Subaru Impreza 3 / Impreza WRX / Impreza WRX STI. Manual — part 454

6MT(diag)-27

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

MANUAL TRANSMISSION AND DIFFERENTIAL (DIAGNOSTICS)

12

CHECK DCCD RELAY.
Connect the battery positive lead to terminal
No. 27 and the negative lead to terminal No. 28,
then measure the resistance between DCCD
relay terminals.

Connector & terminal

(B220) No. 25 — No. 26:

Is the resistance less than 1 Ω? Go to step

13.

Replace the DCCD
relay.

13

CHECK DCCD CONTROL MODULE RELAY
DRIVE CIRCUIT.
1) Connect all connectors.
2) Turn the ignition switch to ON.
3) Measure the voltage between DCCD con-
trol module and chassis ground.

Connector & terminal

(B380) No. 7 (+) — Chassis ground (–):

Is the voltage less than 1 V?

Go to step

14.

Go to step

17.

14

CHECK IGNITION POWER SUPPLY CIRCUIT
OF DCCD CONTROL MODULE.
Measure the voltage between DCCD control
module and chassis ground.

Connector & terminal

(B380) No. 13 (+) — Chassis ground (–):
(B380) No. 14 (+) — Chassis ground (–):

Is the voltage 8 V or more?

Go to step

15.

Go to step

17.

15

CHECK CENTER DIFFERENTIAL.
1) Turn the ignition switch to OFF.
2) Connect the Subaru Select Monitor to data
link connector.
3) Turn the ignition switch to ON.
4) Run the Subaru Select Monitor.
5) Press the mode change switch to enter the
manual mode.
6) Release the parking brake.
7) Press the C.DIFF +/– switch to enter the
lock position.
8) Read the data of «C-Diff. Indicate Current»
and «C-Diff. Real Current» using Subaru Select
Monitor.

Are «C-Diff. Indicate Current»
and «C-Diff. Real Current» both
approximately 3.6 — 4.0 A?

Go to step

16.

Go to step

17.

16

CHECK CENTER DIFFERENTIAL.
1) Using Subaru Select Monitor, operate the
C.DIFF +/– switch so that «C-Diff. Indicate Cur-
rent» becomes 1.6A.
2) Read the data of «C-Diff. Real Current»
using Subaru Select Monitor.

Is «C-Diff. Real Current» about
the same as «C-Diff. Indicate
Current»?

Go to step

18.

Go to step

17.

17

CHECK POOR CONTACT OF HARNESS
CONNECTORS.

Is there poor contact of the har-
ness connector?

Repair the poor
contact.

Go to step

18.

18

CHECK DTC.
1) Clear the memory. <Ref. to 6MT(diag)-13,
Clear Memory Mode.>
2) Read the DTC using the Select Monitor.
<Ref. to 6MT(diag)-12, Read Diagnostic Trou-
ble Code (DTC).>

Is P1875 displayed?

Check the poor
contact.

Go to step

19.

19

CHECK DTC.

Are DTCs other than P1875
displayed?

Perform the diag-
nosis according to
DTC.

The center differ-
ential circuit is cur-
rently operating
properly.

Step

Check

Yes

No

6MT(diag)-28

Diagnostic Procedure without Diagnostic Trouble Code (DTC)

MANUAL TRANSMISSION AND DIFFERENTIAL (DIAGNOSTICS)

14.Diagnostic Procedure without Diagnostic Trouble Code (DTC)

A: CHECK REAR DIFFERENTIAL OIL TEMPERATURE SWITCH

DIAGNOSIS:

Input signal circuit of rear differential oil temperature switch is open or shorted.

TROUBLE SYMPTOM:

• Center differential remains free

• An oversteer tendency will become apparent.

• Rear differential oil temperature warning light illuminates.

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 REAR DIFFERENTIAL OIL TEMPER-
ATURE SWITCH WARNING LIGHT CIRCUIT.
1) Turn the ignition switch to OFF.
2) Disconnect the DCCD control module har-
ness connector.
3) Turn the ignition switch to ON.
4) Measure the voltage of the rear differential
oil temperature switch.

Connector & terminal

(B380) No. 5 (+) — Chassis ground (–):

Is the voltage less than 0.4 V? Go to step

6.

Go to step

2.

17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

16

15

14

13

12

11

10

40

2

5

B380

8

i10

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

B92

i102

40

39

8

3

7

3

6

3

5

3

34

3

3

2

3

1

3

0

3

9

2

8

2

7

2

6

2

5

2

4

2

3

2

2

2

1

2

20

9

1

8

1

7

1

6

1

5

1

4

1

3

1

2

1

1

1

0

1

9

1 2 3 4 5 6 7 8

i10

16

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

9

8

7

6

5

4

3

2

1

B380

R5

B92

R159

R148

i102

R167

MT-02318

E

FB-36

F/B FUSE NO. 5

(IG)

REAR DIFFERENTIAL

OIL TEMPERATURE SWITCH

COMBINATION

METER

TO POWER SUPPLY CIRCUIT

REVERSE CIRCUIT

REAR

DIFFERENTIAL

OIL TEMPERATURE

WARNING LIGHT

DCCD CM

6MT(diag)-29

Diagnostic Procedure without Diagnostic Trouble Code (DTC)

MANUAL TRANSMISSION AND DIFFERENTIAL (DIAGNOSTICS)

2

CHECK HARNESS BETWEEN DCCD CON-
TROL MODULE AND COMBINATION
METER.
1) Turn the ignition switch to OFF.
2) Disconnect the harness connector from the
combination meter.
3) Disconnect the connector from the rear dif-
ferential oil temperature switch.
4) Measure the resistance between combina-
tion meter and DCCD control module harness
connectors.

