Subaru Legacy IV (2008 year). Manual - part 1040

OD(diag)-25

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

OCCUPANT DETECTION SYSTEM (DIAGNOSTICS)

D: DTC 27 ODS COMMUNICATION ERROR

Perform the diagnosis following diagnostic procedures for the airbag system. <Ref. to AB(diag)-60, DTC 27
ODS COMMUNICATION ERROR, Diagnostic Chart with Trouble Code.>

Step

Check

Yes

No

1

CHECK POOR CONTACT OF CONNEC-
TORS.
Check for poor contact of the connectors 
between the occupant detection control module 
and belt tension sensor.

Is there poor contact?

Reconnect the 
connector. If the 
fault is not fixed, 
replace the airbag 
harness.

Go to step 2.

2

CHECK BELT TENSION SENSOR.
1) Turn the ignition switch to OFF, disconnect 
the battery ground cable, and wait for 20 sec-
onds or more.
2) Disconnect the belt tension sensor connec-
tor (AB56) from the airbag harness.
3) Connect the test harness AC to the connec-
tor (AB56).
4) Connect the battery ground terminal and 
turn the ignition switch to ON.

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

Replace the seat 
belt outer. <Ref. to 
SB-18, OUTER 
SEAT BELT 
ASSEMBLY, 
REMOVAL, Front 
Seat Belt.>

Go to step 3.

3

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 test harness AC from the 
belt tension sensor connector (AB56).
3) Connect the test harness AD (1AD) to the 
connector (AB56).
4) Disconnect the airbag harness connector 
(AB53), and connect connector (1AB) of test 
harness AB.
5) Measure the resistance between test har-
ness terminals.

Connector & terminal

(2AB) No. 5 — (2AD) No. 1:
(2AB) No. 4 — (2AD) No. 3:
(2AB) No. 6 — (2AD) No. 2:

Is the resistance less than 10 

:? Go to step 4.

Replace the airbag 
harness along with 
chassis harness.

4

CHECK AIRBAG HARNESS.
Measure the resistance between test harness 
terminals, and between test harness terminal 
and chassis ground.

Connector & terminal

(2AB) No. 4 — (2AD) No. 1:
(2AB) No. 4 — (2AD) No. 2:
(2AB) No. 4 — Chassis ground:
(2AB) No. 5 — (2AD) No. 2:
(2AB) No. 5 — Chassis ground:

Is the resistance 1 M

: or 

more?

Go to step 5.

Replace the airbag 
harness along with 
chassis harness.

5

CHECK AIRBAG HARNESS.
1) Connect the battery ground terminal and 
turn the ignition switch to ON.
2) Measure the voltage between test harness 
and chassis ground.

Connector & terminal

(2AD) No. 1 — chassis ground:
(2AD) No. 3 — chassis ground:

Is the voltage 1 V or less?

Replace the airbag 
harness along with 
chassis harness.

Check the seat 
harness, and if any 
fault is found, 
replace the seat 
harness. If no fault 
is found in the seat 
harness, replace 
the seat cushion 
frame assembly. 
<Ref. to SE-15, 
PASSENGER’S 
SEAT, DISASSEM-
BLY, Front Seat.>

OD(diag)-26

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

OCCUPANT DETECTION SYSTEM (DIAGNOSTICS)

E: DTC 29 ODS FAILURE

DTC DETECTING CONDITION:
• Occupant detection sensor is faulty.
• Occupant detection control module is faulty.
• Occupant detection harness is faulty.
• Rear airbag harness is faulty.
• Fuse No. 25 (in joint box) is blown.

Step

Check

Yes

No

1

CHECK POOR CONTACT OF CONNEC-
TORS.
Check for poor contact of the connectors 
between the occupant detection control module 
and airbag control module.

Is there poor contact?

Reconnect the 
connector. If the 
fault is not fixed, 
replace the airbag 
harness.

Go to step 2.

2

CHECK DIAGNOSTIC CODE.
Read diagnostic trouble code (DTC) for the air-
bag system.

Is “2C Belt Tension Sensor fail-
ure or 37 Buckle Switch failure” 
displayed in the diagnostics 
code?

Perform the diag-
nosis according to 
each DTC.

Check the seat 
harness, and if any 
fault is found, 
replace the seat 
harness. If the fault 
is not fixed, replace 
the occupant 
detection system. 
<Ref. to SE-15, 
PASSENGER’S 
SEAT, DISASSEM-
BLY, Front Seat.>

OD(diag)-27

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

OCCUPANT DETECTION SYSTEM (DIAGNOSTICS)

F: DTC 37 BUCKLE SWITCH RH FAILURE

DTC DETECTING CONDITION:
• Passenger’s buckle switch circuit is open, shorted or shorted to ground.
• Seat harness circuit is open, shorted or shorted to ground.
• Occupant detection control module is faulty.
WIRING DIAGRAM:

Step

Check

Yes

No

1

CHECK POOR CONTACT OF CONNEC-
TORS.
Check for poor contact of the connectors 
between the occupant detection control module 
and buckle switch.

Is there poor contact?

Reconnect the 
connector. If the 
fault is not fixed, 
replace the airbag 
harness.

Go to step 2.

2

CHECK BUCKLE SWITCH.
1) Turn the ignition switch to OFF, disconnect 
the battery ground terminal, and wait for 20 sec-
onds.
2) Disconnect the buckle switch connector 
(AB60).
3) Connect the test harness AE1 and test har-
ness connector Y to the buckle switch connec-
tor (AB60).
4) Connect the battery ground terminal and 
turn the ignition switch to ON.

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

Replace the buckle 
switch. <Ref. to 
SB-18, INNER 
SEAT BELT 
ASSEMBLY, 
REMOVAL, Front 
Seat Belt.>

Check the seat 
harness, and if any 
fault is found, 
replace the seat 
harness. If the fault 
is not fixed, replace 
the occupant 
detection system.

AB60

1 2

1

2

AB60

OD-00064

1

2

AB43

AB43

1 2 3

10 11 12

4 5 6

13 14 15

7 8 9

16 17 18

FRONT 

SEAT BELT 
SWITCH RH

OCCUPANT DETECTION

 CONTROL MODULE

OD(diag)-28

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

OCCUPANT DETECTION SYSTEM (DIAGNOSTICS)