Lexus RX300 (MCU15). Service manual - part 300

H01026

H06508

H06509

Airbag Sensor 
Assembly

Side Airbag

Sensor (RH)

Spiral

Cable

Front  Airbag

Sensor (RH)

P Squib

LOCK

D Squib

Front Airbag

Sensor (LH)

P/T Squib (LH)

Side Airbag

Sensor (LH)

Side Squib (LH)

P/T Squib (RH)

Side Squib (RH)

DI–432

–

DIAGNOSTICS

SUPPLEMENTAL RESTRAINT SYSTEM

LEXUS RX300   (RM785E)

INSPECTION PROCEDURE

1

Prepare for inspection.

PREPARATION:
(a)

Disconnect negative (–) terminal cable from the battery,
and wait at least for 90 seconds.

(b)

Remove the steering wheel pad (See page SR–12).

(c)

Disconnect the connector of the front passenger airbag
assembly (See page RS–27).

(d)

Disconnect the connector of the side airbag assembly RH
and LH (See page RS–39).

(e)

Disconnect the connector of the seat belt pretensioner
RH and LH (See page BO–189).

(f)

Disconnect the connectors of the airbag sensor assembly
(See page RS–52).

(g)

Disconnect the connector of the front airbag sensor RH
and LH (See page RS–57).

(h)

Disconnect the connector of the side airbag sensor as-
sembly RH and LH (See page RS–62).

CAUTION:
Store the steering wheel pad, front passenger airbag as-
sembly and side airbag assemlby with the front surface
facing upward.

AB0119
H01298

H01299

Airbag Sensor Assembly

ON

IG1

IG2

(+)

(–)

H01249

ON

–

DIAGNOSTICS

SUPPLEMENTAL RESTRAINT SYSTEM

DI–433

LEXUS RX300   (RM785E)

2

Check source voltage.

PREPARATION:
Connect negative (–) terminal cable to the battery.
CHECK:
(a)

Turn the ignition switch to ON.

(b)

Measure the voltage between body ground and each of
IG1 and IG2 on the sensor and operate electric system
(defogger, wiper, headlight, heater blower, etc.).

OK:

Voltage: 10 – 14 V

NG

Check harness between battery and airbag sen-
sor assembly, and check battery and charging
system.

OK

3

Does SRS warning light turn off?

PREPARATION:
(a)

Turn the ignition switch to LOCK.

(b)

Connect the steering wheel pad connector.

(c)

Connect the front passenger airbag assembly connector.

(d)

Connect the side airbag assembly connectors.

(e)

Connect the seat belt pretensioner connectors.

(f)

Connect the airbag sensor assembly connectors.

(g)

Connect the front airbag sensor connectors.

(h)

Connect the side airbag sensor assembly connectors.

(i)

Turn the ignition switch to ON.

CHECK:
Operate electric system (defogger, wiper, headlight, heater
blower, etc.) and check that SRS warning light goes off.

NO

Check for DTCs. If a DTC is output, perform trou-
bleshooting for the DTC. If a normal code is out-
put, replace airbag sensor assembly.

YES

From the results of the above inspection, the malfunctioning part can now be considered normal.
To make sure of this, use the simulation method to check.

H16260

Battery

Airbag Sensor 
Assembly

W–L

B–Y

LA

IG1

3

Ignition SW

AM2

F11 FL Block

R–W

5

C11 
SRS Warning Light

ALT

1C

7

13

19

W

5

1K

1K

2

4

3A

3E

1

B–Y

1L

J/B No. 3

1

Instrument Panel J/B

HEATER

B–Y

2

A28

6

1C

1A

1

1

2

AM1

5

W

R–W

DI–434

–

DIAGNOSTICS

SUPPLEMENTAL RESTRAINT SYSTEM

LEXUS RX300   (RM785E)

SRS Warning Light Circuit Malfunction

CIRCUIT DESCRIPTION

The SRS warning light is located on the combination meter. 
When the SRS is normal, the SRS warning light lights up for approx. 6 seconds after the ignition switch is
turned from the LOCK position to ON position, and then turns off automatically. 
If there is a malfunction in the SRS, the SRS warning light lights up to inform the driver of the abnormality.
When terminals Tc and CG of the DLC3 are connected, the DTC is displayed by blinking the SRS warning
light.

WIRING DIAGRAM

DI6PZ–06

AB0117

H01293

H01295

Airbag Sensor Assembly

LOCK

–

DIAGNOSTICS

SUPPLEMENTAL RESTRAINT SYSTEM

DI–435

LEXUS RX300   (RM785E)

INSPECTION PROCEDURE
Always lights up, when ignition switch is in LOCK position

1

Prepare for inspection (See step 1 on page DI–431).

2

Does SRS warning light turn off?

PREPARATION:
(a)

Turn the ignition switch to LOCK.

(b)

Disconnect negative (–) terminal cable from the battery,
and wait at least for 90 seconds.

(c)

Disconnect the airbag sensor assembly connector.

(d)

Connect negative (–) terminal cable to the battery.

CHECK:
Check operation of SRS warning light.

NO

Check SRS warning light circuit or terminal AB
circuit of DLC3.

YES

Replace airbag sensor assembly.