Subaru Legacy IV (2008 year). Manual — part 710

4AT(diag)-61

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

Step

Check

Yes

No

1

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

Connector & terminal

(B54) No. 3 — (B11) No. 2:
(B54) No. 4 — (B11) No. 1:

Is the resistance less than 1

:? Go to step 2.

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

2

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

Connector & terminal

(B54) No. 3 — Chassis ground:
(B54) No. 4 — Chassis ground:

Is the resistance 1 M

: or

more?

Go to step 3.

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

3

CHECK LINE PRESSURE LINEAR SOLE-
NOID.
Measure the resistance between transmission
connector receptacle’s terminals.

Connector & terminal

(T4) No. 1 — No. 2:

Is the resistance 4 — 8

:?

Go to step 5.

Go to step 4.

4

CHECK LINE PRESSURE LINEAR SOLE-
NOID (IN TRANSMISSION).
1) Remove the transmission connector from
bracket.
2) Drain the automatic transmission fluid.

CAUTION:
Do not drain ATF until it cools down.
3) Remove the oil pan, and disconnect the
connector from control valve body.
4) Measure the resistance of line pressure lin-
ear solenoid connector terminals.

Connector & terminal

(AT2) No. 5 — No. 10:

Is the resistance 4 — 8

:?

Go to step 5.

Replace the con-
trol valve body.
<Ref. to 4AT-56,
Control Valve
Body.>

5

CHECK HARNESS CONNECTOR BETWEEN
TRANSMISSION AND LINE PRESSURE LIN-
EAR SOLENOID.
Measure the resistance of harness between
line pressure linear solenoid and transmission
connector.

Connector & terminal

(T4) No. 2 — (AT2) No. 10:
(T4) No. 1 — (AT2) No. 5:

Is the resistance less than 1

:? Go to step 6.

Repair the open
circuit of harness
between line pres-
sure linear sole-
noid and
transmission con-
nector.

6

CHECK HARNESS CONNECTOR BETWEEN
TRANSMISSION AND LINE PRESSURE LIN-
EAR SOLENOID.
Measure the resistance of harness between
transmission connector and transmission
ground.

Connector & terminal

(T4) No. 1 — Transmission ground:
(T4) No. 2 — Transmission ground:

Is the resistance 1 M

: or

more?

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 line pres-
sure linear
solenoid and trans-
mission.

Repair the short
circuit of harness
between line pres-
sure linear sole-
noid and
transmission con-
nector.

4AT(diag)-62

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

Q: DTC P0753 SHIFT SOLENOID “A” ELECTRICAL

DTC DETECTING CONDITION:
Output signal circuit of low clutch duty solenoid is open or shorted.
TROUBLE SYMPTOM:
Excessive shift shock
WIRING DIAGRAM:

AT-04770

TCM

B11

1

2

3 4

5

6 7

8

9

13

14 15

20

19

17

16

10

11 12

18

7

B55

B11

AT 2

T4

4

2

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

AT2

10

9

8

7

6

5

4

3

2

1

CONTROL VALVE BODY

LOW
CLUTCH
DUTY
SOLENOID

4AT(diag)-63

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

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

(B55) No. 7 — (B11) No. 4:

Is the resistance less than 1

:? 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 connector and transmission ground.

Connector & terminal

(B55) No. 7 — Chassis ground:

Is the resistance 1 M

: or

more?

Go to step 3.

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

3

CHECK LOW CLUTCH DUTY SOLENOID.
Measure the resistance between transmission
connector terminals.

Connector & terminal

(T4) No. 4 — No. 20:

Is the resistance 2.0 — 6.0

:? Go to step 4.

Go to step 7.

4

CHECK OUTPUT SIGNAL FROM TCM US-
ING SUBARU SELECT MONITOR.
1) Connect the connectors to TCM and trans-
mission.
2) Connect the Subaru Select Monitor to data
link connector.
3) Start the engine, and run the Subaru Select
Monitor.
4) Warm up the transmission until the ATF
temperature exceeds approximately 80°C
(176°F).

NOTE:
If the ambient temperature falls below 0°C
(32°F), drive the vehicle until the ATF reaches
its operating temperature.
5) Stop the engine and turn the ignition switch
to ON (with engine OFF).
6) Shift the select lever to “P” or “N” range, and
depress the accelerator pedal.
7) Read the data of “Low Clutch Duty” using
Subaru Select Monitor.
• Low clutch duty solenoid is indicated in “%”.

Is the measured value 100%?

Go to step 5.

Go to step 6.

5

CHECK OUTPUT SIGNAL FROM TCM US-
ING SUBARU SELECT MONITOR.
1) Turn the ignition switch to ON (engine OFF).
2) Shift the select lever to “D” range.
3) Read the data of “Low Clutch Duty”.

Is the measured value 0%?

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 transmis-
sion.

Go to step 6.

6

CHECK POOR CONTACT.

Is there poor contact in low
clutch duty solenoid circuit?

Repair the poor
contact.

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

4AT(diag)-64

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

7

CHECK LOW CLUTCH DUTY SOLENOID (IN
TRANSMISSION).
1) Remove the transmission connector from
bracket.
2) Drain the automatic transmission fluid.

CAUTION:
Do not drain ATF until it cools down.
3) Remove the oil pan, and disconnect the
connector from control valve body.
4) Measure the resistance between low clutch
duty solenoid connector and transmission
ground.

Connector & terminal

(AT2) No. 2 — Transmission ground:

Is the resistance 2.0 — 6.0

:? Go to step 8.

Replace the con-
trol valve body.
<Ref. to 4AT-56,
Control Valve
Body.>

8

CHECK HARNESS CONNECTOR BETWEEN
TRANSMISSION AND LOW CLUTCH DUTY
SOLENOID.
Measure the resistance of harness between low
clutch duty solenoid and transmission connec-
tor.

Connector & terminal

(T4) No. 4 — (AT2) No. 2:

Is the resistance less than 1

:? Go to step 9.

Repair the open
circuit of harness
between low clutch
duty solenoid and
transmission con-
nector.

9

CHECK HARNESS CONNECTOR BETWEEN
TRANSMISSION AND LOW CLUTCH DUTY
SOLENOID.
Measure the resistance of harness between
transmission connector and transmission
ground.

Connector & terminal

(T4) No. 4 — Transmission ground:

Is the resistance 1 M

: or

more?

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 of the low
clutch duty sole-
noid and transmis-
sion.

Repair the short
circuit of harness
between low clutch
duty solenoid and
transmission con-
nector.

Step

Check

Yes

No