Lexus RX300 (MCU15). Service manual - part 523

RS0RU–01

H17194

R09725

Spiral Cable

H05057

H05058

H05059

RS–2

–

SUPPLEMENTAL RESTRAINT SYSTEM

SRS AIRBAG

LEXUS RX300   (RM785E)

OPERATION

1.

STEERING WHEEL PAD (with AIRBAG)

The inflater and bag of the SRS are stored in the steering wheel
pad and cannot be disassembled. The inflater contains a squib,
igniter charge, gas generator, etc., and inflates the bag when
instructed by the airbag sensor assembly.

2.

SPIRAL CABLE (in COMBINATION SWITCH)

A spiral cable is used as an electrical joint from the vehicle body
side to the steering wheel.

3.

FRONT PASSENGER AIRBAG ASSEMBLY

The inflater and bag of the SRS are stored in the front passen-
ger airbag assembly and cannot be disassembled. The inflater
contains a squib, igniter charge, gas generator, etc., and in-
flates the bag when instructed by the airbag sensor assembly.

4.

SIDE AIRBAG ASSEMBLY

The inflater and bag of the SRS side airbag are stored in the
side airbag assembly and cannot be disassembled. The inflater
contains a squib, igniter charge, gas generator, etc., and in-
flates the bag when instructed by the side airbag sensor assem-
bly.

5.

SEAT BELT PRETENSIONER

The seat belt pretensioner system is a component of the front
seat outer belt. The pretensioner contains a squib, gas genera-
tor, wire, piston, etc., and operates in the event of a frontal colli-
sion. The seat belt pretensioner cannot be disassembled.

H05060

H05061

H17185

H05062

–

SUPPLEMENTAL RESTRAINT SYSTEM

SRS AIRBAG

RS–3

LEXUS RX300   (RM785E)

6.

SRS WARNING LIGHT

The SRS warning light is located on the combination meter. It
goes on to alert the driver of trouble in the system when a mal-
function is detected in the airbag sensor assembly self–diagno-
sis. In normal operation conditions when the ignition switch is
turned to the ON position, the light goes on for about 6 seconds
and then goes off.

7.

AIRBAG SENSOR ASSEMBLY

The airbag sensor assembly is mounted on the floor inside the
lower center finish panel. The airbag sensor assembly consists
of an airbag sensor, safing sensor, diagnosis circuit, ignition
control, drive circuit, etc. It receives signals from the airbag sen-
sor, front airbag sensor, side airbag sensor assembly and door
side airbag assembly and judges whether the SRS must be ac-
tivated or not. The airbag sensor assembly cannot be disas-
sembled.

8.

FRONT AIRBAG SENSOR

The front airbag sensor is mounted inside each of the side
members. The sensor unit is a mechanical type. When the sen-
sor detects deceleration force above a predetermined limit,
contact is made in the sensor, sending a signal to the airbag
sensor assembly. The front airbag sensor cannot be disas-
sembled.

9.

SIDE AIRBAG SENSOR ASSEMBLY

The side airbag sensor assembly is mounted in the LH and RH
center pillars. The side airbag sensor assembly consists of a lat-
eral deceleration sensor, safing sensor, diagnosis circuit, etc.
It sends signals to the airbag sensor assembly to judge whether
the SRS side airbag must be activated or not. The side airbag
sensor assembly cannot be disassembled.

H16279

Airbag Sensor 
Assembly

1

2

3

8

9

10

Side Airbag 
Assembly (RH) (Squib)

11

12

14

Seat Belt 
Pretensioner (RH)

Side Airbag Sensor 
Assembly (RH)

Front Airbag Sensor (RH)

4

5

Front Passenger Airbag 
Assembly (Squib)

Spiral Cable

7

Steering Wheel
Pad (Squib)

6

15

Front Airbag Sensor (LH)

Side Airbag Sensor 
Assembly (LH)

Seat Belt 
Pretensioner (LH)

Side Airbag 
Assembly (LH) (Squib)

13

RS–4

–

SUPPLEMENTAL RESTRAINT SYSTEM

SRS AIRBAG

LEXUS RX300   (RM785E)

10.

SRS CONNECTORS

HINT:
SRS connectors are located as shown in the following illustra-
tion.

No.

Item

Application

(1)

Terminal Twin–Lock Mechanism

Connectors 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15

(2)

Airbag Activation Prevention Mechanism

Connectors 1, 2, 3, 4, 5, 6, 8, 9, 13, 14

(3)

Electrical Connection Check Mechanism

Connectors 1, 2, 3

Z05953

Spacer

Housing

Female

Male

R10587

When Connector is Connected

When Connector is Disconnected

Short Spring Plate

Housing

Housing

Terminal

Connectors

Short Spring Plate

Squib

Closed Circuit

Squib

Short Spring Plate ON

Contacting Male Terminal

Short Spring Plate

–

SUPPLEMENTAL RESTRAINT SYSTEM

SRS AIRBAG

RS–5

LEXUS RX300   (RM785E)

(a)

All connectors in the SRS are colored in yellow to distin-
guish them from other connectors. Connectors having
special functions and specifically designed for the SRS
are used in the locations shown on the previous page to
ensure high reliability. These connectors use durable
gold–plated terminals.

(1)

Terminal Twin–Lock Mechanism
Each connector has a two–piece component con-
sisting of a housing and a spacer. This design en-
ables the terminal to be locked securely by two lock-
ing devices (the retainer and the lance) to prevent
terminals from coming out.

(2)

Airbag Activation Prevention Mechanism
Each connector contains a short spring plate. When
the connector is disconnected, the short spring
plate automatically connects positive (+) terminal
and negative (–) terminal of the squib.