1999 TOYOTA SIENNA sensor

name. SIENNA (45403U)
64
CAUTION
After inserting the tab, make sure
the tab and buckle are locked and
that the seat belt extender is not
twisted.
Do not insert coins, clips, etc. in
the buckle as this may prevent you
from properly latching the tab and
buckle.
If the seat belt does not function
normally, immediately contact your
Toyota dealer. Do not use the seat
until the seat belt is fixed. It cannot
protect an adult occupant or your
child from injury.
—Front seat belt pretensioners
The driver and front passenger ’s seat
belt pretensioners are designed to be
activated in response to a severe fron-
tal impact.
When the airbag sensor detects the shock
of a severe frontal impact, the front seat
belt is quickly drawn back in by the re-
tractor so that the belt snugly restrains
the front seat occupants.
The seat belt pretensioners are activated
even with no passenger in the front seat.This indicator comes on when the igni-
tion key is turned to the ”ACC” or
”ON” position. It goes off after about
6 seconds. This means the front seat
belt pretensioners are operating proper-
ly.
This warning light system monitors airbag
sensor assembly, seat belt pretensioner
assembly, warning light, interconnecting
wiring and power sources. (For details,
see ”Service remainder indicators and
warning buzzers” in Chapter 1−5.)
ProCarManuals.com

name. SIENNA (45403U)
65
The seat belt pretensioner system mainly
consists of the following components and
their locations are shown in the illustra-
tion.
1. Front airbag sensors
2. SRS airbag warning light
3. Seat belt pretensioner assemblies
4. Airbag sensor assembly
The seat belt pretensioner is controlled by
the airbag sensor assembly. The airbag
sensor assembly consists of a safing sen-
sor and airbag sensor.When a seat belt pretensioner is acti-
vated, an operating noise may be heard
and a small amount of smoke−like gas
may be released. This gas is harmless
and does not indicate that a fire is occur-
ring.
Once the seat belt pretensioner has been
activated, the seat belt retractor remains
locked.
CAUTION
Do not modify, remove, strike or open
the front seat belt pretensioner as-
semblies, airbag sensor or surround-
ing area or wiring. Doing any of
these may cause sudden operation of
the front seat belt pretensioners or
disable the system, which could re-
sult in death or serious personal inju-
ry.
Failure to follow these instructions
can result in death or serious inju-
ries.
NOTICE
Do not perform any of the following
changes without consulting your
Toyota dealer. Such changes can
interfere with proper operation of the
seat belt pretensioners in some
cases.
Installation of electronic items such
as a mobile two−way radio, cassette
tape player or compact disc player
Repairs on or near the front seat
belt pretensioner assemblies
Modification of the suspension sys-
tem
Modification of the front end struc-
ture
Attachment of a grille guard (bull
bar, kangaroo bar, etc.), snowplow,
winches or any other equipment to
the front end
Repairs made on or near the front
fenders, front end structure or con-
sole
ProCarManuals.com

name. SIENNA (45403U)
67
CAUTION
A driver or front passenger too close
to the steering wheel or dashboard
during airbag deployment can be
killed or seriously injured. Toyota
strongly recommends that:
The driver sit as far back as pos-
sible from the steering wheel while
still maintaining control of the ve-
hicle.
The front passenger sit as far back
as possible from the dashboard.
All vehicle occupants be properly
restrained using the available seat
belts.This indicator comes on when the igni-
tion key is turned to the ”ACC” or
”ON” position. It goes off after about
6 seconds. This means the SRS airbags
are operating properly.
The SRS airbag warning light system
monitors the airbag sensor assembly, in-
flators, warning light, interconnecting wir-
ing and power sources. (For details, see
”Service reminder indicators and warning
buzzers” in Chapter 1−5.)The SRS airbag system is designed to
activate in response to a severe frontal
impact within the shaded area between
the arrows in the illustration.
There may be the case that the SRS air-
bags will not activate with such an impact
in which the occupant wearing the seat
belt correctly would not get serious injury.
The SRS airbags will deploy if the severi-
ty of the impact is above the designed
threshold level, comparable to an approxi-
mate 25 km/h (15 mph) collision when
impacting straight into a fixed barrier that
does not move or deform.
If the severity of the impact is below the
above threshold level, the SRS airbags
may not deploy.
ProCarManuals.com

