Subaru Impreza 3 / Impreza WRX / Impreza WRX STI. Service manual — part 652

AB(diag)-147

Diagnostic Chart with Trouble Code

AIRBAG SYSTEM (DIAGNOSTICS)

BP:DTC E3 FRONT SENSOR BUS RH COMMUNICATION ERROR

NOTE:

Refer to DTC A1 for DTC E3. <Ref. to AB(diag)-145, DTC A1 FRONT SENSOR BUS COMMUNICATION

ERROR, Diagnostic Chart with Trouble Code.>

BQ:DTC E4 FRONT SENSOR BUS RH COMMUNICATION ERROR

NOTE:

Refer to DTC A1 for DTC E4. <Ref. to AB(diag)-145, DTC A1 FRONT SENSOR BUS COMMUNICATION

ERROR, Diagnostic Chart with Trouble Code.>

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) terminals in the test harness AG.

Connector & terminal

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

Is the resistance 1 MΩ or
more?

Go to step

Replace the airbag
main harness
along with body
harness.

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 (LH)
and front sub sen-
sor (RH). <Ref. to
AB-22, REMOVAL,
Front Sub Sen-
sor.> Replace the
airbag control
module if not oper-
ating normally
even after replac-
ing the sensor.
<Ref. to AB-21,
REMOVAL, Airbag
Control Module.>

Go to step

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

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

Finish the diagno-
sis.

Step

Check

Yes

AB(diag)-148

Diagnostic Chart with Trouble Code

AIRBAG SYSTEM (DIAGNOSTICS)

BR:DTC E7 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 60 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

pretensioner connectors of the driver’s and passenger’s seats for safety reasons.

WIRING DIAGRAM:

Airbag system <Ref. to WI-82, WIRING DIAGRAM, Airbag System.>

Step

Check

Yes

CHECK POOR CONTACT OF CONNEC-
TORS.
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

AB-02466

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 29 30

1 2

AB13

AB6

AIRBAG CM

FRONT SUB SENSOR LH

AB(diag)-149

Diagnostic Chart with Trouble Code

AIRBAG SYSTEM (DIAGNOSTICS)

CHECK AIRBAG MAIN HARNESS (FRONT
SENSOR BUS LH).
1) Turn the ignition switch to OFF, disconnect
the battery ground cable, and wait for 60 sec-
onds or more.
2) Remove the instrument panel lower cover
and column cover, and disconnect the connec-
tors (AB7) and (AB2).
3) Remove the console front panel and discon-
nect the connector (AB9).
4) Disconnect the connectors (AB6, AB17,
AB18) from airbag control module.
5) Connect the connector (1AH) in the test har-
ness AH to the connectors (AB6, AB17, AB18).
6) Connect the connector (2AH) in the test har-
ness AH and the connector (1AG) in the test
harness AG.
7) Disconnect the connector (AB13) from the
front sub sensor (LH), and then connect the
connector (1H) in the test harness H to connec-
tor (AB13).
8) Measure the resistance between connector
(4AG) in the test harness AG and connector
(3H) in the test harness H.

Connector & terminal

(4AG) No. 7 — (3H) No. 5:
(4AG) No. 9 — (3H) No. 6:

Is the resistance less than 10

Ω?

Go to step

Replace the airbag
main harness
along with body
harness.

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

Connector & terminal

(4AG) No. 7 — Chassis ground:
(4AG) No. 9 — Chassis ground:
(4AG) No. 7 — (4AG) No. 9:

Is the resistance 1 MΩ or
more?

Go to step

Replace the airbag
main harness
along with body
harness.

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 (LH).
<Ref. to AB-22,
REMOVAL, Front
Sub Sensor.>
Replace the airbag
control module if
not operating nor-
mally even after
replacing the sen-
sor. <Ref. to AB-
21, REMOVAL, Air-
bag Control Mod-
ule.>

Go to step

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

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

Finish the diagno-
sis.