Subaru Legacy IV (2008 year). Manual - part 706

4AT(diag)-45

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

Step

Check

Yes

No

1

CHECK TORQUE CONVERTER TURBINE 
SPEED SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from transmis-
sion.
3) Measure the resistance between transmis-
sion connector receptacle’s terminals.

Connector & terminal

(T4) No. 5 — No. 10:

Is the resistance 450 — 650 

:? Go to step 2.

Replace the torque 
converter turbine 
speed sensor. 
<Ref. to 4AT-53, 
Torque Converter 
Turbine Speed 
Sensor.>

2

CHECK HARNESS CONNECTOR BETWEEN 
TCM AND TRANSMISSION.
1) Disconnect the connector from TCM.
2) Measure the resistance of harness between 
TCM connector and transmission connector.

Connector & terminal

(B54) No. 1 — (B11) No. 5:

Is the resistance less than 1 

:? Go to step 3.

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

3

CHECK HARNESS CONNECTOR BETWEEN 
TCM AND TRANSMISSION.
Measure the resistance of harness between 
TCM connector and transmission connector.

Connector & terminal

(B54) No. 2 — (B11) No. 10:

Is the resistance less than 1 

:? Go to step 4.

Repair the open 
circuit of harness 
between TCM and 
transmission con-
nector, and poor 
contact of the con-
nector.

4

CHECK HARNESS CONNECTOR BETWEEN 
TCM AND TRANSMISSION.
Measure the resistance of harness between 
TCM connector and chassis ground.

Connector & terminal

(B54) No. 2 — Chassis ground:

Is the resistance 1 M

: or 

more?

Go to step 5.

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

5

CHECK HARNESS CONNECTOR BETWEEN 
TCM AND TRANSMISSION.
Measure the resistance of harness between 
TCM connector and chassis ground.

Connector & terminal

(B54) No. 1 — Chassis ground:

Is the resistance 1 M

: or 

more?

Go to step 6.

Repair the short 
circuit of the har-
ness between 
TCM and transmis-
sion connector, 
and poor contact of 
connector.

6

CHECK INPUT SIGNAL FOR TCM USING 
SUBARU SELECT MONITOR.
1) Connect the connectors to TCM and trans-
mission.
2) Connect the Subaru Select Monitor to data 
link connector.
3) Turn the ignition switch to ON and run the 
Subaru Select Monitor.
4) Start the engine.
5) Shift the select lever to “P” or “N” range.
6) Read the data of “Turbine Revolution 
Speed” using Subaru Select Monitor.
• Compare the tachometer with Subaru Select 
Monitor indications.

Is the revolution value same as 
the tachometer reading shown 
on the combination meter?

Even if the ATF 
temperature warn-
ing light blinks, the 
circuit is in normal 
condition at this 
time. A temporary 
poor contact of 
connector or har-
ness may be the 
cause. Repair the 
harness or con-
nector in TCM and 
transmission.

Go to step 7.

7

CHECK POOR CONTACT.

Is there poor contact in torque 
converter turbine speed sensor 
circuit?

Repair the poor 
contact.

Replace the TCM. 
<Ref. to 4AT-61, 
Transmission Con-
trol Module 
(TCM).>

4AT(diag)-46

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

E: DTC P0719 BRAKE SWITCH CIRCUIT LOW

DTC DETECTING CONDITION:
Brake switch malfunction, open input signal circuit
TROUBLE SYMPTOM:
Gear is not shifted down when driving a down hill.
WIRING DIAGRAM:

1

*

2

*

B159

2

1

3 4
8 9

7

6

5

B280

B281

C:

B:

B159

B280

B:

B281

C:

