Subaru Legacy IV (2008 year). Service manual — part 759

5AT(diag)-51

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

G: DTC P0724 BRAKE SWITCH CIRCUIT HIGH

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

B280

B:

B281

C:

C23

B20

B30

B159

2

1

3 4
8 9

7

6

5

B280

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

B281

8

7

6

5

4

3

2

1

21

22

20

19

16

15

14

13

12

11

10

9

17 18

28

27

26

25

24

23

21

20

B55

C:

B:

B65

1

2

3

4

TCM

9

5

B65

B225

7.5A

4

3

AT-04350

B55

5

6

7

2

1

3

4

29

10 11 12 13 14 15

25

24

16

30

9

8

17 18 19

20
28

21 22 23

32

31

26 27

33

34 35

1 2 3 4 5 6 7 8 9 10

11 12 13 14 15 16 17 18 19 20

B365

B365

1

*

2

*

1

*

2

*

SBF-2

E

FUSE
(RELAY BLOCK)

3

2

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

RELAY BLOCK

BODY INTEGRATED UNIT

FUSE & RELAY
BOX (F/B)

B159

STOP LIGHT
SWITCH

B

A

TTER

Y

MAIN SBF

No.8

:

:

1

*

2

*

TERMINAL No. OPTIONAL
ARRANGEMENT
AMONG 1, 2 ,3,11,12 AND 13

TERMINAL No. OPTIONAL
ARRANGEMENT
AMONG 8, 9, 10, 18, 19 AND 20

CAN
JOINT
CONNECTOR

5AT(diag)-52

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

Step

Check

Yes

No

1

CHECK DTC.

Is any of following DTC
detected? / AT CAN Communi-
cation Circuit / Output Speed
Sensor Circuit / AT Vehicle
Speed Sensor Circuit Malfunc-
tion (Rear Wheel)

Perform the diag-
nosis according to
DTC.

Go to step 2.

2

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) Turn the Subaru Select Monitor switch to
ON.
5) Read the data of "Stop Light Switch" using
Subaru Select Monitor. <Ref. to LAN(diag)-12,
OPERATION, Subaru Select Monitor.>

Is OFF displayed?

Go to step 3.

Go to step 4.

3

CHECK TCM.
Read the data of "Stop Light Switch" using Sub-
aru Select Monitor. <Ref. to 5AT(diag)-18,
OPERATION, Subaru Select Monitor.>

Is OFF displayed?

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

Replace the TCM.
<Ref. to 5AT-60,
Transmission Con-
trol Module
(TCM).>

4

CHECK BODY INTEGRATED UNIT INPUT
SIGNAL.
1) Disconnect the connector from body inte-
grated unit.
2) Measure the voltage between body inte-
grated unit connector and chassis ground.

Connector & terminal

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

Is the voltage 10 V or more?

Go to step 5.

Go to step 7.

5

CHECK 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
stop light switch connectors.

Connector & terminal

(B65) No. 3 — (B65) No. 2:

Is the resistance 1 M

: or

more?

Go to step 6.

Replace the stop
light switch.

6

CHECK HARNESS CONNECTOR BETWEEN
BODY INTEGRATED UNIT AND STOP LIGHT
SWITCH.
1) Turn the ignition switch to ON.
2) Measure the voltage of harness between
body integrated unit connector and chassis
ground.

Connector & terminal

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

Is the voltage less than 1 V?

Go to step 7.

Repair the short
circuit of harness
between TCM and
stop light switch.

7

CHECK POOR CONTACT.

Is there poor contact in input
signal of brake switch?

Repair the poor
contact.

Check the body
integrated unit.

