Subaru Legacy IV (2008 year). Manual - part 1018

AB(diag)-60

Diagnostic Chart with Trouble Code

AIRBAG SYSTEM (DIAGNOSTICS)

H: DTC 27 ODS COMMUNICATION ERROR

DTC DETECTING CONDITION:
• Communication to the occupant detection control module is faulty.
• Airbag rear harness circuit is open, shorted, shorted to ground or shorted to power supply.
• Occupant detection harness (seat harness) is faulty.
• Occupant detection system is faulty.
• Airbag control module is faulty.

Step

Check

Yes

No

1

CHECK POOR CONTACT IN CONNECTORS.
Check for poor contact of the connectors 
between the airbag control module and the 
occupant detection control module.

Is there poor contact?

Reconnect the 
connector. If defec-
tive is not 
improved, replace 
the airbag rear har-
ness along with the 
body harness or 
the occupant 
detection harness 
(seat harness).

Go to step 2.

2

CHECK AIRBAG HARNESS.
1) Turn the ignition switch to OFF, disconnect 
the battery ground cable, and wait for 20 sec-
onds or more.
2) Disconnect the connectors (AB6, AB17, 
AB18) from airbag control module.
3) Disconnect the connectors (AB59) and 
(AB53) under the passenger’s seat.
4) Connect the test harness AG connector 
(1AG) to the connectors (AB6, AB17, AB18).
5) Connect the connector (1AB) in the test har-
ness AB to the connector (AB53).
6) Measure the resistance between connector 
(6AG) in the test harness AG and connector 
(2AB) in the test harness AB.

Connector & terminal

(6AG) No. 9 — (2AB) No. 1:
(6AG) No. 11 — (2AB) No. 2:

Is the resistance less than 10 

:? Go to step 3.

Replace the airbag 
rear harness along 
with body harness.

3

CHECK AIRBAG HARNESS.
Measure the resistance between connector 
(3U) in the test harness U and chassis ground.

Connector & terminal

(6AG) No. 9 — Chassis ground:
(6AG) No. 9 — (6AG) No. 11:

Is the resistance less than 10 

:? Go to step 4.

Replace the airbag 
rear harness along 
with body harness.

4

CHECK AIRBAG HARNESS.
1) Turn the ignition switch to ON.
2) Measure the voltage between connector 
(2AB) in the test harness AB and chassis 
ground.

Connector & terminal

(2AB) No. 3 — Chassis ground:

Is the voltage 9 V or more?

Replace the occu-
pant detection har-
ness (seat 
harness). If defec-
tive is not 
improved, replace 
the occupant 
detection system 
(seat cushion & 
frame assembly), 
and then the airbag 
control module in 
this order.

Check the battery 
voltage and fuse. If 
there is no fault, 
replace the airbag 
rear harness along 
with body harness 
or replace the body 
harness.

AB(diag)-61

Diagnostic Chart with Trouble Code

AIRBAG SYSTEM (DIAGNOSTICS)

I:

DTC 29 ODS FAILURE

NOTE:
Refer to “Occupant Detection System” for details on DTC 29. <Ref. to OD(diag)-26, DTC 29 ODS FAILURE,
Diagnostic Procedure with Diagnostic Trouble Code (DTC).>

J: DTC 2A ODS CALIBRATION ERROR

NOTE:
Refer to “Occupant Detection System” for details on DTC 2A. <Ref. to OD(diag)-23, DTC 2A ODS CALIBRA-
TION ERROR, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>

K: DTC 2B ODS SYSTEM WRONG PARTS

NOTE:
Refer to “Occupant Detection System” for details on DTC 2B. <Ref. to OD(diag)-23, DTC 2B ODS SYSTEM
WRONG PARTS, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>

L: DTC 2C BELT TENSION SENSOR FAILURE

NOTE:
Refer to “Occupant Detection System” for details on DTC 2C. <Ref. to OD(diag)-24, DTC 2C BELT TENSION
SENSOR FAILURE, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>

M: DTC 33 FRONT SUB SENSOR RH FAILURE

DTC DETECTING CONDITION:
Front sub sensor (RH) is faulty.
If DTC 33 is displayed, the circuit within the front sub sensor (RH) is faulty.
Replace the front sub sensor (RH). <Ref. to AB-21, Front Sub Sensor.>