C23

B20

B30

3

5

9

M

AIN SBF

SBF-2

N

o

.8

E

18

17

TCM

B54

B365

2

4

3

B65

1

2

3

4

B65

B365

9

8

7

6

5

4

3

2

1

10

11 12 13 14 15 16 17 18 19

B225

1

*

2

*

1

*

2

*

7.5A

B54

B225

13
14

15 16

17

27

24

25
26

20

21
22

23

29
30

31

28

32

35

33
34

37
38

39

36

40

8

9

10

11 12

1

2

5

3

4

7

6

19

18

CAN JOINT 
CONNECTOR

20

5

4

6 7

8

2

1

9

3

10

22

23

11 12 13 14 15

24 25

26 27

16 17 18

28 29

19 20

21

30

5 6 7

8

2

1

9

4

3

10

24

22 23

25

11 12 13 14 15

26

27 28

16 17 18 19

20 21

16

10 11 12 13 14 15

25

24

30

9

8

7

17 18 19 20
28

21 22 23

29

32

31

1

2

3

4

5

6

27

26

33 34 35

AT-04331

: TERMINAL No. OPTIONAL 
  ARRANGEMENT 
  AMONG 1, 2, 3, 11, 12  AND 13
: TERMINAL No. OPTIONAL 
  ARRANGEMENT 
  AMONG 8, 9, 10, 18, 19  AND 20

BODY INTEGRATED UNIT

FUSE & RELAY 
BOX (F/B)

FUSE
(RELAY BLOCK)

B

A

TTER

Y

STOP LIGHT 
SWITCH

(BLACK)

4AT(diag)-47

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

Step

Check

Yes

No

1

CHECK DTC.

Is DTC of CAN communication 
displayed?

Perform the diag-
nosis according to 
DTC.

Go to step 2.

2

CHECK FUSE (NO. 8).
1) Turn the ignition switch to OFF.
2) Remove the fuse (No. 8).

Is the fuse (No. 8) blown out?

Replace the fuse 
(No. 8). If the 
replaced fuse (No. 
8) has blown out 
easily, repair the 
short circuit of har-
ness between fuse 
(No. 8) and stop 
light switch.

Go to step 3.

3

CHECK FUSE (RELAY BLOCK) (7.5A).
Remove the fuse (relay block) (7.5 A).

Is the fuse (7.5A) blown out?

Replace the fuse 
(7.5A). If the 
replaced fuse 
(7.5A) blows out 
easily, repair the 
short circuit of har-
ness between fuse 
(7.5A) and TCM.

Go to step 4.

4

CHECK BODY INTEGRATED UNIT.
1) Turn the ignition switch to OFF.
2) Connect the Subaru Select Monitor to data 
link connector.
3) Turn the ignition switch to ON. (engine OFF)
4) Run the Subaru Select Monitor.
5) Depress the brake pedal.
6) Read the data of “Stop Light Switch” using 
Subaru Select Monitor. <Ref. to LAN(diag)-12, 
OPERATION, Subaru Select Monitor.>

Is ON displayed?

Go to step 5.

Go to step 6.

5

CHECK TCM.
Read the data of “Stop Light Switch” using Sub-
aru Select Monitor. <Ref. to 4AT(diag)-16, 
OPERATION, Subaru Select Monitor.>

Is ON displayed?

A temporary poor 
contact of connec-
tor or harness may 
be the cause. 
Check the poor 
contact.

Replace the TCM. 
<Ref. to 4AT-61, 
Transmission Con-
trol Module 
(TCM).>

6

CHECK BODY INTEGRATED UNIT INPUT 
SIGNAL.
1) Disconnect the connector from body inte-
grated unit.
2) Depress the brake pedal.
3) Measure the voltage of harness between 
the body integrated unit and chassis ground.

Connector & terminal

(B281) No. 23 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Go to step 9.

Go to step 7.

7

CHECK HARNESS CONNECTOR BETWEEN 
BODY INTEGRATED UNIT AND STOP LIGHT 
SWITCH.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from stop light 
switch.
3) Measure the resistance of harness between 
body integrated unit and stop light switch.

Connector & terminal

(B281) No. 23 — (B65) No. 3:

Is the resistance less than 1 

:? Go to step 8.

Repair the open 
circuit of harness 
between body inte-
grated unit and 
stop light switch.

4AT(diag)-48

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

8

CHECK HARNESS CONNECTOR BETWEEN 
BODY INTEGRATED UNIT AND STOP LIGHT 
SWITCH.
Measure the resistance of harness between 
body integrated unit and stop light switch.

Connector & terminal

(B281) No. 23 — Chassis ground:

Is the resistance 1 M

: or 

more?

Go to step 9.

Repair the short 
circuit of harness 
between body inte-
grated unit and 
stop light switch.

9

CHECK POOR CONTACT.

Is there poor contact in input 
signal of brake switch?

Repair the poor 
contact.

Check the body 
integrated unit.

Step

Check

Yes

No