Page 1017 of 4770
1
GENERAL 1999 FEATURES
159EG07
VSV
(for EVAP)Service Port
Intake Air ChamberCharcoal
CanisterFuel Tank3
ENGINE
EMISSION CONTROL SYSTEM
A service port for inspecting the evaporative emission control system has been provided between the charcoal
canister and the VSV for EVAP.
The evaporative emission control system can be inspected by connecting a pressure gauge to the service port
and performing a vacuum or a pressure test.
Refer to the repair manual for the respective model for details on the check method.
Page 1018 of 4770
GENERAL 1999 FEATURES
148BE114
Corolla
160GE07
Collision
ImpactAirbag Sensor
Assembly
Power
Source
Safing
Sensor
Airbag Sensor
Front Airbag
Sensors
To Seat Belt
PretensionerInflator
Squib
Gas
GeneratorGas
Bag
(For Driver)
Inflator
Initiator
Gas
Gas
Bag
(For Front
Passenger) 4
ACCESSORIES
SRS AIRBAG
1. General
The electrically sensing type SRS (Supplemental Restraint System) airbag is designed to help lessen the
shock to the driver and front passenger as a supplement to the seat belt.
A 3-sensor type airbag system detects the deceleration during collision by the front airbag sensors and the
airbag sensor that is enclosed in the airbag sensor assembly.
System Diagram
The activation processes of the
SRS airbag is as illustrated below.
Page 1019 of 4770
1
GENERAL 1999 FEATURES
148BE16
Corolla
Right Side Front
Airbag SensorInflator and Bag for
Front Passenger
(Above the Glove Box)
Airbag Sensor Assembly Inflator and Bag for Driver
(In Steering Wheel Pad) Left Side Front
Airbag Sensor
SRS Warning Light
160GE04
Front Airbag
Sensor (RH)
Battery
Front Airbag
Sensor (LH)
DC-DC
Converter
Back-Up
Power
Source
CPU
Airbag
Sensor
Safing
Sensor
Drive
Circuit
Drive
Circuit
Drive
Circuit
Drive
Circuit
SRS Warning Light
DLC1
Squib (For Driver)
Initiator
(For Front
Passenger)
Spiral Cable
To Seat Belt
Pretensioner Airbag Sensor AssemblyDLC3
5
2. Layout of Components
The major function parts of the airbag systems are shown below.
3. Wiring DIagram
Page 1020 of 4770

GENERAL 1999 FEATURES
160GE06 160GE05
Normal Condition Activated Condition Stationary
Contact PointRotor
Movable
Contact
PointDeceleration
141BE65 148BO127Corolla
Fig. 1
Fig. 2Range of Operation
Front Airbag
Sensor ON / OFF
Safing Sensor
ON
Airbag Sensor
ONAND
Ignition
6
4. Construction and Operation
Front Airbag Sensor
The front airbag sensor consists of rotor, movable contact point and a stationary contact point.
The rotor is fixed by the initial set load of the movable contact point. At the same time, the movable contact
point restrains the movement of the rotor which is generated during vehicle deceleration, thus preventing
the unintended activation of the system.
If a sudden deceleration that exceeds a predetermined value occurs due to a collision of the vehicle, the rotor
will rotate. The rotational movement of the rotor pushes the movable contact point and causes the movable
and stationary contact points to come into contact. As a result, an ON signal is generated and transmitted
to the airbag sensor assembly.
5. System Operation
Ignition Judgement and Condition
When the vehicle collides in the hatched area (Fig. 1) and the shock is larger than a predetermined level,
the airbag and the seat belt pretensioner are activated automatically. The airbag sensor is characteristically
turned in such a way that can judge the need for ignition in collisions within the hatched area.
The safing sensor is designed to be activated by a smaller deceleration rate than that of the airbag sensor.
As illustrated in Fig. 2 below, ignition is operated when current flows to the squib. This happens when a
safing sensor and the airbag sensor go on simultaneously.
Airbag sensor assembly judges whether or not to inflate the airbag in accordance with ON / OFF of the front
airbag sensor and the deceleration detected by the airbag sensor.
Page 1021 of 4770