name. SIENNA (45403U)
68
However, this threshold velocity will be
considerably higher if the vehicle strikes
an object, such as a parked vehicle or
sign pole, which can move or deform on
impact, or if it is involved in an underride
collision (e.g. a collision in which the nose
of the vehicle ”underrides”, or goes under,
the bed of a truck, etc.).
It is possible with collision severity at the
marginal level of airbag sensor detection
and activation that only one of your ve-
hicle’s two airbags will deploy.
For the safety of all occupants, be sure
to always wear seat belts.
Collision from
the rear
Collision from the side
Vehicle roll−over
The SRS airbags are not designed to
inflate if the vehicle is subjected to a
side or rear impact, if it rolls over, or
if it is involved in a low−speed frontal
collision.
Landing hard or vehicle falling Hitting a curb, edge
of pavement or
hard materialFalling into or
jumping over
a deep hole
The SRS airbags may deploy if a seri-
ous impact occurs to the underside of
your vehicle. Some examples are shown
in the illustration.
ProCarManuals.com

name. SIENNA (45403U)
69
The SRS airbag system mainly consists of
the following components and their loca-
tions are shown in the illustration.
1. Front airbag sensors
2. Airbag module for driver (airbag and
inflator)
3. Airbag module for passenger (airbag
and inflator)
4. Airbag sensor assembly
5. SRS airbag warning light
The airbag sensor assembly consists of a
safing sensor and airbag sensor.In a severe frontal impact, sensors detect
deceleration and the system triggers the
airbag inflators. Then a chemical reaction
in the inflators momentarily fills the air-
bags with non−toxic gas to help restrain
the forward motion of the occupants.
When the airbags inflate, they produce a
fairly loud noise and release some smoke
and residue along with non−toxic gas. This
does not indicate a fire. This gas is nor-
mally harmless, however, for those who
have delicate skin, it may cause minor
skin irritation. Be sure to wash off any
residue as soon as possible to prevent
minor skin irritation.
Deployment of the airbags happens in a
fraction of a second, so the airbags must
inflate with considerable force. While the
system is designed to reduce serious inju-
ries, it may also cause minor burns or
abrasions and swellings.
Parts of the airbag module (steering wheel
hub, dashboard) may be hot for several
minutes, but the airbags themselves will
not be hot. The airbags are designed to
inflate only once.A crash severe enough to inflate the air-
bags may break the windshield as the
vehicle buckles. In vehicles with a pas-
senger airbag the windshield may also be
damaged by absorbing some of the force
of the inflating airbag.
ProCarManuals.com

name. SIENNA (45403U)
72
Do not put objects or your pets on
or in front of the dashboard or
steering wheel pad that houses the
airbag system. They might restrict
inflation or cause death or serious
injury as they are projected rear-
ward by the force of the deploying
airbags. Likewise, the driver and
front passenger should not hold
things in their arms or on their
knees.
Do not modify or remove any wir-
ing. Do not modify, remove, strike
or open any components such as
the steering wheel pad, steering
wheel, column cover, front passen-
ger airbag cover, front passenger
airbag or airbag sensor assembly.
Doing any of these may cause sud-
den SRS airbag inflation or disable
the system, which could result in
death or serious injury.
Failure to follow these instructions
can result in death or serious inju-
ries.NOTICE
Do not perform any of the following
changes without consulting your
Toyota dealer. Such changes can
interfere with proper operation of the
SRS airbag system in some cases.
Installation of electronic items such
as a mobile two−way radio, cassette
tape player or compact disc player
Modification of the suspension sys-
tem
Modification of the front end struc-
ture
Attachment of a grille guard (bull
bar, kangaroo bar, etc.), snowplow,
winches or any other equipment to
the front end
Repairs made on or near the front
fenders, front end structure, con-
sole, steering column, steering
wheel or dashboard near the front
passenger airbag
ProCarManuals.com

