Subaru Legacy IV (2008 year). Manual — part 760

5AT(diag)-55

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

N: DTC P0741 TORQUE CONVERTER CLUTCH CIRCUIT PERFORMANCE OR

STUCK OFF

DTC DETECTING CONDITION:
• Defective lock-up clutch or torque converter assembly
• Defective control valve
• Defective turbine speed sensor 1 or 2
TROUBLE SYMPTOM:
No lock-up occurs. (After engine is warmed up)

5AT(diag)-56

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

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, P1710, P1718

Perform the diag-
nosis according to
each DTC.

Go to step 2.

2

DRIVING CHECK FOR LOCK-UP CONDI-
TION.
1) Perform a drive check based on the Inspec-
tion Mode with the following conditions. <Ref. to
5AT(diag)-22, PROCEDURE, Inspection
Mode.>

(1) Read the current data of throttle opening
angle using Subaru Select Monitor. <Ref. to
5AT(diag)-18, READ CURRENT DATA,
OPERATION, Subaru Select Monitor.>
(2) Keep the same vehicle speed at 60 km/h
with 10% or less throttle opening angle
which is read currently on Subaru Select
Monitor. <Ref. to 5AT(diag)-18, READ CUR-
RENT DATA, OPERATION, Subaru Select
Monitor.>
(3) Read the data of L/U Solenoid Pressure
using Subaru Select Monitor. <Ref. to
5AT(diag)-18, READ CURRENT DATA,
OPERATION, Subaru Select Monitor.>
(4) Check the engine speed and turbine
speed when the L/U solenoid target value
displayed on Subaru Select Monitor is 500
kPa or more.

Are the engine speed and tur-
bine speed almost the same?

Temporary poor
contact or open cir-
cuit occurs.
Recheck that the
harness connector
has no faulty.

Go to step 3.

3

DRIVING CHECK FOR LOCK-UP CONDI-
TION.
1) Clear the memory. <Ref. to 5AT(diag)-20,
CLEAR MEMORY MODE, OPERATION, Sub-
aru Select Monitor.>
2) Perform a drive check based on the Inspec-
tion Mode with the following conditions. <Ref. to
5AT(diag)-22, PROCEDURE, Inspection
Mode.>

(1) Read the current data of throttle opening
angle using Subaru Select Monitor. <Ref. to
5AT(diag)-18, READ CURRENT DATA,
OPERATION, Subaru Select Monitor.>
(2) Keep the same vehicle speed at 60 km/h
with 10% or less throttle opening angle
which is read currently on Subaru Select
Monitor. <Ref. to 5AT(diag)-18, READ CUR-
RENT DATA, OPERATION, Subaru Select
Monitor.>
(3) Read the data of L/U Solenoid Pressure
using Subaru Select Monitor. <Ref. to
5AT(diag)-18, READ CURRENT DATA,
OPERATION, Subaru Select Monitor.>
(4) Drive the vehicle continuously for one
minute or more with the L/U solenoid target
value displayed on Subaru Select Monitor at
500 kPa or more.

3) Turn the ignition switch to OFF.
4) Turn the ignition switch to ON. (Engine ON)
5) Perform the step 2) again.

Does the AT OIL TEMP light
blink and is DTC P0741 dis-
played?

Replace the trans-
mission assembly
when DTC P0741
is displayed.
When DTC other
than P0741 is dis-
played, perform
the diagnosis cor-
responding to the
DTC.

Temporary poor
contact or open cir-
cuit occurs.
Recheck that the
harness connector
has no faulty.

5AT(diag)-57

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

O: DTC P0743 TORQUE CONVERTER CLUTCH CIRCUIT ELECTRICAL

DTC DETECTING CONDITION:
Output signal circuit of lock-up pressure linear solenoid is open or shorted.
TROUBLE SYMPTOM:
No lock-up occurs. (After engine is warmed up)
WIRING DIAGRAM:

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 connector and transmission connector.

Connector & terminal

(B55) No. 22 — Chassis ground:
(B55) No. 23 — Chassis ground:
(B54) No. 7 — (B11) No. 20:

Is the resistance less than 1

:? Go to step 2.

Repair the open
circuit of harness
between TCM con-
nector and trans-
mission connector.

2

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

Connector & terminal

(B54) No. 7 — Chassis ground:

Is the resistance 1 M

: or

more?

Go to step 3.

Repair the short
circuit of harness
between TCM con-
nector and trans-
mission connector.

AT-04352

B11

1

2

3 4

5

6 7

8

9

13

14 15

20

19

17

16

10

11 12

18

A7

B11

T11

20

5

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

33 34

29

32

30

31

35

CONTROL VALVE BODY

1 2 3 4
5 6 7 8

T11

T4

LOCK-UP PRESSURE
LINEAR SOLENOID

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

TCM

B54

A:

B55

B:

B22

B23

E

B54

A:

B55

B:

5AT(diag)-58

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

3

CHECK HARNESS CONNECTOR BETWEEN
TRANSMISSION AND CONTROL VALVE
BODY.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from transmis-
sion.
3) Remove the transmission connector from
bracket.
4) Lift up the vehicle.

NOTE:
Raise all wheels off the floor.
5) Drain the ATF.

NOTE:
Do not drain ATF until it cools down.
6) Remove the oil pan, and disconnect the
control valve body connector.
7) Measure the resistance between transmis-
sion connector and control valve body connec-
tor.

Connector & terminal

(T4) No. 20 — (T11) No. 5:

Is the resistance less than 1

:? Go to step 4.

Repair the open
circuit of harness
between transmis-
sion connector and
control valve body
connector.

4

CHECK HARNESS CONNECTOR BETWEEN
TRANSMISSION AND CONTROL VALVE
BODY.
Measure the resistance between transmission
ground and control valve body connector.

Connector & terminal

(T11) No. 5 — Transmission ground:

Is the resistance 1 M

: or

more?

Repair the open
circuit of harness
between control
valve body con-
nector and trans-
mission ground.

Go to step 5.

5

CHECK LOCK-UP PRESSURE LINEAR SO-
LENOID.
Measure the resistance between transmission
ground and control valve body connector.

Connector & terminal

(T11) No. 5 — Transmission ground:

Is the resistance 3 — 9

:?

Go to step 6.

Replace the con-
trol valve body.
<Ref. to 5AT-57,
Control Valve
Body.>

6

CHECK POOR CONTACT.
Check that there are no poor contact in TCM
connector, transmission connector and control
valve body connector.

Is there any loosing terminal,
entering foreign matter, damag-
ing connector body?

Repair the poor
contact.

Go to step 7.

7

CHECK AFTER REPAIR.
1) Perform the Clear Memory Mode.
2) Drive for a while, read the DTC, and check
that there is no faulty.

Is DTC displayed?

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

Temporary poor
contact or open cir-
cuit occurs.
Recheck that the
harness connector
has no faulty.

Step

Check

Yes

No