Subaru Legacy (2005 year). Service manual — part 902

AB(diag)-45

AIRBAG SYSTEM (DIAGNOSTICS)

Diagnostic Chart with Trouble Code

B: DTC 12 PASSENGER’S AIRBAG FAILURE

DTC DETECTING CONDITION:
• Airbag main harness circuit is open, shorted or shorted to ground.
• Airbag module harness (Passenger’s side) circuit is open, shorted or shorted to ground.
• Passenger’s airbag module 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 battery, and wait more than 20 seconds before starting to work.
• When replacing the airbag module, seat belt pretensioner, roll connector, control module and sen-
sor, reconnect each part and check that the warning light operates properly.
• When inspecting the airbag main harness, disconnect the airbag module connector of the driver’s
and passenger’s seats for safety reasons.
WIRING DIAGRAM:

AB-01257

AB6

AIRBAG MODULE
(PASSENGER SIDE)

AB9

AB9

AB10

11

10

3

4

7

8

1

2

AIRBAG CONTROL MODULE

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

1 2 3 4

AB(diag)-46

AIRBAG SYSTEM (DIAGNOSTICS)

Diagnostic Chart with Trouble Code

Step

Check

Yes

No

1

CHECK PASSENGER’S AIRBAG MODULE.
1) Turn the ignition switch OFF, disconnect the
battery ground cable, and wait more than 20
seconds.
2) Remove the instrument panel side cover on
the passenger’s side.
3) Disconnect the connector (AB10) from
(AB9).
4) Connect the connector (1P) in the test har-
ness P to connector (AB9).
5) Connect the airbag resistor to connectors
(2P) and (3P) in the test harness P.
6) Connect the battery ground cable and turn
the ignition switch to ON.

Does the airbag warning light
illuminate for 6 seconds and go
off?

Replace the pas-
senger’s airbag
module. <Ref. to
AB-17, Passen-
ger’s Airbag Mod-
ule.>

Go to step 2.

2

CHECK AIRBAG MAIN HARNESS (PASSEN-
GER’S AIRBAG HARNESS).
1) Turn the ignition switch OFF, disconnect the
battery ground cable, and wait more than 20
seconds.
2) Disconnect the airbag resistor from con-
nectors (2P) and (3P) in the test harness P.
3) Remove the instrument panel lower cover
and disconnect the connector (AB7) from
(AB2).
4) Disconnect the connector (AB6) from air-
bag control module, and connect the connector
(1U) in the test harness U.
5) Measure the resistance between connector
(2U) in the test harness U and connectors (2P)
and (3P) in the test harness P.

Connector & terminal

(2U) No. 3 — (2P) No. 1:
(2U) No. 5 — (2P) No. 2:
(2U) No. 9 — (3P) No. 3:
(2U) No. 13 — (3P) No. 4:

Is the resistance less than 10
Ω?

Go to step 3.

Replace the airbag
main harness with
body harness.

3

CHECK AIRBAG MAIN HARNESS (PASSEN-
GER’S AIRBAG HARNESS).
Measure the resistance between connectors
(2U) in the test harness U, and between con-
nector (2U) and chassis ground.

Connector & terminal

(2U) No. 3 — (2U) No. 5:
(2U) No. 3 — Chassis ground:
(2U) No. 5 — Chassis ground:
(2U) No. 9 — (2U) No. 13:
(2U) No. 9 — Chassis ground:
(2U) No. 13 — Chassis ground:

Is the resistance more than 1
M

Ω?

Replace the airbag
control module.
<Ref. to AB-22,
Airbag Control
Module.>

Replace the airbag
main harness with
body harness.

AB(diag)-47

AIRBAG SYSTEM (DIAGNOSTICS)

Diagnostic Chart with Trouble Code

C: DTC 15 DRIVER’S AIRBAG FAILURE

DTC DETECTING CONDITION:
• Airbag main harness (Driver’s side) circuit is shorted to power supply.
• Airbag module harness (Driver’s side) circuit is shorted to power supply.
• Roll connector is shorted to power supply.
• Driver’s airbag module 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 battery, and wait more than 20 seconds before starting to work.
• When replacing the airbag module, seat belt pretensioner, roll connector, control module and sen-
sor, reconnect each part and check that the warning light operates properly.
• When inspecting the airbag main harness, disconnect the airbag module connector of the driver’s
and passenger’s seats for safety reasons.
WIRING DIAGRAM:

16

17

13

14

AB6

AB2

AB2

AB7

1

2

3

4

AB6

AB38

1

2

1

2

2

1

AB38

AIRBAG CONTROL MODULE

STEERING
ROLL CONNECTOR

AIRBAG MODULE

(DRIVER SIDE)

AB37

1 2 3 4

2

1

AB37

AB-01256

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

AB(diag)-48

AIRBAG SYSTEM (DIAGNOSTICS)

Diagnostic Chart with Trouble Code

Step

Check

Yes

No

1

CHECK DRIVER’S AIRBAG MODULE.
1) Turn the ignition switch OFF, disconnect the
battery ground cable, and wait more than 20
seconds.
2) Remove the driver’s airbag module.
3) Connect the connector (AB38) to the con-
nector (1N) in the test harness N.
4) Connect the airbag resistor to connector
(2N) in the test harness N.
5) Connect the connector (1Q) in the test har-
ness Q to connector (AB37).
6) Connect the airbag resistor to connector
(2Q) in the test harness Q.
7) Connect the battery ground cable and turn
the ignition switch to ON.

Does the airbag warning light
illuminate for 6 seconds and go
off?

Replace the
driver’s airbag
module. <Ref. to
AB-16, Driver’s
Airbag Module.>

Go to step 2.

2

CHECK ROLL CONNECTOR.
1) Turn the ignition switch OFF, disconnect the
battery ground cable, and wait more than 20
seconds.
2) Disconnect the test harness N from con-
nector (AB38).
3) Disconnect the test harness Q from con-
nector (AB37).
4) Remove the instrument panel lower cover
and disconnect the connector (AB7) from
(AB2).
5) Connect the connector (1P) in the test har-
ness P to connector (AB2).
6) Connect the airbag resistor to connectors
(2P) and (3P) in the test harness P.
7) Connect the battery ground cable and turn
the ignition switch to ON.

Does the airbag warning light
illuminate for 6 seconds and go
off?

Replace the roll
connector. <Ref. to
AB-25, Roll Con-
nector.>

Go to step 3.

3

CHECK AIRBAG MAIN HARNESS (DRIV-
ER’S AIRBAG HARNESS).
1) Turn the ignition switch OFF, disconnect the
battery ground cable, and wait more than 20
seconds.
2) Disconnect the airbag resistor from con-
nectors (2P) and (3P) in the test harness P.
3) Remove the instrument panel side cover on
passenger’s side and disconnect the connec-
tors (AB10) and (AB9).
4) Disconnect the connector (AB6) from air-
bag control module, and connect the connector
(1U) in the test harness U.
5) Connect the battery ground cable and turn
the ignition switch to ON. (engine OFF)
6) Measure the resistance between connector
(2U) in the test harness U and chassis ground.

Connector & terminal

(2U) No. 4 (+) — Chassis ground (

−

):

(2U) No. 2 (+) — Chassis ground (

−

):

(2U) No. 8 (+) — Chassis ground (

−

):

(2U) No. 12 (+) — Chassis ground (

−

):

Is the voltage less than 1 V?

Replace the airbag
control module.
<Ref. to AB-22,
Airbag Control
Module.>

Replace the airbag
main harness with
body harness.