5AT(diag)-53

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

H: DTC P0731 GEAR 1 INCORRECT RATIO

NOTE:
Refer to DTC P0736 for diagnostic procedure. <Ref. to 5AT(diag)-54, DTC P0736 REVERSE INCORRECT
RATIO, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>

I:

DTC P0732 GEAR 2 INCORRECT RATIO

NOTE:
Refer to DTC P0736 for diagnostic procedure. <Ref. to 5AT(diag)-54, DTC P0736 REVERSE INCORRECT
RATIO, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>

J: DTC P0733 GEAR 3 INCORRECT RATIO

NOTE:
Refer to DTC P0736 for diagnostic procedure. <Ref. to 5AT(diag)-54, DTC P0736 REVERSE INCORRECT
RATIO, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>

K: DTC P0734 GEAR 4 INCORRECT RATIO

NOTE:
Refer to DTC P0736 for diagnostic procedure. <Ref. to 5AT(diag)-54, DTC P0736 REVERSE INCORRECT
RATIO, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>

L: DTC P0735 GEAR 5 INCORRECT RATIO

NOTE:
Refer to DTC P0736 for diagnostic procedure. <Ref. to 5AT(diag)-54, DTC P0736 REVERSE INCORRECT
RATIO, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>

5AT(diag)-54

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

M: DTC P0736 REVERSE INCORRECT RATIO

DTC DETECTING CONDITION:
Target gear ratio and actual gear ratio do not match.
TROUBLE SYMPTOM:
• Shift point is too high or too low.
• Excessive shift shock
• Gear is not changed.
• The vehicle does not move in D or R range with the engine running at high speed.

Step

Check

Yes

No

1

CHECK DTC OF TCM.

Is any DTC of the followings
detected? P0715, P0720,
P0753, P0758, P0763, P0768,
P0773, P0751, P0756, P0761,
P0766, P0771, P1706, P1710,
P1718

Perform the diag-
nosis according to
DTC.

Go to step 2.

2

CHECK TURBINE SPEED SENSOR USING
SUBARU SELECT MONITOR.
1) Lift up the vehicle.

NOTE:
Raise all wheels off the floor.
2) Start the engine, and drive it.
3) Read the current data of torque converter
turbine speed using Subaru Select Monitor.
<Ref. to 5AT(diag)-18, READ CURRENT DATA,
OPERATION, Subaru Select Monitor.>

NOTE:
The speed difference between front and rear
wheels may illuminate the ABS warning light,
but this does not indicate a malfunction. When
AT control diagnosis is finished, perform the
ABS or VDC clear memory of on-board diag-
nostics system. <Ref. to ABS(diag)-20, Clear
Memory Mode.> <Ref. to VDC(diag)-23, Clear
Memory Mode.>

Does the displayed value of the
Subaru Select Monitor change
according to engine speed and
shifting?

Go to step 3.

Perform the diag-
nosis according to
DTC P0715,
P1710.

3

CHECK FRONT AND REAR VEHICLE
SPEED SENSORS.

Do the values displayed for
each of the Subaru Select Mon-
itor and the speedometer sub-
stantially match?

Go to step 4.

Perform the diag-
nosis according to
DTC P0720,
P1706.

4

CHECK INHIBITOR SWITCH.

Do the values displayed for the
Subaru Select Monitor and the
meter indicator match?

Go to step 5.

Perform the diag-
nosis according to
DTC P0705.

5

DRIVING CHECK.
1) Turn the ignition switch to OFF.
2) After restarting the engine, check that the
AT OIL TEMP light is not blinking, and perform a
drive check based on the Inspection Mode.
<Ref. to 5AT(diag)-22, PROCEDURE, Inspec-
tion Mode.>

Is DTC displayed again?

Check the DTC.
Then, when pro-
ceeded again to
step 5, go to step 6.

Go to step 6.

6

CHECK AFTER REPAIR.

Is the trouble symptom unre-
pairable (malfunction in shifting
such as excessive shift shock,
engine speed increases exces-
sively when shifting)?

Replace the trans-
mission assembly.

Temporary poor
contact occurs.
Check that the har-
ness connector is
not faulty.