Subaru Legacy (2005 year). Manual - part 571

4AT(diag)-121

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

Diagnostic Procedure without Diagnostic Trouble Code (DTC)

Step

Check

Yes

No

1

CONFIRM EQUIPMENT OF VEHICLE.

Is the vehicle equipped with 
VDC?

Go to “CHECK 
MANUAL MODE 
SWITCH”. <Ref. to 
4AT(diag)-123, 
CHECK MANUAL 
MODE SWITCH, 
Diagnostic Proce-
dure without Diag-
nostic Trouble 
Code (DTC).>

Go to step 2.

2

CHECK SPARE FUSE.

Is the spare fuse OK?

Go to step 3.

Replace the fuse.

3

CHECK FWD SWITCH.
Connect the Subaru Select Monitor to data link 
connector.

When the fuse is inserted to 
FWD switch, does the LED 
light up?

Go to step 4.

Go to step 5.

4

CHECK COMBINATION METER.

Does the AWD warning light 
illuminate?

Go to “CHECK 
MANUAL MODE 
SWITCH”. <Ref. to 
4AT(diag)-123, 
CHECK MANUAL 
MODE SWITCH, 
Diagnostic Proce-
dure without Diag-
nostic Trouble 
Code (DTC).>

Go to step 10.

5

CHECK HARNESS CONNECTOR BETWEEN 
TCM AND FWD SWITCH.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from TCM.
3) Measure the resistance of harness 
between TCM and FWD switch connector.

Connector & terminal

(B55) No. 17 — (F27) No. 18:

Is the resistance less than 1 
Ω?

Go to step 6.

Repair the open 
circuit of harness 
between TCM and 
FWD switch con-
nector.

6

CHECK HARNESS CONNECTOR BETWEEN 
FWD SWITCH AND CHASSIS GROUND.
Measure the resistance of harness between 
FWD switch and chassis ground.

Connector & terminal

(F27) No. 19 — Chassis ground:

Is the resistance less than 1 
Ω?

Go to step 7.

Repair the open 
circuit of harness 
between FWD 
switch connector 
and chassis 
ground.

7

CHECK HARNESS CONNECTOR BETWEEN 
TCM AND FWD SWITCH.
Measure the resistance of harness connector 
between TCM and body to make sure that cir-
cuit does not short.

Connector & terminal

(B55) No. 17 — Chassis ground:

Is the resistance more than 1 
M

Ω?

Go to step 8.

Repair the short 
circuit of harness 
between TCM and 
FWD switch con-
nector.

8

CHECK INPUT SIGNAL FOR TCM.
1) Turn the ignition switch to OFF.
2) Connect the connector to TCM.
3) Turn the ignition switch to ON.
4) Measure the signal voltage for TCM while 
installing the fuse to FWD switch connector.

Connector & terminal

(B55) No. 17 (+) — Chassis ground (

−

):

Is the voltage less than 1 V?

Go to step 9.

Go to step 11.

9

CHECK INPUT SIGNAL FOR TCM.
Measure the signal voltage for TCM while 
removing the fuse from FWD switch connector.

Connector & terminal

(B55) No. 17 (+) — Chassis ground (

−

):

Is the voltage more than 10.5 
V?

Go to step 10.

Replace the TCM. 
<Ref. to 4AT-66, 
Transmission Con-
trol Module 
(TCM).>

4AT(diag)-122

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

Diagnostic Procedure without Diagnostic Trouble Code (DTC)

10

CHECK BODY INTEGRATED MODULE.
Check DTC of body integrated module.

Is DTC of CAN communication 
displayed?

Perform the diag-
nosis according to 
DTC.

Go to step 11.

11

CHECK COMBINATION METER.
Check AWD warning light. <Ref. to IDI-3, 
INSPECTION, Combination Meter System.>

Is the AWD warning light OK?

Go to step 12.

Replace the com-
bination meter 
assembly. <Ref. to 
IDI-15, Combina-
tion Meter.>

12

CHECK POOR CONTACT.

Is there poor contact in FWD 
switch circuit?

Repair the poor 
contact.

Replace the TCM. 
<Ref. to 4AT-66, 
Transmission Con-
trol Module 
(TCM).>

Step

Check

Yes

No

4AT(diag)-123

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

Diagnostic Procedure without Diagnostic Trouble Code (DTC)

B: CHECK MANUAL MODE SWITCH

DIAGNOSIS:
Input signal circuit of manual mode switch is open or shorted.
TROUBLE SYMPTOM:
Does not shift on manual mode.
WIRING DIAGRAM:
• LHD model

AT-03166

B281

C:

B280

B:

B20

B30

C25

C15

3

12

B116

TCM

B54

B280

B54

B281

8

7

6

5

4

3

2

1

22

23

21

20

19

16

15

14

13

12

11

10

9

17

30

18

29

28

27

26

25

24

8

7

6

5

4

3

2

1

22 23

21

20

19

16

15

14

13

12

11

10

9

17 18

28

27

26

25

24

8

3

4

5

6

7

2

1

18 19 20

17

16

15

14

13

12

11

10

9

24

23

22

21

B116

10

9

8

7

6

5

4

3

2

1

E

BODY INTEGRATED MODULE

SELECT
LEVER

B:

C:

2

4

5

7

B352

JOINT
CONNECTOR

B355

JOINT
CONNECTOR

B352

B355

1 2 3 4
5 6 7 8

2

*

2

*

1

*

1

*

1

*

: TERMINAL No. RANDOM ARRANGEMENT
  AMONG 1,2,5, AND 6

2

*

: TERMINAL No. RANDOM ARRANGEMENT
  AMONG 3,4,7, AND 8

5

9

6

10

MANUAL
MODE
SWITCH

UP

DOWN

4AT(diag)-124

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

Diagnostic Procedure without Diagnostic Trouble Code (DTC)

• RHD model

AT-03167

B281

C:

B280

B:

B20

B30

C25

3

12

8

B352

B116

2

4

B53

TCM

B54

C15

E

BODY INTEGRATED MODULE

JOINT
CONNECTOR

JOINT
CONNECTOR

SELECT
LEVER

B280

B352

B53

B54

B281

10

9

8

7

6

5

4

3

2

1

20

19

18

17

16

15

14

13

12

11

8

7

6

5

4

3

2

1

22

23

21

20

19

16

15

14

13

12

11

10

9

17

30

18

29

28

27

26

25

24

8

7

6

5

4

3

2

1

22 23

21

20

19

16

15

14

13

12

11

10

9

17 18

28

27

26

25

24

8

3

4

5

6

7

2

1

18 19 20

17

16

15

14

13

12

11

10

9

24

23

22

21

B116

10

9

8

7

6

5

4

3

2

1

B:

C:

2

1

3 4

8

7

6

5

2

*

2

*

1

*

1

*

6

1

*

: TERMINAL No. RANDOM ARRANGEMENT
  AMONG 8,18, AND 19

2

*

 : TERMINAL No. RANDOM ARRANGEMENT
   AMONG 9,10, AND 20

5

9

6

10

MANUAL
MODE
SWITCH

UP

DOWN