Connector & terminal

(B380) No. 5 — (i10) No. 40:

Is the resistance less than 1 Ω? Go to step

3.

Repair the open
circuit between
DCCD control
module and the
combination meter.

3

CHECK HARNESS BETWEEN DCCD CON-
TROL MODULE AND REAR DIFFERENTIAL
OIL TEMPERATURE SWITCH.
Measure the resistance between DCCD control
module harness connector and rear differential
oil temperature switch harness connector.

Connector & terminal

(B380) No. 5 — (R148) No. 1:

Is the resistance less than 1 Ω? Go to step

4.

Repair the open
circuit between
DCCD control
module and rear
differential oil tem-
perature switch.

4

CHECK REAR DIFFERENTIAL OIL TEMPER-
ATURE SWITCH GROUND CIRCUIT.
1) Disconnect the harness connector from the
bracket ground of the rear differential.
2) Measure the resistance between the rear
differential oil temperature switch ground har-
ness connector and chassis ground.

Connector & terminal

(R159) No. 1 — Chassis ground:

Is the resistance 1 MΩ or
more?

Repair the open
circuit of the rear
differential oil tem-
perature switch
ground circuit, and
contact failure of
the harness con-
nector.

Go to step

5.

5

CHECK REAR DIFFERENTIAL OIL TEMPER-
ATURE SWITCH.
Measure the resistance between the rear differ-
ential oil temperature switch and the rear differ-
ential oil temperature switch body.

Connector & terminal

(R148) No. 1 — Rear differential oil tem-
perature switch body:

Is the resistance less than 1 Ω? Go to step

6.

Replace the rear
differential oil tem-
perature switch.

6

CHECK REAR DIFFERENTIAL OIL TEMPER-
ATURE WARNING LIGHT.
1) Turn the ignition switch to ON.
2) Short the chassis ground and the combina-
tion meter harness connector.

Connector & terminal

(i10) No. 40 (+) — Chassis ground (–):

Does the rear differential oil
temperature light turn OFF?

Check the poor
contact.

Check the combi-
nation meter.

Step

Check

Yes

No

6MT(diag)-30

Diagnostic Procedure without Diagnostic Trouble Code (DTC)

MANUAL TRANSMISSION AND DIFFERENTIAL (DIAGNOSTICS)

B: CHECK PARKING BRAKE SWITCH

DIAGNOSIS:

Input signal circuit of parking brake switch is open or shorted.

TROUBLE SYMPTOM:

• It does not show a differential free tendency even when the parking brake switch is applied.

• Remains differential free even when the parking brake switch is released.

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 IGNITION CIRCUIT OF DCCD CON-
TROL MODULE.
1) Connect the Subaru Select Monitor to the
vehicle.
2) Turn the ignition switch to ON.
3) Read the data of «Battery voltage» using
Subaru Select Monitor.

Is the voltage 11 V or more?

Go to step

2.

Repair the open
circuit of harness
between fuse (F/B
No. 12) and DCCD
control module, or
between fuse (F/B
No. 12) and bat-
tery.

2

CHECK DTC.

Is DTC P1720 displayed?

Perform the diag-
nosis according to
DTC.

Go to step

3.

3

CHECK DCCD CONTROL MODULE.
1) Operate the parking brake lever.
2) Read the data of «Parking Position Switch»
using Subaru Select Monitor.

Is the ON/OFF normally
detected?

The parking brake
switch circuit is
currently operating
properly.

Go to step

4.

4

CHECK BODY INTEGRATED UNIT.
1) Operate the parking brake lever.
2) Read the data of «Parking Position Switch»
using Subaru Select Monitor.

Is the ON/OFF normally
detected?

Go to step

7.

Go to step

5.

3

3

1 2 3 4 5

B437

B438

B438

B437

B99

1 2

3 4 5

6 7 8 9 10 11 12

B380

2

1

3 4

6

5

7 8 9 10 11 12 13 14 15 16

17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

B280

B:

6

4 5

3

1 2

9

7 8

7

1

6

1

5

1

4

1

3

1

2

1

1

1

0

1

0

2

9

1

8

1

4

2

3

2

2

2

1

2

6

2

5

2

5

R3

B99

R4

C15

B281

C:

7

5 6

8

2

1

9

4

3

10

24 25

3

2

2

2

11 12 13 14 15

28

7

2

6

2

16 17 18 19

21

0

2

C: B281

B: B280

1

8

B3

B9

2

B380

MT-02931

DCCD CM

BODY INTEGRATED UNIT

PARKING BRAKE

SWITCH