Lexus RX300 (MCU15). Service manual - part 70

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BODY ELECTRICAL — ACCESSORIES

153

JSRS AIRBAG SYSTEM

D The SRS (Supplemental Restraint System) airbags are provided for the driver and front passenger.

The SRS airbags help to reduce injuries mainly to the driver’s or front passenger’s head or chest in the
event of a frontal impact collision as supplements to the seat belts.
This system is a 3-sensor type airbag system to detect the impact during a front collision using the airbag
sensor assembly and front airbag sensor, and to make the airbag system and seat belt pretensioner operate
as well.

D The SRS side airbags are provided for the driver and front passenger. The SRS side airbag help to reduce

injuries mainly to the driver’s or front passenger’s chest in the event of a side collision.
The driver side and the front passenger side are each provided with one sensor.

D The RX300 has adopted a fuel cut control that stops the fuel pump when the SRS driver’s and front

passenger’s airbags are deployed.

" Layout of Components A

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Front Airbag Sensor
Assembleies

Inflator and Bag 
(for Front Passenger)

Side Airbag Assembly

Side Airbag Sensor
Assembly

Seat Belt Pretensioner

Side Airbag Assembly

Seat Belt Pretensioner

Side Airbag Sensor
Assembly

Airbag
Sensor
Assembly

" System Diagram A

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Collision

Impact

Front Airbag
Sensor Assembly

Airbag Sensor
Assembly

• Inflator (For Driver

and Front Passenger)

• Seat Belt Pretensioner

(LH and RH)

Inflator
(For Right Side or Left Side)

Side Airbag
Sensor
Assembly

Collision

Impact

BODY ELECTRICAL — ACCESSORIES

154

JSEAT BELT WARNING SYSTEM

1. General

The seat belt warning system illuminates the driver warning light and flashes the front passenger warning
light to inform the driver and front passenger that the seat belt have not been fastened.
When the ignition switch is turn ON, this system determines whether or not the seat belt is buckled by
the ON or OFF condition of the switch that is provided in the seat belt buckle. The occupant detection
sensor provided in the seat cushion of the front passenger seat determines whether or not an occupant is
seated in the front passenger seat.

" System Diagram A

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Front Passenger Side

Combination
Meter

BEAN

Body ECU

Seat Belt
Buckle
Switch

Driver Side

Seat Belt
Warning Light

Occupant
Detection Sensor

Seat Belt
Buckle
Switch

2. 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 electrodes
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.

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Occupant Detection Sensor

Front Passenger Seat

Upside View

Spacer

Electrode Sheet

Electrode Sheet

Sensor OFF

Occupant

Sensor ON

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159BE18

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BODY ELECTRICAL — ACCESSORIES

155

JCRUISE CONTROL SYSTEM

1. General

Once the system is set to a desired vehicle speed, the engine throttle position is adjusted automatically
to maintain the vehicle speed at that speed without depressing the accelerator pedal.
This system is optional equipment.

2. Layout of Components

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Cruise Control ECU

Cruise Control Switch

LHD Model

Cruise Control ECU

Cruise Control
Switch

RHD Model

Cruise Control
Actuator

Neutral Start Switch

Stop Light Switch

Stop Light
Switch

3. Function

The cruise control ECU has the following functions.

" Functions A

Function of cruise control ECU

1

Constant Speed Control

6

Low Speed Limit Control

11

Magnetic Clutch Control

2

Set

7

High Speed Limit Control

12

Diagnosis

3

Coast

8

Automatic Transmission
Control

13

Fail Safe

4

Accel

9

Manual Cancel

14

Tap-Down Control

5

Resume

10

Auto Cancel

15

Tap-Up Control

BODY ELECTRICAL — ACCESSORIES

156

JAUTOMATIC GLARE–RESISTANT EC MIRROR SYSTEM

1. General

This system automatically reduces the reflection rate of the inner and outside mirrors by using an EC (electro-
chromic) element to dampen the bright glare of the headlights of the vehicle driving behind. This system
is optional equipment.

2. Layout and Function of Components

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Detection 
Sensor
(No. 2 Sensor)

EC Mirror Cell

Rear Light Detection Sensor
(No. 2 Sensor)

Surrounding Light Detection Sensor
(No. 1 Sensor)

Inner Rear View Mirror

Surrounding Light
Detection Sensor
(No. 1 Sensor)

Outside Rear View Mirror
(RH)

Mode Select Switch

EC Mirror Cell

EC Mirror Cell

Outside Rear View Mirror
(LH)

LED

Rear Light

Components

Function

LED

Turns on to inform the driver that the mirror control mode is
operating in the AUTO mode.

Mode Select Switch

Selects the inner and outside mirror control to AUTO or DAY
mode.

EC Mirror Cell

Varies the reflection rate of the mirror through the function of
electrochromic elements.

Surrounding Light Detection Sensor
(No. 1 Sensor)

Detects the intensity of the light surrounding the vehicle.

Rear Light Detection Sensor 
(No. 2 Sensor)

Detects the intensity of the light entering the inner mirror
from behind the vehicle.