Subaru Legacy (2005 year). Manual — part 910

AB(diag)-77

AIRBAG SYSTEM (DIAGNOSTICS)

Diagnostic Chart with Trouble Code

1. MODEL WITH CURTAIN AIRBAG OR LAP SEAT BELT PRETENSIONER

Step

Check

Yes

No

1

CHECK AIRBAG REAR HARNESS (SIDE
AIRBAG SENSOR HARNESS LH).
1) Turn the ignition switch OFF, disconnect the
battery ground cable, and wait more than 20
seconds.
2) Disconnect the connector (AB21) from seat
belt pretensioner (LH).
3) Disconnect the connector (AB31) from cur-
tain airbag module (LH).
4) Disconnect the connector (AB20) from
(AB19).
5) Disconnect the connector (AB17) from air-
bag control module.
6) Connect the connector (1U) in the test har-
ness U to connector (AB17).
7) Disconnect the connector (AB23) from side
airbag sensor (LH), and connect the connector
(2V) in test harness V to connector (AB23).
8) Measure the resistance between connector
(4U) in the test harness U and connector (3V)
in the test harness V.

Connector & terminal

(4U) No. 3 — (3V) No. 4:
(4U) No. 1 — (3V) No. 5:
(4U) No. 2 — (3V) No. 1:
(4U) No. 4 — (3V) No. 2:

Is the resistance less than 10
Ω?

Go to step 2.

Replace the airbag
rear harness with
body harness.

2

CHECK AIRBAG REAR HARNESS (SIDE
AIRBAG SENSOR HARNESS LH).
Measure the resistance between connector
(4U) in the test harness U and chassis ground.

Connector & terminal

(4U) No. 3 — Chassis ground:
(4U) No. 1 — Chassis ground:
(4U) No. 2 — Chassis ground:
(4U) No. 4 — Chassis ground:

Is the resistance more than 1
M

Ω?

Replace the side
airbag sensor
(LH). <Ref. to AB-
23, Side Airbag
Sensor.> When
the sensor is not
OK though the
sensor is replaced,
replace the airbag
control module.
<Ref. to AB-22,
Airbag Control
Module.>

Replace the airbag
rear harness with
body harness.

AB(diag)-78

AIRBAG SYSTEM (DIAGNOSTICS)

Diagnostic Chart with Trouble Code

2. MODEL WITHOUT CURTAIN AIRBAG

Step

Check

Yes

No

1

CHECK AIRBAG REAR HARNESS (SIDE
AIRBAG SENSOR HARNESS LH).
1) Turn the ignition switch OFF, disconnect the
battery ground cable, and wait more than 20
seconds.
2) Disconnect the connector (AB21) from seat
belt pretensioner (LH).
3) Disconnect the connector (AB31) from cur-
tain airbag module (LH).
4) Disconnect the connector (AB20) from
(AB19).
5) Disconnect the connector (AB17) from air-
bag control module.
6) Connect the connector (1R) in the test har-
ness R to connector (AB17).
7) Disconnect the connector (AB23) from side
airbag sensor (LH), and connect the connector
(2V) in test harness V to connector (AB23).
8) Measure the resistance between connector
(4R) in the test harness R and connector (3V)
in the test harness V.

Connector & terminal

(4R) No. 3 — (3V) No. 4:
(4R) No. 1 — (3V) No. 5:
(4R) No. 2 — (3V) No. 1:
(4R) No. 4 — (3V) No. 2:

Is the resistance less than 10
Ω?

Go to step 2.

Replace the airbag
rear harness with
body harness.

2

CHECK AIRBAG REAR HARNESS (SIDE
AIRBAG SENSOR HARNESS LH).
Measure the resistance between connector
(4R) in the test harness R and chassis ground.

Connector & terminal

(4R) No. 3 — Chassis ground:
(4R) No. 1 — Chassis ground:
(4R) No. 2 — Chassis ground:
(4R) No. 4 — Chassis ground:

Is the resistance more than 1
M

Ω?

Replace the side
airbag sensor
(LH). <Ref. to AB-
23, Side Airbag
Sensor.> When
the sensor is not
OK though the
sensor is replaced,
replace the airbag
control module.
<Ref. to AB-22,
Airbag Control
Module.>

Replace the airbag
rear harness with
body harness.

AB(diag)-79

AIRBAG SYSTEM (DIAGNOSTICS)

Diagnostic Chart with Trouble Code

T: DTC 53 SIDE AIRBAG SENSOR RH FAILURE

DTC DETECTING CONDITION:
Side airbag sensor (RH) is faulty.
If DTC 53 is displayed, the circuit within the side airbag sensor (RH) is faulty. Replace the side airbag sensor
(RH). <Ref. to AB-23, Side Airbag Sensor.>

U: DTC 54 SIDE AIRBAG SENSOR LH FAILURE

DTC DETECTING CONDITION:
Side airbag sensor (LH) is faulty.
If DTC 54 is displayed, the circuit within the side airbag sensor (LH) is faulty. Replace the side airbag sensor
(LH). <Ref. to AB-23, Side Airbag Sensor.>

V: DTC 55 SIDE CURTAIN AIRBAG FIRING OUTPUT

This code is displayed when the side airbag module and curtain airbag module are deployed.
Once this code is displayed, the memory cannot be erased. Replace the following parts.
• Airbag control module <Ref. to AB-22, Airbag Control Module.>
• Front seat with side airbag module (Operating side) <Ref. to SE-7, Front Seat.>
• Side airbag sensor (Operating side) <Ref. to AB-23, Side Airbag Sensor.>
• Curtain airbag module (Operating side) <Ref. to AB-20, Curtain Airbag Module.>
• Curtain airbag sensor (Operating side) <Ref. to AB-24, Curtain Airbag Sensor.>

AB(diag)-80

AIRBAG SYSTEM (DIAGNOSTICS)

Diagnostic Chart with Trouble Code

W: DTC 56 CURTAIN AIRBAG SENSOR RH FAILURE

DTC DETECTING CONDITION:
• Curtain airbag sensor (RH) is faulty.
• Curtain airbag harness (RH) circuit 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.
• When inspecting the airbag rear harness, disconnect the side airbag module connector, curtain
airbag module connector, seat belt pretensioner connector and lap seat belt pretensioner connector
for safety reasons.
WIRING DIAGRAM:

AB-01258

AB18

AB33

AB40

1

2

6

5

AB34

20

19

4

18

3

4

1

2

AB18

AB33

1 2

AIRBAG CONTROL MODULE

CURTAIN AIRBAG

MODULE RH

CURTAIN AIRBAG

SENSOR RH

7 8 9 10 11 12

13 14 15 16 17 18 19

5 6

20

1 2

3 4

AB34

1 2 3 4