2017 AUDI A8 sensor

Audi pre sense
Audi pre sense Preventative passenger
protection
A pp lies to: ve hicles w ith Audi p re se nse
Pre sense can initiate steps to protect vehicle oc­
cupants in certain dangerous situations. The
fu nctions described a re available depending on
ve hicle equi pment:
Audi pre sense basic
The fo llow ing funct ions can be triggered in cer­
tain driving situations:
- Tighten ing of the safety belts (for examp le,
during heavy braking): the front safety belts
have reversible belt tensioners. If a coll is ion
does not occur, the safety belts loosen slightly
and are ready to trigger again.
- Closing the w indows and the sunroof*
The function of the pre sense basic is activated at
a speed of 20 mp h (30 km/h) or higher. The de ­
p loyment time is adapted in the drive select dy­
namic mode.
Audi pre sense front (vehicles with adaptive
cru ise control*)
Pre sense front contains the f unctions of pre
sense basic. In add ition, the likelihood of a rear­
end collis ion with the vehicle ahead is also calcu­
lated, withi n the limits of the system. If the risk
of a collision is detected, the following functions
can t rigge r:
- Audi braking gua rd¢
page 99
- Tensioning of the safety belts
- Closing the windows and the sunroof *
Audi pre sense rear (vehicles with side
a ss ist* )
Pre sense rear contains the functions of p re sense
basic. In addition, the li ke lihood of a rear-end
col lision from the vehicle be hind is a lso ca lculat­
ed, w ith in the lim its of the system .
If the risk of a
collis ion is detected, the following functions can
tr igger:
- Tens ioning of the safety be lts
- Closing the windows and the sunroof *
216
- Adjusting the seats: the settings for the powe r
head restrains, the upper sections of the backr­
ests and the pne umatic side bolsters* change
on the front seats and the outer rear seats*. If
a collision does not occur, the seat sett ings
that were previously used are restored .
Audi pre sen se plus
Pre sense plus contains the f unctions of p re
sense front and pre sense rear.
Error message
Audi pre sense : Unavailable
Preventative passenger protection is not ava ila­
ble. Drive to yo ur autho rized Aud i dea le r o r au­
t h ori zed Aud i Service Facility immedia tely to have
t h e malfunct ion corre cte d.
.&_ WARNING
Pr e sense canno t overcome natura l phys ica l
l aws . It is a system designed to assist and it
cannot prevent a co llision. Do not let t he in­
creased sa fety provided tempt you into tak ing
risks . T his could inc rease your ris k of a colli ­
sion.
- The system can dep loy inco rrectly.
- Please note that the sensors do not always
detect a ll objects. Th is increases the r is k of
a co llision.
- Pre sense does not react to peop le or ani­
mals or objects that a re c rossing the vehi­
cle's path or are difficu lt to detect
¢page 94.
- Ref lective objects such as gua rd ra ils o r the
entrance to a tunne l, heavy rain and ice can
affect the funct io n of the radar sensors a nd
t he system 's ability to de tect a collision risk.
(D Note
The sensors can be d isplaced by impacts or
damage to the bumper , wheel housing a nd
underbody . Pre sense can be impaired by this .
Have an autho rized Aud i deale r or autho rized
A udi Service Fac ility ch eck their f unct io n. .,..

Safety belt s
A WARNING
Always read and heed all WARNINGS and oth­
er important informat ion
c:> page 220 .
(D Tips
You can also adjust the height of the front
seats to change the position of the safety
belts.
Improperly worn safety belts
Incorrectly posit ioned safety belts can cause se­
vere injuries.
Wearing safety belts imprope rly can cause seri­
ous injury or death. Safety belts can on ly work
when they a re correctly positioned on the body.
Improper seating positions reduce the effect ive­
ness of safety belts and wi ll even increase the
ris k of injury and deat h by mov ing the safety bel t
to cr it ica l areas of the body . Imp roper seating
posi tions a lso increase the risk of serio us in jury
an d deat h when an air bag deploys and strikes an
oc cupan t who is no t in the co rrect seating pos i­
tion. A d river is responsib le for the safety of a ll
ve hicle occupants and especia lly for children.
Therefo re:
... Neve r permit anyone to ass ume an in co rrect
s itting position in the vehicle w hil e trave ling
c:> & .
