sensor TOYOTA CAMRY 2000 Service Repair Manual

CAMRY ± NEW FEATURES
150NF105 150NF104Inactive Activated Wire
PulleyDrum
Piston
Cylinder
15
SEAT BELT
1. General
The front seats are provided with an electrical sensing type seat belt pretensioner and a seat belt force limiter.
In the beginning of a collision, the seat belt pretensioner instantly pulls up the seat belt thus providing the
excellent belt's effectiveness in restraining the occupant.
When the impact of a collision causes the tension of the seat belt applied to the occupant to reach a predeter-
mined level, the force limiter restrains the tension, thus controlling the force applied to the occupant's chest
area.
In accordance with the ignition signal from the airbag sensor assembly, the seat belt pretensioner activates
simultaneously with the deployment of the
SRS airbags for the driver and front passenger.
2. Seat Belt Pretensioner
Construction and Operation
The seat belt pretensioner consists of the pretensioner mechanism and retracting mechanism.
The pretensioner mechanism consists of a gas generator, piston, wire, drum and etc.
If the airbag sensor is turned on by deceleration due to frontal collision, electric current then ignites the gas
generator located in the pretensioner. As a result, the gas generator emits gas in an extremely short time and
pushes the piston. Since the cable is attached to the piston, the piston will pull on the cable causing the drum
to grab onto the shaft. The shaft will then move in the retracting direction pulling up the belt for a predeter-
mined length.

CAMRY ± NEW FEATURES
150NF109
150NF110
Side Collision ImpactLeft Side Airbag
Sensor Assembly
Power
Source
Safing
Sensor
Side Airbag
SensorInitiator
Bag
(For Driver) Gas
Inflator
Airbag Sensor
AssemblyCPU
Drive
Circuit
17
SRS SIDE AIRBAG
1. General
In conjunction with the energy absorbing doors, the SRS side airbags have been designed to help reducing
the impact energy that is transmitted to the driver and front passenger in the event of a side collision. In
a side collision, the side airbag sensor detects the shock and if the side-to-side shock is greater that a speci-
fied value, the airbags stored in the seat back for the driver and the front passenger inflate instantly to help
reducing the likelihood of the driver's or front passenger's arm and chest directly hitting the door trim.
Each
SRS side airbag is independent of the other.
An electrical type
SRS side airbag, in which the side airbag is activated by the ignition signal emitted by
the airbag sensor assembly, has been adopted.

System Diagram 
The activation processes of the SRS side airbag is as illustrated below.

CAMRY ± NEW FEATURES
150NF111
SRS Warning
LightAirbag Sensor
AssemblyRight Side Airbag
Assembly
Right Side Airbag
Sensor Assembly
Left Side Airbag
Sensor Assembly Left Side
Airbag Assembly
150NF112
BatterySide Airbag Sensor
Assembly (LH)
Initiator
(LH)
Back-Up
Power Source
DC-DC
Converter
CPU
Airbag Sensor AssemblyInitiator
(RH) Side Airbag Sensor
Assembly (RH)
SRS Warning Light
Drive
Circuit
Communication
Circuit
Drive
CircuitSafing
Sensor
Drive
Circuit
Drive
Circuit
DLC1
Power
Control
Ignition Switch
Communication
Circuit
Power
Control
18
2. Layout of Components
The major function parts of the side airbag system are shown below.
3. Wiring Diagram

CAMRY ± NEW FEATURES19
4. Construction and Operation
Side Airbag Sensor Assembly
1) Description
The side airbag sensor assembly is mounted on the right and left center pillars. It receives signals from
the side airbag sensor enclosed in the side airbag sensor assembly and judges whether the side airbag must
be activated or not.
2) Construction and Operation
The side airbag sensor assembly consists of side airbag sensor, safing sensor, etc.
a. Side Airbag Sensor
The side airbag sensor is enclosed in the side airbag sensor assembly based on the acceleration of the
vehicle that occurs during a side collision. The distortion created in the sensor is converted into an elec-
tric signal. This signal is a linear representation of the acceleration rate.
b. Safing Sensor
The safing sensor is enclosed in the side airbag sensor assembly. The sensor turns ON if an acceleration
force that is higher than a predetermined value is applied to the safing sensor as a result of a side colli-
sion.
Airbag Sensor Assembly
1) Description
The airbag sensor assembly is mounted on the center floor under the instrument panel.
When the airbag sensor assembly receives the airbag activation signal from the side airbag sensor assem-
bly, it applies current to the inflator.
Furthermore, the airbag sensor assembly diagnoses a system malfunction of the side airbag system.
This is the same airbag sensor assembly that is used for the
SRS airbag for the driver and front passenger.
2) Construction and Operation
The airbag sensor assembly consists of ignition control circuit, back up power source, diagnosis circuit,
memory circuit, etc.
a. Ignition Control Circuit
The ignition control circuit performs a prescribed calculation based on the signal output by the airbag
sensor and the front airbag sensor. If these calculated values are larger than a predetermined value, it
activates the ignition operation.
b. Back-Up Power Source
The back-up power source consists of a back-up capacitor and a DC-DC converter. In case of a power
system failure during a collision, the back-up capacitor discharges and supplies electric power to the
system. The DC-DC converter is a boosting transformer when the battery voltage drops below a certain
level.
c. Diagnosis Circuit
This circuit constantly diagnoses the system for any malfunction. When a malfunction is detected, it
lights up the
SRS warning light on the combination meter to alert the driver.
d. Memory Circuit
When a malfunction is detected by the diagnosis circuit, it is coded and stored in this memory circuit.