name. SIENNA (45403U)
103
Part 1
OPERATION OF
INSTRUMENTS AND
CONTROLS—
Chapter 1−4
Lights, Wipers and
Defogger
Headlights and turn signals
Emergency flashers
Instrument panel light control
Personal lights
Interior light
Ignition switch light
Luggage compartment light
Windshield wipers and washer
Rear window wiper and washer
Rear window and outside
rear view mirror defoggers
HEADLIGHTS
To turn on the following lights: Twist
the headlight/turn signal lever knob.
Position 1—Parking, tail, license plate,
side marker and instrument panel lights
Position 2—Headlights and all of the
above
Position 3 (”AUTO”)—Headlights and/or all
of the above
They automatically turn on or off depend-
ing on the darkness of the surroundings.
Manually twist the knob to the position 2
to turn on the headlights if they are need-
ed immediately when entering a dark tun-
nel, parking structure, etc.The automatic light control sensor is on
the top of the driver’s side instrument
panel.
Do not place anything on the instrument
panel, and/or do not affix anything on the
windshield to block this sensor.
If you feel that the automatic light control
comes into operation too early or too late,
have the sensor adjusted by your Toyota
dealer.
Headlights and turn signals
(with automatic light control
system)
ProCarManuals.com

name. SIENNA (45403U)
11 9
(a) Brake System Warning Light
This light has the following functions:
Parking brake reminder
If this light is on, make sure the parking
brake is fully released. The light should
go off.
Low brake fluid level warning
If this light comes on and stays on while
you are driving, slow down and pull off
the road. Then stop the vehicle carefully.
Remember that stopping distance and ped-
al effort may be increased. There maybe
a problem somewhere in the brake sys-
tem. Check the fluid level of the see−
through reservoir.
To make sure the parking brake has not
caused the warning light to come on,
check to see that the parking brake is
fully released.
If the brake fluid level is low...
At a safe place, test your brakes by start-
ing and stopping.
If you judge that the brakes still work
adequately, drive cautiously to your
nearest dealer or shop for repairs.
If the brakes are not working, have the
vehicle towed in for repairs. (For tow-
ing information, see Part 4.)
CAUTION
It is dangerous to continue driving
normally when the brake fluid level is
low.
If the brake fluid level is correct...
Have the warning system checked by your
Toyota dealer.
(b) Driver’s Seat Belt Reminder Light
and Buzzer
The light and buzzer remind you to buckle
up the driver ’s seat belt.
Once the ignition key is turned to ”ON” or
”START”, the reminder light flashes and
buzzer sounds if the driver ’s seat belt is
not pulled out. Unless the driver starts to
pull the shoulder belt out of the retractor,
the light keeps flashing and the buzzer
stops after about 4 to 8 seconds.
(c) Front Passenger ’s Seat Belt Re-
minder Light
The light reminds you to buckle up the
front passenger ’s seat belt.Once the ignition key is turned to ”ON” or
”START”, the reminder light flashes if a
passenger sits in the front passenger seat
and does not pull out the seat belt. Un-
less the front passenger starts to pull the
shoulder belt out of the retractor, the light
stays flashing.
If luggage load is placed on the front
passenger seat, depending on its weight
and how it is placed on the seat, built−in
sensors in the seat cushion may detect
the pressure, causing the reminder light to
come on.
(d) Discharge Warning Light
This light warns that the battery is being
discharged.
If it comes on while you are driving, there
is a problem somewhere in the charging
system.
The engine ignition will continue to oper-
ate, however, until the battery is dis-
charged. Turn off the air conditioning,
blower, radio, etc., and drive directly to
the nearest Toyota dealer or repair shop.
NOTICE
Do not continue driving if the engine
drive belt is broken or loose.
ProCarManuals.com