A WARNING
Improperly worn safety belts increase t he risk
of se rious personal injury and deat h wheneve r
a vehicle is being used.
- Always make sure that all vehicle occupants
are correctly restra ined and stay in a correct
seat ing pos ition whenever the veh icle is be­
ing used.
- Always read a nd heed all WARNINGS and
othe r important information
c:> pag e 220.
224
Belt tensioners
' How safety belt pretensioners work
In front, side and rear-end collisions above a
particular sev erity and in a rollover, safety b elts
are tensioned automatically.
Rever sible safety belt tensioners
The safety belts on the front seats a re equipped
with power revers ible tensione rs. The following
funct ions are available whe n the drive r's/front
passenger 's safety belts are faste ned:
- Automatic tens ione rs: at the start of a drive,
the safety belts automat ically adjust to t he
passe nger after a certain time period or ve hicle
speed. To switch t he automatic tensioners off,
select the follow ing in the MMI :
!CARI fu nction
but to n
> Car systems > Vehicle setting s >
Seats > Driver's seat or Passenger's seat > Au­
tomatic belt tensioner
> Off .
-In ce rta in dr iving situ ations , the safe ty belts
may tighten w ith a reve rsib le tensioning func ­
t ion
c:> page 216 .
- Th e safety be lts may also tighten with this re -
vers ible te nsion ing f un ct ion in m ino r collisions.
Pyrotechnic safety belt pretensioners
The safety belts are eq uipped w ith safety bel t
p retens ione rs . The system is activa ted by sensors
i n front, side a nd rear-e nd coll is ions of grea t se­
verity and in a ro llover. This tig htens the bel t and
t ak es up belt sla ck
c:> .&. in Service an d disposal of
safety belt pretensioner on page 225.
Taking up
the slack he lps to reduce forward occupant
movement during a collision.
A WARNING
- It is poss ible for the pretensioners to dep loy
incor rect ly.
- The pyrotechnic system can only p rovide
protection for one collision. If t he py rotech­
nic pretens io ners deploy, the pretensioning
sys tem must be replaced .
(1) Tips
The pyrotechnic sa fety belt pretensioners can
on ly dep loy once . ..,_

Airbag syste m
-a small adu lt or teenager is on the front pas ­
senger seat
- a passenger who is not sitting upright with
their back against a non -reclined backrest with
their feet on the vehicle floor in front of the
seat is on the front passenger seat.
I f the front passenger airbag dep loys, the Feder ­
al Standard requires the airbag to meet the "low
risk" deployment criteria to help reduce the risk
of injury through interaction with the airbag.
"Low risk" deployment occurs in those crashes
that take place at lower decelerations as def ined
in the electronic control unit¢
page 236.
Alway s remember: Even though your vehicle is
equ ipped w ith Advanced Airbags, the safest place
for children is properly restrained on the back
seat . Please be sure to read the important infor­
mat ion in the sections that follow and be sure to
heed a ll of the WARN INGS.
A WARNING
To red uce the risk of inj ury when an ai rbag in­
fla tes, a lways wear safety bel ts p roperly.
- If you are unrestrained, leaning fo rwa rd, s it­
t ing s ideways or o ut of pos ition in any way,
yo ur risk of in jury is much h igher .
- Yo u will also re ceive serious injur ies and
could even be killed if you are up aga inst the
airbag or too close to it when it inflates -
even with an Advanced Airbag ¢
page 226.
A WARNING
A child in a rearward-facing chi ld seat insta l­
led on the front passenger seat will be seri­
ously injured and can be k illed if the front air­
bag inflates -even with an Advanced Airbag
System.
- Although the Advanced A irbag System in
your vehicle is designed to turn off the front
airbag when a rearward-facing child re­
straint has been installed on the front pas­
senger seat, nobody can absolutely g uaran­
tee that deployment is impossible in all con­
ceivable s ituations that may happen during
the usef ul life of your vehicle .
- The inflating a irbag w il l hit the child seat or
infant carrier w ith great force and will
232
-
smash the child seat and child against the
backrest, center armrest, door, or roof.
- Always install rearward-facing child re ­
straints on the rear seat.
- If you must install a rearward facing child
seat on the front passenge r seat because of
except ional circumstances and the
PASSEN­
GER AIR BAG OFF
light does not come on
and stay on, immed iate ly install the rear­
facing chi ld seat in a rear seating posit ion
and have the airbag system inspected by
your Aud i dea le r.