N: DTC 34 FRONT SUB SENSOR LH FAILURE

DTC DETECTING CONDITION:
Front sub sensor (LH) is faulty.
If DTC 34 is displayed, the circuit within the front sub sensor (LH) is faulty.
Replace the front sub sensor (LH). <Ref. to AB-21, Front Sub Sensor.>

O: DTC 37 BUCKLE SWITCH RH FAILURE

NOTE:
Refer to “Occupant Detection System” for details on DTC 37. <Ref. to OD(diag)-27, DTC 37 BUCKLE
SWITCH RH FAILURE, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>

AB(diag)-62

Diagnostic Chart with Trouble Code

AIRBAG SYSTEM (DIAGNOSTICS)

P: DTC 39 SEAT BELT WARNING FAILURE

DTC DETECTING CONDITION:
• Airbag control module is faulty.
• Body integrated unit is faulty.
• Harness circuits between body integrated unit and airbag control module are open, shorted or shorted to
ground.

CAUTION:
• Before diagnosing the airbag system, be sure to turn the ignition switch to OFF, disconnect the
ground cable from the battery, and wait 20 seconds or more 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 connectors of the driver’s
and passenger’s seats for safety.
• When inspecting the airbag rear harness, disconnect the side airbag module connector, curtain
airbag module connector and seat belt pretensioner connector for safety reasons.
WIRING DIAGRAM:

AB6

1 2

3 4

5 6 7 8 9 10

1 2 3 4 5 6

AB1

R50

R150

1 2 3

4 5 6 7

8 9 10

12 13 14 15

11

16

No.4

B90

R50

R150

8

11

4

7

AB6

15

5 6 7 8

2

1

9

4

3

10

24

22

23

25

27

26

28

11 12 13

14 15 16

17 18 19 20 21

i1

24

1
9

i84

25

2

10 11

26

3

12

27

4

13

28

14

29

15 16

30

17

31

18

32

19

33

20

5 6

21

34 35

23

22

7 8

10

8

i84

8

B36

i1

6

B31

AB1

7

23

17

2

13

OFF

ON

PASSENGER'S SEAT BELT
& AIRBAG WARNING LIGHT

AB-01768

7 8

18 19 20

21 22 23 24 25 26 27 28

1 2 3

   5   6   7   8

10

   9

4

11 12 13 14

16 17

15

29 30

IGNITION
SWITCH

B

A

TTER

Y

AIRBAG CONTROL MODULE

BODY 
INTEGRATED 
UNIT

AB(diag)-63

Diagnostic Chart with Trouble Code

AIRBAG SYSTEM (DIAGNOSTICS)

Step

Check

Yes

No

1

CHECK AIRBAG HARNESS.
1) Turn the ignition switch to OFF, disconnect 
the battery ground cable, and wait for 20 sec-
onds or more.
2) Disconnect the connectors (AB6, AB17, 
AB18) from airbag control module.
3) Connect the battery ground terminal and 
turn the ignition switch to ON.

Does the passenger’s seat belt 
warning light blink for 6 sec-
onds and go off?

Go to step 3.

Go to step 2.

2

CHECK AIRBAG HARNESS.
1) Turn the ignition switch to OFF.
2) Connect the test harness AG connector 
(1AG) to the connectors (AB6, AB17, AB18).
3) Measure the resistance between connector 
(2AG) in the test harness AG and chassis 
ground.

Connector & terminal

(2AG) No. 10 — Chassis ground:

Is the resistance 1 M

: or 

more?

Replace the body 
integrated unit.

Repair the bulk-
head harness. Or 
replace the airbag 
main harness 
along with body 
harness.

3

CHECK AIRBAG HARNESS.
1) Connect the connectors (7AG) and (8AG) in 
the test harness AG in the condition of step 2.
2) Turn the ignition switch to ON.

Does the passenger’s seat belt 
warning light blink for 6 sec-
onds, then repeatedly light and 
go off?

Replace the airbag 
control module. 
<Ref. to AB-20, 
Airbag Control 
Module.>

Go to step 4.

4

CHECK AIRBAG HARNESS.
1) Disconnect the connectors (7AG) and 
(8AG) in the test harness AG in the condition of 
step 3.
2) Measure the resistance between connector 
(2AG) in the test harness AG and connector 
(i84).

Connector & terminal

(2AG) No. 10 — (i84) No. 13:

Is the resistance less than 10 

:? Replace the body 

integrated unit.

Repair the bulk-
head harness. Or 
replace the airbag 
main harness 
along with body 
harness.