1
GENERAL 1999 FEATURES
156BE19
156BE20 156BE18
Occupant
Detection Sensor
Front Passenger Seat
Land CruiserSpacerElectrode Sheet
Electrode Sheet
Sensor OFF
Occupant
Sensor ON7
SEAT BELT WARNING SYSTEM
1. General
A seat belt warning for the front passenger has been newly provided. When the front passenger seat is occu-
pied but its seat belt is not being worn, this function flashes a warning light to inform the front passenger that
the seat belt is not being worn.
2. Seat Belt Warning for Front Passenger
Construction
The seat belt warning for the front passenger consists of the front passenger seat belt buckle / retractor
switch, occupant detection sensor, seat belt warning light for the front passenger.
1) Belt Warning Occupant Detection Sensor
The occupant detection sensor, which is enclosed in the seat cushion of the front passenger seat, is used
to detect whether or not the front passenger seat is occupied.
This sensor, which is shaped as illustrated below, consists of a construction in which two sheets of elec-
trodes sandwich a spacer. When the occupant is seated, the electrode sheets come in contact with each
other through the hole that is provided in the spacer portion, thus enabling the current to flow.
Thus, the sensor detects whether or not an occupant is seated in the front passenger seat.
Page 1022 of 4770

GENERAL 1999 FEATURES
156BE14
Warning Light for
Front Passenger
Land Cruiser 8
2) Front Passenger Seat Belt Buckle / Retractor Switch
The front passenger seat belt buckle / retractor switch is enclosed in the seat belt buckle / retractor of the
front passenger seat to detect whether or not the seat belt for the front passenger is being worn.
3) Seat Belt Warning Light for Front Passenger
The seat belt warning light for front passenger flashes to warn if the front passenger does not have the
seat belt buckled.
Operation
When an occupant is seated in the front passenger seat, the occupant detection sensor activates, thus enab-
ling the system to recognize that the occupant has seated. When the ignition switch is turned ON, a warning
light flashes if the front passenger is not wearing the seat belt. The warning light continues to flash until
the front passenger wears the seat belt.
If the front passenger seat is not occupied, the warning light remains extinct regardless of the condition of
the seat belt.
Page 1023 of 4770

1
GENERAL 1999 FEATURES9
AUDIO
AVC-LAN
1. General
The AVC-LAN (Audio Visual Communication - Local Area Network) is a communication standard that has
been established by the 6 audio manufacturers that produce audio visual units, which are mounted on Toyota's
production vehicles. This standard, which ensures the mutual interchangeability of the manufacturers' units,
facilitates the connection and control of those units.
The characteristics of an audio system that supports AVC-LAN are described below.
An audio system can be created by selecting the units regardless of the audio unit's manufacturer.
The audio system that was installed in the factory can be freely interchanged or added with commercially
available audio units.
Because this standard enables the manufacturers to develop and produce the audio unit of their specialty,
a wide variety of products can be provided in the audio lineup.
The audio units that are newly developed by the manufacturers can be added to the lineup in a timely man-
ner.
By pre-registering the switch operation of each unit established in the line up into the head unit, each unit
can be controlled by the head unit without adding the transmitter when adding units later.
By adopting the audio system corresponded to the AVC-LAN standard, audio units can be easily added or
changed with the audio system mounted originally on the vehicle as the base. Thus, the expandability of the
audio system is improved.
Page 1024 of 4770

GENERAL 1999 FEATURES
160GE01
Radio and Cassette DeckCommunication BusCD Changer
Physical Address : 190
Logical Address : 11 (Mode Control)
25 (Command Switch)
60 (Radio Tuner)
61 (Cassette Deck)Physical Address: 240
Logical Address: 43 10
2. Communication Outline
In the audio system that uses AVC-LAN, audio units such as a cassette deck or a CD changer are connected
by a communication bus that establishes communication via serial data signals.
In this system, addresses are used to identify the units with which to establish communication. The addresses
can be broadly divided into two types: the physical address that is assigned to each audio unit such as a cas-
sette deck, CD changer, etc.; and the logical address that is assigned to the function that each unit provides,
such as the radio function or the cassette function. The physical addresses are represented by 3-digit numbers
and the logical addresses are represented by 2-digit numbers.
The signals that are exchanged between the units are the unit's control signal, display data, audio signal, etc.,
which have been rendered into serial data. The configuration of the 4 signals indicated below, which are ren-
dered into serial data and transmitted to the each unit, has been established as a uniform AVC-LAN standard.
Audio Signal
Video Signal
Display Data
Signal Communication Software
The illustration below shows an example of an audio system configuration using AVC-LAN.
3. Operation
System Registration
An audio system that uses AVC-LAN performs a registration process to verify the audio units that comprise
the system.
When the ignition switch is turned to the ACC position, the audio units that comprise the system transmit
the logic address in the units, and the physical address is transmitted by the mode control portion that is
integrated in the smallest audio unit (head unit). By receiving these addresses, the mode control portion veri-
fies the units that comprise the system.
By performing this process, all functions can be controlled regardless of the combination of the units that
comprise the system.