A WARNING
If, in exceptional ci rcums tances, you must in­
stall a forward-facing child restraint on the
fron t passenger's seat:
- Always make sure the forward-fa cing sea t
has been des igned and certified by its man­
ufacturer for use on a front seat with a pas ­
senger front and side airbag.
- Never put the forwa rd-facing child restrain t
up against or very near the instr ument pan ­
el.
-Always move the front passenge r seat to
the highest position in the up and down ad­
justment range and move it back to the
rearmost position in the seat's fore and aft
ad justment range, as far away from the air­
bag as poss ible, before installing the for­
ward-facing chi ld restraint.
- Always make sure that the safety be lt upper
anchorage is behind the ch ild restraint and
not next to or in fron t of the child restraint
so that the safety be lt will be p roperly posi­
tioned.
- Ma ke sure that the
PASSENGER AIR BAG
OFF
li ght comes on and stays on a ll the time
wheneve r the ign it ion is swi tched on.
· Advanced Airbag System components
The fro nt passenge r sea t in your veh icle has a lo t
of ve ry important parts o f the Advanced A irbag
System in it. These parts include t he weight­
sensing mat, sensors, wiring, brackets, and
more. The fu nction of the system in the front
passenger seat is checked by the electronic
1111>

control unit when the ignition is on. The control
unit monitors the Advanced Airbag System and
turns the airbag indicator light on when a ma l­
function in the system components is detected. The funct ion of the a irbag indicator light is de­
scr ibed in greater deta il below . Because the front
passenger seat contains important parts of the
Advanced Airbag System, you must take care to p revent it from being damaged. Damage to the
seat may preven t the Advanced A irbag for the
fron t passenger seat from doing its job in a
crash .
The front Advanced Airbag System consists
of the follo wing :
-Crash sensors in the front of the vehicle that
measure vehicle acceleration/deceleration to
provide information to the Advanced Airbag
System a bout the severity of the crash.
- An e lectronic control unit, with integrated
crash sensors for front and side impacts. The
control unit "decides" whether to fire the front
airbags based on the information received from
the crash sensors. The control unit also "de­
c ides" whether the safety belt pretens ioners
should be activated .
- An Advanced Airbag with gas generator and
control valve for the driver ins ide the steer ing
wheel hub .
- An Advanced Airbag with gas generator and control valve inside the instrument pa nel for
the front passenger.
- A weig ht-sensing mat under the upholstery
padd ing of the front passenger seat cushion
that meas ures the total weight on the seat. The
i nformation registered is sent continuously to
the e lectron ic cont rol unit to reg ulate dep loy­
ment of the front Adv a need Airbag on the pas­
senger side .
- An airbag monitoring system and indicator
light in the instrument cluster
¢ page 236.
-A sensor in eac h front seat registers the dis­
tance between the respective seat and the steering wheel or instrument pane l. The infor­
mation registered is sent contin uously to the
0 co electronic control unit to regulate deployment ....
~ of the front Adva need A irbags. N .... 0 0 :c ' Airb ag sys tem
- The PASSENGER AIR BAG OFF light comes on
and stays on in the center of the instrument
pane l¢
page 237, fig . 233 and te lls yo u when
the front Advanced Airbag on the passenger side has been turned off.
- A sensor below the safety be lt latch for the
front seat passenger to measure the tension on the safety belt. The tension on the safety belt
and the we ight registered by the weight -sens­
ing mat help the contro l unit "decide" whether
the front airbag fo r the front passenger seat
should be tu rned off o r not ¢
page 22 7, Child
restraints on the front seat -some important
things to know.
- A sensor in the safety belt latch for the driver
and for the front seat passenger that senses
whether that safety be lt is latched o r not and
transmits this information to the electronic control unit.
A WARNING ,-
Damage to the front passenger seat can pre-
vent the front airbag from working properly.
- Improper repair or disassembly of the front passenger and driver seat will prevent the
Advanced Airbag System from funct ion ing
properly .
- Repairs to the front passenger seat must be
performed by qualified and properly trained
workshop personnel.
- Never remove the front passenger or driver
seat from the vehicle.
- Never remove the upholstery from the front
passenger seat.
