driveability without
stress. Power delivery is moderate during
acceleration for maximum fuel efficiency. This is ideal for around-town driving and
situations that do not require full power
output. It provides better control in difficult
driving conditions, such as slippery roads
or loose surfaces, due to gentler throttleresponse.
When Intelligent (I) mode is selected, a
shift-up indicator
“”on the combination
meter will blink to signal the best time to
shift gears for maximum fuel efficiency. &
Sport (S) mode
! For all-around performance driving
The Sport (S) mode provides the engine
power desired by those who want to make
the driving experience their own personaladventure.
The linear acceleration characteristic of
this versatile mode is ideal for normal
driving use.

&Sport Sharp (S#) mode
! For maximum performance driving
For sports-minded drivers, the Sport
Sharp (S#) mode offers an exhilarating
level of engine performance and control.
The throttle becomes more responsive
regardless of the engine speed. Delivering
maximum driving enjoyment, this mode is
ideal for tackling twisting roads and for
merging or overtaking other vehicles on
the freeway with confidence. &
SI-DRIVE selector
When you rotate the SI-DRIVE selector to
the left, the current SI-DRIVE mode
changes to Sport (S) mode. When you
rotate it to the right, the mode changes to
Sport Sharp (S#) mode, and when you
push it, the mode changes to Intelligent (I)
mode. After performing this operation, the
switch returns to its original location.
NOTE . The next time you turn on the
engine, after you turned off the engine
in the Sport Sharp (S#) mode, the SI-
DRIVE mode changes to the Sport (S)mode.. The next time you turn on the
engine, after you turned off the engine
in the Sport (S) mode or Intelligent (I)
mode, the SI-DRIVE mode will stay in the same mode as when the engine
was turned off..
While the engine is running, if the
CHECK ENGINE warning light/malfunc-
tion indicator light illuminates, the SI-
DRIVE mode changes to the Sport (S)
mode. In this case, it is not possible to
change to the Sport Sharp (S#) mode or
Intelligent (I) mode.. If there is a possibility that the
engine could overheat because of a
temperature increase of the engine
coolant, it is not possible to change to
the Sport Sharp (S#) mode. While the
vehicle is in the Sport Sharp (S#) mode,
it changes to the Sport (S) mode when
the engine coolant temperature in- creases.. If any of the SI-DRIVE indicators
blink, the SI-DRIVE system may be
malfunctioning. Contact your SUBARU
dealer. Starting and operating
7-23

7-24Starting and operating
Limited slip differential (LSD) (STI)
The LSD provides optimum distribution of
power according to the difference in
revolutions between the right and left
wheels that may be caused by certain
driving conditions, thereby improving driv-
ing stability on snow-covered, muddy or
other slippery roads or when high speeddriving.
CAUTION
. 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
affect 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. 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.
CAUTION
Do not hold the steering wheel at the
fully locked position left or right for
more than 5 seconds. This may
damage the power steering pump.
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
normal. It does not indicate power
steering system trouble. Braking &
Braking tips
WARNING
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.
! When the brakes get wet
When driving in rain or after washing the
vehicle, the brakes may get wet. As a
result, brake stopping distance will be
longer. 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
driving straight ahead while gradually
reducing 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 diag-
onally 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 thevehicle. ! 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 depress the pedal much
harder than normal and the braking dis-
tance will increase. !
Brake assist system
WARNING
Do not be overconfident about the
brake assist. It is not a system that
brings more braking ability to the
vehicle beyond its braking capabil-
ity. Always use the utmost care
when driving regarding vehicle
speed and safe distance.
CAUTION
When you need to brake suddenly,
continue depressing the brake pedal
strongly to bring the effect of the
brake assist.
Brake assist is a driver assistance system.
It assists the brake power when the driver
cannot depress the brake pedal strongly
and the brake power is insufficient.
Brake assist generates the brake power
according to the speed at which the driver
depresses the brake pedal. NOTE
When you depress the brake pedal
strongly or suddenly, the following
phenomena occur. However, even
though these occur, they do not indi- cate any malfunctions, and the brake
assist system is operating properly. .
You might feel that the brake pedal
is applied by lighter force and gener-
ates a greater braking force.. You might hear the sound of ABS
operating from the engine compart-ment. & 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, im-
mediately have your vehicle checked by
your SUBARU dealer. Starting and operating
7-25

7-26Starting and operating
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 sur-
faces. 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).
WARNING
Always use the utmost care in driving –overconfidence because
youaredrivingwithanABS
equipped vehicle could easily lead
to a serious accident.
CAUTION
. The ABS system does not always
decrease stopping distance. You
should always maintain a safe
following distance from other vehicles.
. When driving on badly surfaced
roads, gravel roads, icy roads, or
over deep newly fallen snow,
stopping distances may be long-
er for a vehicle with the ABS
system than one without. When
driving under these conditions,
therefore, reduce your speed and
leave ample distance from othervehicles.
. 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
operation of the ABS system.
& 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
does not indicate any abnormal condition. & ABS warning light
Refer to “ABS warning light ”F 3-18. Electronic Brake Force Dis-
tribution (EBD) system
The EBD system maximizes the effective-
ness of the brakes by allowing the rear
brakes to supply a greater proportion of
the braking force. It functions by adjusting
the distribution of braking force to the rear
wheels in accordance with the vehicle
’s
loading condition and speed.
The EBD system is an integral part of the
ABS system and uses some of the ABSsystem ’s components to perform its func-
tion of optimizing the distribution of brak-
ing force. If any of the ABS components
used by the EBD system malfunction, the
EBD system also stops working.
When the EBD system is operating, you
may hear a chattering noise or feel a slight
vibration in the brake pedal. This is normal
and does not indicate a malfunction.

&Steps to take if EBD system malfunctions
If a malfunction occurs in the EBD system,
the system stops working and the brake
system warning light and ABS warning
light illuminate simultaneously.
The EBD system may be malfunctioning if
the brake system warning light and ABS
warning light illuminate simultaneously
during driving.
Even if the EBD system malfunctions, the
conventional braking system will still func-
tion. However, the rear wheels will be
more prone to locking when the brakes
are applied harder than usual and thevehicle ’s motion may therefore become
somewhat harder to control.
If the brake system warning light and ABS warning light illuminate simultaneously,
take the following steps.
1. Stop the vehicle in the nearest safe,
flat location.
2. Shut down the engine, apply the
parking brake, and then restart it.
3. Release the parking brake. If both
warning lights turn off, the EBD system
may be malfunctioning. Drive carefully to
the nearest SUBARU dealer and have the
system inspected.
4. If both warning lights illuminate again
and remain illuminated after the engine
has been restarted, shut down the engine
again, apply the parking brake, and check
the brake fluid level. Refer to
“Brake fluid ”
F 11-18.
5. If the brake fluid level is not below the“ MIN ”mark, the EBD system may be
malfunctioning. Drive carefully to the
nearest SUBARU dealer and have the
system inspected.
6. If the brake fluid level is below the “ MIN ”mark, DO NOT drive the vehicle.
Instead, have the vehicle towed to the
nearest SUBARU dealer for repair.
WARNING
. Driving with the brake system
warning light illuminated is dan- gerous. This indicates your brake
system may not be working
properly. If the light remains
illuminated, have the brakes in-
spected by a SUBARU dealer
immediately.
. If at all in doubt about whether
the brakes are operating prop-
erly, do not drive the vehicle.
Have your vehicle towed to the
nearest SUBARU dealer for re-
pair. Starting and operating
7-27