Toyota Sequoia (2005). Manual - part 421

H01018

H23474

Airbag 
Sensor 
Assembly

DC

P/T Squib LH

–

DIAGNOSTICS

SUPPLEMENTAL RESTRAINT SYSTEM

DI–1479

1673

12

Check front seat outer belt LH (P/T squib LH).

PREPARATION:
(a)

Turn the ignition switch to the LOCK position.

(b)

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

(c)

From the step 10:
Disconnect the service wire from connector ”C”.

(d)

Connect the connector to the front seat outer belt LH.

(e)

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

CHECK:
(a)

Turn the ignition switch to the ON position, and wait for at
least 60 seconds.

(b)

Clear the DTCs stored in memory (see page 

DI–1147

).

(c)

Turn the ignition switch to the LOCK position.

(d)

Turn the ignition switch to the ON position, and wait for at
least 60 seconds.

(e)

Check the DTCs (see page 

DI–1147

).

OK:

DTC B1905, B1906, B1907 or B1908 is not output.

HINT:
Codes other than DTC B1905, B1906, B1907 and B1908 may
be output at this time, but they are not related to this check.

NG

Replace front seat outer belt LH
(see page 

BO–163

).

OK

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 (see page 

DI–1137

).

HINT:

Perform the simulation method by selecting the check mode with the hand–held tester (see page 

DI–1151

).

After selecting the check mode, perform the simulation method by wiggling each connector of the air-
bag system or driving the vehicle on a city or rough road (see page 

DI–1151

).

DI–1480

–

DIAGNOSTICS

SUPPLEMENTAL RESTRAINT SYSTEM

1674

DTC

Normal

Source Voltage Drop

CIRCUIT DESCRIPTION

The SRS is equipped with a voltage–increase circuit (DC–DC converter) in the airbag sensor assembly in
case the source voltage drops. 
When the battery voltage drops, the voltage–increase circuit (DC–DC converter) functions to increase the
voltage of the SRS to normal voltage. 
A malfunction in this circuit is displayed differently from other codes. The source voltage drop is indicated
when the SRS warning light comes on without showing any DTCs. 
A malfunction in this circuit is not recorded in the airbag sensor assembly. The SRS warning light automati-
cally goes off when the source voltage returns to normal.

DTC No.

Detection Item

(Normal)

Source voltage drop

DIDHS–01

H24000

Airbag Sensor 
Assembly

IG2

A20

B

Engine Room J/B

Instrument Panel J/B

Instrument Panel J/B

I18 
Ignition SW

21

1A

3

1J

7

1C

2

1C

3

AM2

IG2

B–R

6

5

IGN1

AM2

2C

1

2D

1

W–R

W–R

B

4

5

B

F10 
Fusible Link 
Block

E1

E2

A20

25

A20

26

W–B

W–B

1A

6

1F

9

1F

10

1A

8

W–B

W–B

A

A

J8
J/C

IE

Battery

–

DIAGNOSTICS

SUPPLEMENTAL RESTRAINT SYSTEM

DI–1481

1675

WIRING DIAGRAM

H23040

IG2

A20

DI–1482

–

DIAGNOSTICS

SUPPLEMENTAL RESTRAINT SYSTEM

1676

INSPECTION PROCEDURE

CAUTION:
Be sure to perform the following procedures before troubleshooting to avoid unexpected airbag de-
ployment.
(a)

Turn the ignition switch to the LOCK position.

(b)

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

(c)

Disconnect the connectors from the airbag sensor assembly.

(d)

Disconnect the connectors from the steering wheel pad.

(e)

Disconnect the connectors from the front passenger airbag assembly.

(f)

w/ Side and curtain shield airbag:
Disconnect the connectors from the side airbag assembly LH and RH.

(g)

w/ Side and curtain shield airbag:
Disconnect the connectors from the curtain shield airbag assembly LH and RH.

(h)

Disconnect the connectors from the front seat outer belt LH and RH.

1

Check battery.

CHECK:
Measure the voltage of the battery.
OK:

Voltage: 11 to 14 V

NG

Replace battery.

OK

2

Check source voltage (power source).

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

Turn the ignition switch to the ON position.

(b)

Measure the voltage according to the value(s) in the table
below.

OK:

Tester Connection

Condition

Specified Condition

A20–21 (IG2) – 

Body ground

Ignition switch ON

10 to 14 V

NG

Repair or replace wire harness (battery – airbag
sensor assembly).

OK