- Never d isassemble or remove parts from the
seat or disconnect w ires from it.
- Never carry sharp objects in your pockets or
p lace them on the seat. If the weight-sens­
ing mat in the passenger seat is punctured
it cannot work properly .
- Never carry things on your lap or carry ob­
jects on the passenger seat . Such items can
increase the weight reg istered by the
weight-sensing mat and send the wrong in­
formation to the a irbag con trol u nit.
- Never store items under the front passenger
seat. Parts of the Advanced Airbag System
under the passenger seat cou ld be
~
233

Airbag syste m
damaged, preventing them and the airbag
system from working properly.
- Never place seat covers or rep lacement up­
holstery that have not been specifically ap­
proved by Audi on the front seats .
- Seat covers can prevent the Advanced Air­
bag System from recognizing child re­
straints or occupants on the front passenger
seat and prevent the side a irbag in the seat
backrest from deploying properly.
- Never use cush ions, pillows, blankets or
similar items on the front passenger seat.
The add it ional padding will prevent the
weight-sens ing mat in the seat from acc u­
rately reg istering the ch ild restraint or per­
son on the seat and prevent the Advanced
Airbag System from funct ioning properly.
- If you must use a child rest raint on the front
passenge r seat and the child restraint man­
ufacturer 's instructions require the use of a
towel, foam cushion or something else to properly position the ch ild restraint, make
certain that the
PA SSENGER AIR BAG OFF
light comes on and stays on whenever the
child restraint is installed on the front pas­
senger seat.
- If the
PASSEN GER AIR B AG OFF light does
not come on and stay on, immed iately in­
stall child restraint in a rear seating position and have the airbag system inspected by
yo ur Audi dealer.
How the Advanced Airbag System
components work together
The front Advanced Airbag System and the side
airbags supplement the protection offered by the
front three-po int safety belts with pretensioners
and load limiters and the adjustable head re­
stra ints to help reduce the r isk of injury in a wide
range of accident and crash situations. Be sure to read the important informa tion about safety and
heed the WARN INGS in t his chapter.
Deployment of the Advanced Airbag System and
the act ivat ion of the safety belt pretensioners de­
pend on the deceleration measu red by the crash
sensors and regis tered by the electronic control
unit. Crash severity depends on speed and decel-
2 34
eration as well as the mass and stiffness of the
vehicle or object involved in the crash .
On the passenger side, regard less of safety be lt
u se, the airbag will be turned off if the weight on
the passenger seat is less than the amount pro­
grammed in the electronic control unit . The front
airbag on the passenger side will also be turned
off if one of the child seats that has been certi­
fied under Federal Motor Vehicle Safety Standard 208 has been recognized on the seat. The
PA S­
S ENGER AIR BAG OFF
light comes on and stays
on to tell you when the front Advanced A irbag on
the passenger side has been turned off
q page 22 7, Child restraints on the front seat­
some important things to know.
A WARNING
To reduce the ris k of injury when an airbag in ­
f lates, always wea r safety belts properly.
- If you are un restrained, leaning forward, sit ­
ting sideways or out of position i n any way,
your risk of injury is much higher.
- You will a lso receive serious injuries and
could even be killed if you are up against the
airbag or too close to it when it inflates -
even with an Advanced Airbag
q page 226.
More important things to know about front
airbags
Fig . 232 Inflated front a irbags
Safety be lts are important to help keep front
seat occupants in the proper seated position so
that airbags can unfold properly and prov ide sup-
plemental protection in a fronta l collision . ..,.

Airbag syste m
-Ne ver t ransport items on or in the area of
t h e fr ont passenger seat. Objects could
m ove into the area of the front airbags dur­
ing brak ing or oth er sudden maneuvers and
become dangerous projectiles that can
cause serious pe rsonal injury if the a irbags
inflate.
- Never place or attach accessor ies or other
objects (such as cup holders, te lephone
brackets, large, heavy o r bulky objects) on
the doors, over or ne ar the area marked
"AIRBAG" on the steering wheel, instru ­
ment pane l, seat bac krests or between
t h ose areas and yourself. These objects
could cause injury in a crash, especially
when the airbags inflate.
- Never recline the front passenge r's seat to
transport objects. Items can also move into
the area of the side airbag o r the front a ir­
bag dur ing braking or in a s udden maneu­
ver. Objects near the airbags can become
projectiles and cause in ju ry, particularly
when the sea t is re clin ed.