CAMRY ± NEW FEATURES
150NF122
Pressure BulkheadPropellant Grain
Gas
Initiator
CAUTION
The initiator is ignited even by a feeble current. As it is dangerous, never measure the resistance of the
initiator with a volt / ohmmeter, etc.
150NF123
Pressure Bulkhead
Propellant GrainInitiator
Gas
: Propagation of Fire
: Flow of Gas
20
Inflator and Bag
1) Construction
The inflator and bag are integrated inside the case and located in the outer side of the seat back. The infla-
tor is comprised of a initiator, propellant grain, gas and pressure bulkhead.
The bag is made of strong nylon cloth and becomes inflated by the gas heated by the inflator.
2) Operation
When the side airbag sensor detects the acceleration because of a side collision, the ECU appraises the
extent of the acceleration to determine whether or not the side airbag must be deployed.
After the ECU determines that the side airbag must be delpoyed, it causes the initiator to ignite in order
to head and expand the gas inside the inflator. The expanded gas tears thhe pressure bulkhead and flows
into the bag.
The bag, which is inflated by the gas, pushes open the case in the seat, tears the sewn portion of the seat
outer cover, and expands to the side of the occupant.
The expanded bag receives the occupant's arm and chest, and discharges the gas through the bag's surface
in order to soften the rcoil.
Thus, the side airbag helps to reduce the impact energy that is applied to the occupant's arm and chest
areas.

CAMRY ± NEW FEATURES
150NF113
SRS Warning Light
150NF114
Range of Operation
Safing
Sensor ON
Side Airbag
Sensor ON
ANDIgnition
21
SRS Warning Light
The
SRS warning light is located on the
combination meter.
It comes on to alert the driver about system
trouble when a malfunction is detected in
self-diagnosis of the airbag sensor assembly and
side airbag sensor assembly. In normal operating
conditions when the ignition switch is turned to
the ACC or ON position, the light comes on for
about 6 seconds and then goes off.
5. System Operation
Ignition Judgement and Conditions
The safing sensor is designed to be activated by a smaller acceleration rate than the side airbag sensor.
As illustrated below, ignition is caused when current flows to the initiator, which happens when a safing
sensor and the side airbag sensor go on simultaneously.

'99camry U
37
To connect the extender to the seat
belt, insert the tab into the seat belt
buckle so that the ºPRESSº signs on
the buckle±release buttons of the ex-
tender and the seat belt are both facing
outward as shown.
You will hear a click when the tab locks
into the buckle.
When releasing the seat belt, press on
the buckle±release button on the extender,
not on the seat belt. This helps prevent
damage to the vehicle interior and extend-
er itself.
When not in use, remove the extender
and store in the vehicle for future use.
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.
ÐFront 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.

'99camry U
38
This indicator comes on when the igni-
tion key is turned to the ºACCº or
ºONº position. It goes off after about
6 seconds. This means the front seat
belt pretensioners are operating proper-
ly.
This warning light system monitors the
front airbag sensors, airbag sensor as-
sembly, seat belt pretensioner assembly,
warning light, interconnecting wiring and
power sources. (For details, see ºService
reminder indicators and warning buzzersº
in Chapter 1±5.)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 serious injury.
Failure to follow these instructions
can result in serious injuries.

'99camry U
40
The SRS (Supplemental Restraint Sys-
tem) airbags are designed to provide
further protection for the driver and
front passenger when added to the pri-
mary protection provided by the seat
belts.
In response to a severe frontal impact,
the SRS airbags work together with the
seat belts to help prevent or reduce injury
by inflating, in order to decrease the likeli-
hood of the driver 's or front passenger 's
head or chest directly hitting the steering
wheel or dashboard. The passenger airbag
is activated even with no passenger in the
front seat.
Be sure to wear your seat belt.
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 ºACCº or
ºONº position. It goes off after about
6 seconds. This means the SRS airbags
are operating properly.
The SRS airbag warning light system
monitors the front airbag sensors, airbag
sensor assembly, inflators, warning light,
interconnecting wiring and power sources.
(For details, see ºService reminder indica-
tors and warning buzzersº in Chapter
1±5.)
SRS driver and front
passenger airbags

'99camry U
41
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-
bag 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.
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 ºunderridesº, 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 sideCollision from rear
Vehicle rollover
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.