Subaru Legacy III (2000-2003 year). Manual — part 905

AB-46

AIRBAG SYSTEM (DIAGNOSTICS)

DIAGNOSTIC CHART WITH DIAGNOSTIC TROUBLE CODE (DTC)

I:

DTC 25

DIAGNOSIS:
• Airbag control module is faulty.
• Airbag main harness circuit is open.
• Fuse No. 6 (in joint box) is blown.
• Body harness circuit is open.

CAUTION:
• Before diagnosing the airbag system, be sure to turn the ignition switch OFF, disconnect the
ground cable from the battery, and wait more than 20 seconds before starting to work.
• Before replacing the airbag module, roll connector, control module, and sensor, reconnect each
part and confirm that the warning light operates properly.
• When inspecting the airbag main harness, disconnect the driver's airbag module and passenger's
airbag module connectors for safety reasons.
WIRING DIAGRAM:

AB-00296

5

11

AIRBAG CONTROL MODULE

AB6

B31

AB1

NO. 6

B

A

TTER

Y

IG SW

AB6

1 2 3

4 5 6

7 8 9 10 11 12 13 14 15 16 17

18 19 20 21 22 23 24 25 26 27 28

B31

1 2

3 4 5

6 7 8 9 10 11 12

AB1

1

2

3

4

5

6

7

8

9

10

11

12

AB-47

AIRBAG SYSTEM (DIAGNOSTICS)

DIAGNOSTIC CHART WITH DIAGNOSTIC TROUBLE CODE (DTC)

Step

Value

Yes

No

1

CHECK FUSE NO. 6 (IN JOINT BOX).
1) Confirm that the ignition switch is turned

OFF.

2) Remove No. 6 fuse (in joint box) and per-

form visual inspection.
Is fuse No. 6 blown?

Fuse No. 6 is not blown.

Go to step 2.

Replace fuse No.
6. If fuse No. 6 is
blown again,
repair the body
harness.

2

CHECK AIRBAG CONTROL MODULE.
1) Turn the ignition switch OFF, disconnect

the battery ground cable, and wait more
than 20 seconds.

2) Disconnect the connector (AB6) from air-

bag control module. <Ref. to AB-17, Airbag
Control Module.>

3) Connect the connector (1I) in test harness

I2 to connector (AB6).

4) Connect the battery ground cable, and turn

the ignition switch ON.

5) Measure the voltage between the connec-

tor (2I) in test harness I2 and the chassis
ground.

Connector & terminal

(2I) No. 6 (+) — Chassis ground (

−−−−

):

Does the measured value exceed the spec-
ified value?

10 V

Replace the airbag
control module.
<Ref. to AB-17,
Airbag Control
Module.>

Go to step 3.

3

CHECK AIRBAG MAIN HARNESS.
1) While checking control module, turn the

ignition switch OFF and disconnect the bat-
tery ground cable. Wait more than 20 sec-
onds before operation.

2) Disconnect the airbag connector (AB1)

from the body harness (B31).

3) Measure the voltage between the connec-

tor (B31) and the chassis ground.

Connector & terminal

(B31) No. 11 (+) — Chassis ground (

−−−−

):

Does the measured value exceed the spec-
ified value?

10 V

Replace the airbag
main harness.
<Ref. to AB-15,
Main Harness.>

Repair the body
harness.

AB-48

AIRBAG SYSTEM (DIAGNOSTICS)

DIAGNOSTIC CHART WITH DIAGNOSTIC TROUBLE CODE (DTC)

J: DTC 31

DIAGNOSIS:
• Front sub-sensor harness (RH) circuit is shorted.
• Front sub-sensor harness (RH) circuit is open.
• Front sub-sensor (RH) is faulty.
• Airbag control module is faulty.

CAUTION:
• Before diagnosing the airbag system, be sure to turn the ignition switch OFF, disconnect the
ground cable from the battery, and wait more than 20 seconds before starting to work.
• Before replacing the airbag module, roll connector, control module, and sensor, reconnect each
part and confirm that the warning light operates properly.
• When inspecting the airbag main harness, disconnect the driver's airbag module and passenger's
airbag module connectors for safety reasons.
WIRING DIAGRAM:

AB-00297

20

9

FRONT SUB SENSOR RH

2

1

1

2

AIRBAG CONTROL MODULE

AB6

AB14

AB15

AB16

AB15

AB16

1 2

AB6

1 2 3

4 5 6

7 8 9 10 11 12 13 14 15 16 17

18 19 20 21 22 23 24 25 26 27 28

2

1

AB-49

AIRBAG SYSTEM (DIAGNOSTICS)

DIAGNOSTIC CHART WITH DIAGNOSTIC TROUBLE CODE (DTC)

Step

Value

Yes

No

1

CHECK FRONT SUB-SENSOR (RH) AND
FRONT SUB-SENSOR HARNESS (RH).
1) Turn the ignition switch OFF, disconnect

the battery ground cable, and wait more
than 20 seconds.

2) Disconnect the connector (AB6) from the

airbag control module , and connect the
connector (1I) in test harness I2. <Ref. to
AB-17, Airbag Control Module.>

3) Measure the resistance of the connector

(3I) in test harness I2.

Connector & terminal

(3I) No. 2 — No. 4:

Is the measured value within the specified
range?

750

Ω

— 1 K

Ω

Go to step 2.

Go to step 3.

2

CHECK FRONT SUB-SENSOR (RH) AND
FRONT SUB-SENSOR HARNESS (RH).
Measure the resistance between connector
(3I) in test harness I2 and the chassis ground.

Connector & terminal

(3I) No. 2 — Chassis ground:
(3I) No. 4 — Chassis ground:

Does the measured value exceed the specified
value?

1 M

Ω

Replace

the

airbag

control module.
<Ref. to AB-17,
Airbag Control
Module.>

Go to step 3.

3

CHECK AIRBAG MAIN HARNESS AND
FRONT SUB-SENSOR HARNESS (RH).
1) Disconnect connector (AB16) from the

front sub-sensor. <Ref. to AB-20, Front
Sub Sensor.>

2) Connect connector (IH) in test harness H to

connector (AB16).

3) Measure the resistance between connector

(3I) in test harness I2 and connector (3H) in
test harness H.

Connector & terminal

(3I) No. 2 — (3H) No. 5:
(3I) No. 4 — (3H) No. 6:

Is the measured value less than the speci-
fied value?

10

Ω

Go to step 4.

Go to step 5.

4

CHECK AIRBAG MAIN HARNESS AND
FRONT SUB-SENSOR HARNESS (RH).
Measure the resistance between connector
(3I) in test harness I2 and the chassis ground.

Connector & terminal

(3I) No. 2 — Chassis ground:
(3I) No. 4 — Chassis ground:

Does the measured value exceed the specified
value?

1 M

Ω

Go to step 9.

Go to step 5.