Subaru Legacy IV (2008 year). Service manual — part 1028

AB(diag)-100

Diagnostic Chart with Trouble Code

AIRBAG SYSTEM (DIAGNOSTICS)

AN:DTC E4 FRONT SENSOR BUS RH COMMUNICATION ERROR

DTC DETECTING CONDITION:
• Open or short circuit in harness of front sensor bus (RH).
• Front sub sensor (RH) is faulty.
• Airbag control module is faulty.

CAUTION:
• Before diagnosing the airbag system, be sure to turn the ignition switch to OFF, disconnect the
ground cable from 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 and seat belt
pretensioners of the driver’s and passenger’s seats for safety reasons.
WIRING DIAGRAM:

AB6

AB16

27

29

1

2

AB6

AB16

1 2

AB-02112

18 19 20

21 22 23 24 25 26 27 28

1 2 3 4

11 12 13 14

16 17

15

29 30

AIRBAG CONTROL MODULE

FRONT SUB SENSOR RH

10

8

7

6

5

9

AB(diag)-101

Diagnostic Chart with Trouble Code

AIRBAG SYSTEM (DIAGNOSTICS)

Step

Check

Yes

No

1

CHECK POOR CONTACT IN CONNECTORS.
Check for poor contact of the connectors (AB6,
AB16) between the airbag control module and
the front sub sensor (RH).

Is there poor contact?

Replace the airbag
main harness
along with body
harness.

Go to step 2.

2

CHECK AIRBAG MAIN HARNESS (FRONT
SENSOR BUS RH).
1) Turn the ignition switch to OFF, disconnect
the battery ground cable, and wait for 20 sec-
onds or more.
2) Remove the instrument panel lower cover
and disconnect the connectors (AB7) and
(AB2).
3) Remove the instrument panel side cover on
the passenger’s side and disconnect the con-
nectors (AB10) and (AB9).
4) Disconnect the connectors (AB17, AB6,
AB18) from airbag control module.
5) Connect the connector (1AG) in the test har-
ness AG to the connectors (AB17, AB6, AB18).
6) Disconnect the front sub sensor (RH), and
then connect the connector (1H) in the test har-
ness H to connector (AB16).
7) Measure the resistance between connector
(4AG) in the test harness AG and connector
(3H) in the test harness H.

Connector & terminal

(4AG) No. 14 — (3H) No. 5:
(4AG) No. 12 — (3H) No. 6:

Is the resistance less than 10

:? Go to step 3.

Replace the airbag
main harness
along with body
harness.

3

CHECK AIRBAG MAIN HARNESS (FRONT
SENSOR BUS RH).
Measure the resistance between connector
(4AG) in the test harness AG and chassis
ground, and the resistance between connector
(4AG) in the test harness AG and connector
(3H) in test harness H.

Connector & terminal

(4AG) No. 14 — Chassis ground:
(4AG) No. 12 — Chassis ground:

Is the resistance 1 M

: or

more?

Go to step 4.

Replace the airbag
main harness
along with body
harness.

4

CHECK AIRBAG CONTROL MODULE.
1) Connect all connectors.
2) Clear the memory.
3) Perform the Inspection Mode.
4) Read the DTC.

Is the same DTC displayed?

Replace the front
sub sensor (RH).
<Ref. to AB-21,
REMOVAL, Front
Sub Sensor.>
Replace the airbag
control module if
not operating nor-
mally even after
replacing the sen-
sor. <Ref. to AB-
20, REMOVAL, Air-
bag Control Mod-
ule.>

Go to step 5.

5

CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed?

Check DTC using
“List of Diagnostic
Trouble Code”.
<Ref. to AB(diag)-
38, LIST, List of
Diagnostic Trouble
Code (DTC).>

Finish the diagno-
sis.

AB(diag)-102

Diagnostic Chart with Trouble Code

AIRBAG SYSTEM (DIAGNOSTICS)

AO:DTC E6 FRONT SENSOR BUS LH COMMUNICATION ERROR

NOTE:
Refer to DTC E8 for details on DTC E6. <Ref. to AB(diag)-103, DTC E8 FRONT SENSOR BUS LH COM-
MUNICATION ERROR, Diagnostic Chart with Trouble Code.>

AP:DTC E7 FRONT SENSOR BUS LH COMMUNICATION ERROR

NOTE:
Refer to DTC E8 for details on DTC E7. <Ref. to AB(diag)-103, DTC E8 FRONT SENSOR BUS LH COM-
MUNICATION ERROR, Diagnostic Chart with Trouble Code.>

AB(diag)-103

Diagnostic Chart with Trouble Code

AIRBAG SYSTEM (DIAGNOSTICS)

AQ:DTC E8 FRONT SENSOR BUS LH COMMUNICATION ERROR

DTC DETECTING CONDITION:
• Open or short circuit in harness of front sensor bus (LH).
• Front sub sensor (LH) is faulty.
• Airbag control module is faulty.

CAUTION:
• Before diagnosing the airbag system, be sure to turn the ignition switch to OFF, disconnect the
ground cable from 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 and seat belt
pretensioners of the driver’s and passenger’s seats for safety reasons.
WIRING DIAGRAM:

Step

Check

Yes

No

1

CHECK POOR CONTACT IN CONNECTORS.
Check for poor contact of the connectors (AB6,
AB13) between the airbag control module and
the front sub sensor (LH).

Is there poor contact?

Replace the airbag
main harness
along with body
harness.

Go to step 2.

AB6

AB13

28

30

1

2

AB6

AB13

1 2

AB-02113

18 19 20

21 22 23 24 25 26 27 28

1 2 3 4

11 12 13 14

16 17

15

29 30

AIRBAG CONTROL MODULE

FRONT SUB SENSOR LH

10

8

7

6

5

9