.8, WARNING
The f ine dust create d when airbags deploy can
cause breathing problems for people w ith a
his tory of asthma or o ther breathing condi­
tions .
- T o reduce the risk o f brea thing pro blems,
those w ith asthma or o ther respiratory con ­
ditions should get fresh air right away by
gett ing out of the vehicle o r opening w in­
dows o r doors.
- If you are in a collision in which airbags de­
ploy, wash your hands and face with mild
soap and water before eat ing.
- Be careful not to get the dust into your eyes,
or into any cuts or scratches.
- If the resid ue should get into your eyes,
flush them with water.
236
Monitoring the
Advanced Airbag System
tli (USA models )/!{' (Canada model s)
Airbag monitoring indicator light
Two separate indicators monitor the function of
the Advanced Airbag System: the airbag moni­
toring indicator light and the
PASSENGER AIR
BAG OFF
light.
The Advanced A irbag System ( including the e lec ­
tronic control unit, sensor circuits and system
wiring) is monitored continuously to make sure
that it is functioning properly whenever the igni­
tion is o n. Each time you sw itch on the ig nition,
the a irbag mo nitor ing indica to r light
II (U SA
models)/ fll (Canada models) w ill come o n for a
few seconds (se lf d iagnost ic s) .
The system must be inspected when the
indicator light
fl (USA models) /E,I (Canada
models) :
-does not come on when the igni tion is sw itched
on,
- does not go out a few se co nd s afte r you h ave
sw itched on the ignit ion, or
- comes on while driv ing.
If an airbag system malfunction is detected, the
i ndica to r light will come on to se rve as a constant
r em inder to have t he system inspected immedi­
ate ly.
If a ma lfunction occurs that turns the front air­
bag on the passenge r side off, the
PASSENGER
A IR BAG OFF
light w ill come on and stay o n
whe never the ignition is on.
_& WARNING
A n a ir b ag system t hat i s no t functioning prop­
e rly cannot provide sup plemental pro te ct ion
in a fronta l crash .
- If the air bag ind icator ligh t<=? page 23
comes when the vehicle i s being u sed, have
the system inspected immediately by your
author ized Audi dealer . It is possib le that
the airbag will inflate when it is not sup­ posed to, or will not inflate when it should.

0 co .... N ,..... N .... 0 0 :c - PASSENGER AIR BAG OFF light
Fig. 233 Section from the instrument panel: PASSENGER
AIR BAG O FF light
The PA SSENGER AIR BAG OFF light is located in
the center o f the instrument panel¢
fig. 233 .
The PASSENGER AIR BAG OFF light will come on
and stay on to tell you when the front Advanced
Ai rbag on the passenger side has been turned off
by the electronic control unit . Each time you
switch on the ignition, the
PAS SENGER AIR BAG
O FF
light will flash for a few seconds and :
- will stay on if the front passenger seat is not
occupied,
- will stay on if there is a small ch ild or chi ld re­
straint on the front passenger seat,
- will go out if the fro nt passenge r seat is occu­
pied by an adul t as reg istered by the weight­
sensing mat .
The
PASSENGER AIR BAG OFF light m ust c ome
on and st a y on
if the ignition is on and
- a car bed has been installed on the front seat, or
- a rearward-facing child restraint has been in­
stalled on the front passenger seat, or
- a forward-facing child restra int has been instal­
led on the front passenger seat, or
- the weight reg istered on the front passenger
seat is equal to or less than the combined
we ight of a typical 1 year -old restrained in one
of the rear-facing or forward-fac ing infant re­
straints listed in Federal Motor Vehicle Safety
Standard 208 w ith w hich the Advanced A irbag
System in your ve hicle was certified .
I f the front passenger seat is not occupied, the
front a irbag w ill not deploy, and the
PASSENGER
Airb ag sys tem
AIR BAG OFF light wi ll stay on . Never insta ll a
rearward -facing child restraint on the front pas­
senger seat, the safest place for a chi ld in any
k ind of child restraint is at one of the seating po ­
s itions on the rear seat¢
page 22 7, Child re­
straints on the front seat -some important
things to know
and ¢ page 248, Child safety.
