Subaru Legacy IV (2008 year). Manual — part 704

4AT(diag)-37

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

29

CHECK INPUT SIGNAL FOR TCM.
1) Shift the select lever to any range other than
“N” range.
2) Measure the voltage between TCM and
chassis ground.

Connector & terminal

(B54) No. 11 (+) — Chassis ground (–):

Is the voltage 8 V or more?

Go to step 41.

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

30

CHECK BODY INTEGRATED UNIT.
Read the data of Shift Position from Subaru
Select Monitor. <Ref. to LAN(diag)-12, OPERA-
TION, Subaru Select Monitor.>

Is “5” displayed?

Go to step 31.

Check the body
integrated unit.

31

CHECK BODY INTEGRATED UNIT.
Check DTC of body integrated unit.

Is DTC of CAN communication
displayed?

Perform the diag-
nosis according to
DTC.

Go to step 32.

32

CHECK COMBINATION METER.
Check the “N” range indicator light. <Ref. to IDI-
5, INSPECTION, Combination Meter System.>

Is the “N” range indicator light
OK?

Go to step 41.

Replace the com-
bination meter
assembly. <Ref. to
IDI-22, Combina-
tion Meter.>

33

CHECK HARNESS CONNECTOR BETWEEN
TCM AND INHIBITOR SWITCH.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from TCM, inhib-
itor switch and combination meter.
3) Measure the resistance of harness between
TCM connector and chassis ground.

Connector & terminal

(B54) No. 11 — Chassis ground:

Is the resistance 1 M

: or

more?

Go to step 41.

Repair the ground
short circuit in “N”
range circuit.

34

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

Connector & terminal

(B54) No. 10 — (T7) No. 4:

Is the resistance less than 1

:? Go to step 35.

Repair the open
circuit of harness
between TCM and
inhibitor switch
connector, and
poor contact of the
connector.

35

CHECK INPUT SIGNAL FOR TCM.
1) Turn the ignition switch to OFF.
2) Connect the connector to TCM and inhibitor
switch.
3) Turn the ignition switch to ON.
4) Shift the select lever to “D” range.
5) Measure the voltage between TCM and
chassis ground.

Connector & terminal

(B54) No. 10 (+) — Chassis ground (–):

Is the voltage less than 1 V?

Go to step 36.

Go to step 41.

36

CHECK INPUT SIGNAL FOR TCM.
1) Shift the select lever to any range other than
“D” range.
2) Measure the voltage between TCM and
chassis ground.

Connector & terminal

(B54) No. 10 (+) — Chassis ground (–):

Is the voltage 8 V or more?

Go to step 41.

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

37

CHECK BODY INTEGRATED UNIT.
Read the data of “Inhibitor Switch” from Subaru
Select Monitor. <Ref. to LAN(diag)-12, OPERA-
TION, Subaru Select Monitor.>

Is “4” displayed?

Go to step 38.

Check the body
integrated unit.

Step

Check

Yes

No

4AT(diag)-38

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

38

CHECK BODY INTEGRATED UNIT.
Check DTC of body integrated unit.

Is DTC of CAN communication
displayed?

Perform the diag-
nosis according to
DTC.

Go to step 39.

39

CHECK COMBINATION METER.
Check the “D” range indicator light. <Ref. to IDI-
5, INSPECTION, Combination Meter System.>

Is the “D” range indicator light
OK?

Go to step 41.

Replace the com-
bination meter
assembly. <Ref. to
IDI-22, Combina-
tion Meter.>

40

CHECK HARNESS CONNECTOR BETWEEN
TCM AND INHIBITOR SWITCH.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from TCM, inhib-
itor switch and combination meter.
3) Measure the resistance of harness between
TCM connector and chassis ground.

Connector & terminal

(B54) No. 10 — Chassis ground:

Is the resistance 1 M

: or

more?

Go to step 41.

Repair ground
short circuit in “D”
range circuit.

41

CHECK POOR CONTACT.

Is there poor contact in the
inhibitor switch circuit?

Repair the poor
contact.

Go to step 42.

42

CHECK INHIBITOR SWITCH.

Is the inhibitor switch in the nor-
mal position?

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

Adjust inhibitor
switch and select
cable. <Ref. to
4AT-46, Inhibitor
Switch.> <Ref. to
CS-28, Select
Cable.>

Step

Check

Yes

No

4AT(diag)-39

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

B: DTC P0712 TRANSMISSION FLUID TEMPERATURE SENSOR CIRCUIT LOW

INPUT

DTC DETECTING CONDITION:
Input signal circuit to ATF temperature sensor is open or shorted.
TROUBLE SYMPTOM:
Excessive shift shock
WIRING DIAGRAM:

AT-04767

B11

1

2

3 4

5

6 7

8

9

13

14 15

20

19

17

16

10

11 12

18

23

12

15

11

9

4

B54

B11

AT2

T4

TCM

B54

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

AT2

10

9

8

7

6

5

4

3

2

1

CONTROL VALVE BODY

ATF
TEMPERATURE
SENSOR

4AT(diag)-40

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

Step

Check

Yes

No

1

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

Connector & terminal

(B54) No. 23 — (B11) No. 11:

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 ATF TEMPERATURE SENSOR.
Measure the resistance of harness between
TCM and transmission connector.

Connector & terminal

(B54) No. 12 — (B11) No. 15:

Is the resistance less than 1

:? Go to step 3.

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

3

CHECK ATF TEMPERATURE SENSOR.
1) Turn the ignition switch to OFF.
2) Connect the connectors to transmission and
TCM.
3) Turn the ignition switch to ON and start
engine.
4) Warm up the transmission until the ATF
temperature exceeds 80°C (176°F).

NOTE:
If the ambient temperature is below 0°C (32°F),
drive the vehicle until the ATF reaches its oper-
ating temperature.
5) Disconnect the connector from transmis-
sion.
6) Measure the resistance between transmis-
sion connector terminals.

Connector & terminal

(T4) No. 11 — No. 15:

Is the resistance between 300 —
800

:?

Go to step 4.

Go to step 7.

4

CHECK ATF TEMPERATURE SENSOR.
Measure the resistance between transmission
connector terminals.

Connector & terminal

(T4) No. 11 — No. 15:

Does the resistance value
increase while the ATF temper-
ature decreases?

Go to step 5.

Go to step 7.

5

CHECK INPUT SIGNAL FOR TCM USING
SUBARU SELECT MONITOR.
1) Connect the connector to transmission.
2) Connect the Subaru Select Monitor to data
link connector.
3) Turn the ignition switch to ON (engine OFF).
4) Read the data of “ATF temperature sensor”
using Subaru Select Monitor.

Does the ATF temperature
gradually decrease?

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 and poor
contact of ATF
temperature sen-
sor and transmis-
sion connector.

Go to step 6.

6

CHECK POOR CONTACT.

Is there poor contact in ATF
temperature sensor circuit?

Repair the poor
contact.

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