Subaru Legacy (2005 year). Manual - part 554

4AT(diag)-53

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

F: DTC P0720 OUTPUT SPEED SENSOR CIRCUIT

DTC DETECTING CONDITION:
• The vehicle speed signal is abnormal.
• The harness connector between TCM and vehicle speed sensor is in short or open.
TROUBLE SYMPTOM:
• The neutralizing control does not operate.
• The slip lock up control does not operate.
• Poor driving performance.
WIRING DIAGRAM:

AT-03160

LH RH

LH

RH

18

14

B11

T4

6

B11

1

2

3 4

5

6 7

8

9

13

14 15

20

19

17

16

10

11 12

18

TCM

B54

       FRONT
VEHICLE SPEED
      SENSOR

B54

1 2

7

8 9

5

6

3

4

10 11 12
19 20 21

13 14 15 16

17 18

22 23 24

B53

15

B53

JOINT
CONNECTOR

1 2 3 4 5 6 7 8 9 10

11 12 13 14 15 16 17 18 19 20

: LHD MODEL

LH

RH : RHD MODEL

*

: TERMINAL No. RANDOM ARRANGEMENT
  AMONG 1,11, AND 12

* *

*

*

*

*

4AT(diag)-54

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

Step

Check

Yes

No

1

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

Connector & terminal

(B54) No. 6 — (B11) No. 14:

Is the resistance less than 1 
Ω?

Go to step 2.

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

2

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

Connector & terminal

(B54) No. 15 — (B11) No. 18:

Is the resistance less than 1 
Ω?

Go to step 3.

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

3

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

Connector & terminal

(B54) No. 6 — Chassis ground:

Is the resistance more than 1 
M

Ω?

Go to step 4.

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

4

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

Connector & terminal

(B54) No. 15 — Chassis ground:

Is the resistance more than 1 
M

Ω?

Go to step 5.

Repair the short 
circuit of harness 
between TCM and 
transmission con-
nector, and poor 
contact in connec-
tor.

5

CHECK FRONT VEHICLE SPEED SENSOR.
Measure the resistance between transmission 
connector receptacle’s terminals.

Connector & terminal

(T4) No. 14 — No. 18:

Is the resistance 450 — 650 
Ω?

Go to step 6.

Replace the front 
vehicle speed sen-
sor. <Ref. to 4AT-
55, Front Vehicle 
Speed Sensor.>

4AT(diag)-55

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

6

CHECK INPUT SIGNAL FOR TCM USING 
SUBARU SELECT MONITOR.
1) Connect all the connectors.
2) Connect the Subaru Select Monitor to data 
link connector.
3) Lift-up the vehicle.

NOTE:

Raise all wheels off floor.

4) Turn the ignition switch to ON and the Sub-
aru Select Monitor power switch to ON.
5) Start the engine.
6) Read the data of vehicle speed using Sub-
aru Select Monitor.
• Compare the speedometer with Subaru 
Select Monitor indications.
• Vehicle speed is indicated in “km/h” or 
“MPH”.
7) Slowly increase the vehicle speed to 60 km/
h (37 MPH).

NOTE:

The speed difference between front and rear
wheels may light the ABS warning light or VDC
warning light, but this indicates no malfunction.
When AT control diagnosis is finished, perform
the ABS memory clearance procedure or VDC
memory clearance procedure of on-board diag-
nostics system. <Ref. to ABS(diag)-26, Clear
Memory Mode.> <Ref. to VDC(diag)-25, Clear
Memory Mode.>

Does the speedometer indica-
tion increase as the front wheel 
vehicle speed data of Subaru 
Select Monitor increases?

Even if the SPORT 
indicator light is 
blinking, the cir-
cuit has returned 
to normal condi-
tion at this time. A 
temporary poor 
contact of connec-
tor or harness may 
be the cause. 
Repair the har-
ness in the front 
vehicle speed sen-
sor circuit.

Go to step 7.

7

CHECK POOR CONTACT.

Is there poor contact in front 
vehicle speed sensor circuit?

Repair the poor 
contact.

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

Step

Check

Yes

No

4AT(diag)-56

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

G: DTC P0724 TORQUE CONVERTER/BRAKE SWITCH “B” CIRCUIT HIGH

DTC DETECTING CONDITION:
Brake switch malfunction, open input signal circuit
TROUBLE SYMPTOM:
• Gear is not shifted down when driving a down hill.
• The neutralizing control does not operate.
WIRING DIAGRAM:
• LHD model

AT-03158

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

B64

2

1

B54

8

3

4

5

6

7

2

1

18 19 20

17

16

15

14

13

12

11

10

9

24

23

22

21

C:

B:

B159

B280

B:

B281

C:

C23

B20

B30

3

5

9

MAIN SBF

SBF-2

No.8

E

B

A

TTER

Y

STOP LIGHT
SWITCH

JOINT
CONNECTOR

BODY INTEGRATED
MODULE

3

12

TCM

B54

2

4

5

7

B352

JOINT
CONNECTOR

B355

JOINT
CONNECTOR

2

WC

WC

1

OC

2

OC

: WITHOUT CRUISE CONTROL

: WITH CRUISE CONTROL

OC

WC

OC

WC

: 

: 

B64

B65

1

2

3

4

B65

1 2 3 4
5 6 7 8

B54

B355

B352

OC

WC

: 

: 

1

*

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

2

*

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

2

*

2

*

1

*

1

*