Subaru Impreza 3 / Impreza WRX / Impreza WRX STI. Service manual — part 455

6MT(diag)-31

Diagnostic Procedure without Diagnostic Trouble Code (DTC)

MANUAL TRANSMISSION AND DIFFERENTIAL (DIAGNOSTICS)

5

CHECK HARNESS BETWEEN BODY INTE-
GRATED UNIT AND PARKING BRAKE
SWITCH.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from body inte-
grated unit.
3) Check for open circuit, short circuit to bat-
tery and short circuit to ground between the
body integrated unit connector and parking
brake switch connector.

Connector & terminal

(B281) No. 15 — (R4) No. 1:

Is the harness normal?

Go to step

6.

Repair or replace
the harness.

6

CHECK PARKING BRAKE SWITCH.
Measure the resistance between parking brake
switch terminals.

Is the resistance less than 10 Ω
when the parking brake lever is
pulled?
Is the resistance 1 MΩ or more
when the parking brake lever is
lowered?

Replace the body
integrated unit.

Replace the park-
ing brake switch.

7

CHECK DTC.
Check DTC of body integrated unit.

Is the DTC related to CAN dis-
played?

Perform the diag-
nosis according to
DTC.

Check the poor
contact of DCCD
system.

Step

Check

Yes

No

6MT(diag)-32

Diagnostic Procedure without Diagnostic Trouble Code (DTC)

MANUAL TRANSMISSION AND DIFFERENTIAL (DIAGNOSTICS)

C: CHECK DCCD MULTI SELECT SWITCH

DIAGNOSIS:

Input signal of DCCD multi select switch is open or shorted.

TROUBLE SYMPTOM:

• Does not enter the manual mode or auto mode when the mode change switch is pressed.

• Mode does not change in AUTO mode.

• Initial torque can not be changed in manual mode.
NOTE:

Other switch input can not be received if either mode change switch or C.DIFF +/– switch is stuck ON.

WIRING DIAGRAM:

Drivers control center differential control system <Ref. to WI-72, Driver’s Control Center Differential Control

System.>

Step

Check

Yes

No

1

CHECK DCCD CONTROL MODULE.
1) Display the current data «AUTO/MANUAL
Mode Switch» of DCCD control module, using
Subaru Select Monitor.
2) Press the manual mode change switch.

Does the data change from
OFF/ON?

Go to step

2.

Go to step

4.

2

CHECK DCCD CONTROL MODULE.
1) Display the current data «Up Switch» of
DCCD control module, using Subaru Select
Monitor.
2) Push the multi select switch toward plus.

Does the data change from
OFF/ON?

Go to step

3.

Go to step

5.

3

CHECK DCCD CONTROL MODULE.
1) Display the current data «Down Switch» of
DCCD control module, using Subaru Select
Monitor.
2) Push the multi select switch toward minus.

Does the data change from
OFF/ON?

The switch circuit
is normal.

Go to step

6.

AD10

32

31

30

29

28

27

26

25

24

23

22

21

20

19

18

17

16

15

14

13

12

11

10

2

10

9

8

7

6

4

3

2

5

1

R33

15

4

1

3

1

9

3

1

B98

R2

R33

4

2

2

6

B380

16

15

10

1

20

9

1

8

1

7

1

4

1

3

1

2

1

1

1

9

6 7 8

5

2 3 4

B98

9

8

7

6

5

4

3

2

1

B380

MT-02941

E

DCCD CM

MULTI SELECT SWITCH (DCCD)

A

UT

O/

MANU

AL

6MT(diag)-33

Diagnostic Procedure without Diagnostic Trouble Code (DTC)

MANUAL TRANSMISSION AND DIFFERENTIAL (DIAGNOSTICS)

4

CHECK MODE CHANGE SWITCH.
1) Disconnect the multi select switch connec-
tor.
2) Press the mode change switch.
3) Using the tester, measure the resistance
between terminals.

Connector & terminal

(AD10) No. 1 — No. 9:

Is the resistance less than 1 Ω? Go to step

7.

Replace the multi
select switch.
<Ref. to FU(STI)-
58, SI-DRIVE
(SUBARU Intelli-
gent Drive) Selec-
tor.>

5

CHECK MULTI SELECT SWITCH.
1) Push the multi select switch toward plus.
2) Using the tester, measure the resistance
between terminals.