If the PA SSENGER AIR BAG OF F light come s on
when one of the conditions listed above is met,
be sure to check the light regularly to make cer ­
ta in that the
PA SSENGER AIR BAG OFF light
stays on continuously whenever the ignition is
o n . If the
PA SSENGER AIR BAG OFF light does
not appea r on and does no t stay on all the time ,
stop as soon as it is safe to do so and
- reactivate the system by sw itching the ign ition
off and then switching it on aga in ;
- remove and re install the child restraint . Make
sure that the child restra int is properly insta l­
led and tha t the safety belt for the front pas­
senger seat h as bee n correct ly routed th rough
the child restraint as desc ribed in the chi ld re ­
straint manufacturer's instructions;
- make sure that the convert ible lock ing retrac­
to r on the safety belt for the fro nt passenge r
seat has been activated and that the safety belt
has been pulled tight. The belt m ust not be
loose or have loops of slack so that the sensor
be low the safety belt latch on the seat can do
its job ¢
page 258 .
-make su re that th ings that may increase the
weight of the child and ch ild seat are not being
transported o n the front passenge r seat;
- make su re that the safety be lt tens ion sensor is
not blocked. Shake the safety belt latch on the
front passenger seatback and forth;
- If a strap or tether is being used to tie the child
seat to the front passenger seat, make su re
that it is not so tight that it causes the weight­
sensi ng mat to measure more weight than is
act ually on the seat.
If th e PA SS ENGER AIR BA G OFF light still does
not come on
and does not stay on co ntinuously
(whe n the ign ition is sw itc hed on),
- take the child restra int off the front passenger
seat and install it properly at one of the rear ..,_
237

Airbag syste m
service action is entered in your Audi War­
ranty
& Maintenance book let under AIRBAG
REPLACEMENT RECORD.
- For safety reasons in severe accidents, the
alternator and starter are separated from
the vehicle battery with a pyrotechnic circuit interrupter.
- Work on the pyrotechnic circuit interrupt­
er must only be performed by a qualified
dea ler· risk of an accident!
- If the veh icle or the circuit interrupter is
scrapped, all applicab le safety precautions
must be followed .
@ For the sake of the environment
Undeployed airbag modu les and pretension ­
ers might be classified as Perch lorate Materi­
al -special handling may apply, see
www .dtsc.ca.gov/hazardouswaste/perchlo­
rate. When the vehicle or parts of the re­
straint system including airbag modules and
safety belts w ith pretensioners are scrapped,
all applicable laws and regulations must be
observed. Your authorized Audi dealer is fa­
m iliar with these requirements and we recom­
mend that you have your dealer perform this
serv ice for you .
Other things that can affect Advanced
Airbag performance
Changing the vehicle's suspension system can
change the way that the Advanced Airbag System
performs in a crash. For example, using t ire-r im
comb inat ions not approved by Audi, lower ing the
veh icle, chang ing the st iffness of the suspens ion,
including the springs, suspension struts, shock
absorbers etc. can change the forces that are
measured by the airbag senso rs and sent to the
electronic contro l unit. Some suspension changes
can, for example, increase the force levels meas­
ured by the sensors and make the airbag system
deploy in crashes in which it would not deploy if
the changes had not been made. Other kinds of changes may reduce the force levels meas ured by
the sensors and prevent the airbag from deploy­ ing when it should .
240
A WARNING
Changing the vehicle's suspension including
use of unapproved tire-rim comb inations can
change Advanced Airbag performance and in­
crease the r isk of serious personal injury in a
crash.
- Never insta ll suspension components that
do not have the same performance charac­
ter istics as the components origina lly ins tal­
led on you r vehicle.
- N ever use tire-r im combinations that have
no t been approved by Aud i.
A WARNING
It ems stored between the safety belt buckle
and the center conso le can cause the sensors
in the buckle to send the wrong information
to the electronic contro l module and prevent
the Advanced A irbag System from working
proper ly.
- Always make sure that nothing can interfere
with the safety belt buckles and that they
are not obstructed.
Knee airbags
Description of knee airbags
The knee airbag system can provide supplemen­
tal protection to properly restrained front seat
occupants.
Fig . 234 D river 's knee a irbag
The driver knee airbag is in the instrument panel
underneath the steering wheel~
fig. 234, the
airbag for the passenger is at about the same height in the instrument panel underneath the
glove compartment . ..,_