Lexus RX300 (MCU15). Service manual - part 301

N14677

Fuse

AB0119
H01300

H01301

Airbag Sensor Assembly

ON

LA

(+)

(–)

DI–436

–

DIAGNOSTICS

SUPPLEMENTAL RESTRAINT SYSTEM

LEXUS RX300   (RM785E)

Does not light up, when ignition switch is turned to ON

1

Check AM2 Fuse.

PREPARATION:
Remove the AM2 fuse.
CHECK:
Check continuity of the AM2 fuse.
OK:

Continuity

HINT:

S

Fuse may be burnt out even if it appears to be OK during
visual inspection.

S

If fuse is OK, install it.

NG

Go to step 5.

OK

2

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

3

Check SRS warning light circuit.

PREPARATION:
(a)

Connect negative (–) terminal cable to the battery.

(b)

Turn the ignition switch to ON.

CHECK:
Measure the voltage between body ground and LA terminal of
the harness side connector of the airbag sensor assembly.
OK:

Voltage: 10 – 14 V

NG

Check SRS warning light bulb or repair SRS
warning light circuit.

OK

AB0119 H05060

H16274

H16793

P Squib

D Squib

P/T Squib (LH)

P/T Squib (RH)

Side Squib (LH)

Side Squib (RH)

Spiral
Cable

Front Airbag 
Sensor (RH)

Front Airbag 
Sensor (LH)

Side Airbag 
Sensor (LH)

Side Airbag 
Sensor (RH)

ON

Airbag Sensor
Assembly

–

DIAGNOSTICS

SUPPLEMENTAL RESTRAINT SYSTEM

DI–437

LEXUS RX300   (RM785E)

4

Does SRS warning light come on?

PREPARATION:
(a)

Disconnect negative (–) terminal cable from the battery.

(b)

Connect the airbag sensor assembly connector.

(c)

Connect negative (–) terminal cable to the battery, and
wait at least for 2 seconds.

(d)

Turn the ignition switch to ON.

CHECK:
Check operation of the SRS warning light.

NO

Check terminal LA of airbag sensor assembly.
If normal, 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 simulation method to check.

DI–438

–

DIAGNOSTICS

SUPPLEMENTAL RESTRAINT SYSTEM

LEXUS RX300   (RM785E)

5

Is new AM2 fuse burnt out again?

NO

Using simulation method, reproduce malfunc-
tion symptoms (See page IN–22).

YES

Check harness between AM2 fuse and SRS
warning light.

H16261

Airbag Sensor 
Assembly

A28

19

P–B

8

11

1L

1E

Instrument Panel J/B

P–B

Tc

5F

5C

4

7

J/B No. 5

P–B

13

DLC3

D3

W–B

11

5B

5B

3

W–B

4

GC

IF

Tc

–

DIAGNOSTICS

SUPPLEMENTAL RESTRAINT SYSTEM

DI–439

LEXUS RX300   (RM785E)

Tc Terminal Circuit

CIRCUIT DESCRIPTION

By connecting terminals Tc and CG of the DLC3 the airbag sensor assembly is set in the DTC output mode.
The DTCs are displayed by blinking the SRS warning light.

WIRING DIAGRAM

DI6Q0–08