Connector & terminal

(AD10) No. 2 — No. 9:

Is the resistance less than 1 Ω? Go to step

7.

Replace the multi
select switch.
<Ref. to FU(STI)-
58, SI-DRIVE
(SUBARU Intelli-
gent Drive) Selec-
tor.>

6

CHECK MULTI SELECT SWITCH.
1) Push the multi select switch toward minus.
2) Using the tester, measure the resistance
between terminals.

Connector & terminal

(AD10) No. 3 — No. 9:

Is the resistance less than 1 Ω? Go to step

7.

Replace the multi
select switch.
<Ref. to FU(STI)-
58, SI-DRIVE
(SUBARU Intelli-
gent Drive) Selec-
tor.>

7

CHECK HARNESS.
Use a tester to measure the resistance between
the multi select switch harness connector and
chassis ground.

Connector & terminal

(R33) No. 9 — Chassis ground:

Is the resistance less than 1 Ω? Go to step

8.

Repair or replace
the ground circuit.

8

CHECK HARNESS.
1) Disconnect the connector from DCCD con-
trol module.
2) Use a tester to measure the resistance
between the DCCD control module and the
multi select switch.

Connector & terminal

(R33) No. 1 — (B380) No. 6:
(R33) No. 2 — (B380) No. 22:
(R33) No. 3 — (B380) No. 4:

Is the resistance less than 1 Ω? Go to step

9.

Repair or replace
the open circuit of
the harness.

9

CHECK HARNESS.
Using the tester, measure the resistance
between terminals.

Connector & terminal

(R33) No. 1 — (R33) No. 2:
(R33) No. 1 — (R33) No. 3:
(R33) No. 3 — (R33) No. 2:

Is the resistance 1 MΩ or
more?

Go to step

10.

Repair or replace
the short of har-
ness.

10

CHECK HARNESS.
Using the tester, measure the resistance
between terminals.

Connector & terminal

(R33) No. 1 — Chassis ground:
(R33) No. 2 — Chassis ground:
(R33) No. 3 — Chassis ground:

Is the resistance 1 MΩ or
more?

Check the poor
contact.

Repair or replace
the short of har-
ness.

Step

Check

Yes

No

6MT(diag)-34

Diagnostics with Phenomenon

MANUAL TRANSMISSION AND DIFFERENTIAL (DIAGNOSTICS)

15.Diagnostics with Phenomenon

A: INSPECTION

Symptoms

Faulty parts

A tight corner braking symptom occurs.

• VDCCM&H/U
• ABS wheel speed sensor
• Yaw rate & G sensor
• Steering angle sensor
• CAN communication signal
• Center differential
• C.DIFF +/– switch
• Mode change switch
• Tire/Wheel
• DCCD control module
• ECM
• Body integrated unit

An oversteer tendency will become apparent.

• Throttle position sensor
• ECM
• C.DIFF +/– switch
• Mode change switch
• Tire/Wheel
• DCCD control module
• Center differential
• DCCD relay
• Rear differential oil temperature switch
• Neutral position switch
• Steering angle sensor
• VDCCM&H/U
• CAN communication signal
• Body integrated unit
• Yaw rate & G sensor

A tendency to understeer occurs during high speed cornering.

• VDCCM&H/U
• ABS wheel speed sensor
• CAN communication signal
• Throttle position sensor
• Yaw rate & G sensor
• Center differential
• ECM
• Engine speed signal
• Neutral position switch
• Steering angle sensor
• Body integrated unit

Torque characteristics of the center differential do not change.

• C.DIFF +/– switch
• DCCD relay
• Center differential
• DCCD control module

DCCD indicator does not operate. (is not displayed)

• Combination meter
• DCCD control module

DCCD indicator does not operate even when the C.DIFF +/–
switch is operated. (Displayed but does not change. or, the dis-
play blinks.)

• C.DIFF +/– switch
• Combination meter
• DCCD control module

DCCD AUTO mode does not operate even when the C.DIFF +/–
switch is operated. (Displayed but does not change.)

• Mode change switch
• Combination meter
• DCCD control module
• Body integrated unit
• CAN communication signal