Subaru Legacy IV (2008 year). Service manual — part 714

4AT(diag)-77

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

4

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

Connector & terminal

(B54) No. 15 — Chassis ground:

Is the resistance 1 M

: or

more?

Go to step 5.

Repair the short
circuit of harness
between TCM and
rear vehicle speed
sensor connector.

5

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

Connector & terminal

(B54) No. 26 — Chassis ground:

Is the resistance 1 M

: or

more?

Go to step 6.

Repair the short
circuit of harness
between TCM and
rear vehicle speed
sensor connector.

6

PREPARE OSCILLOSCOPE.

Do you have an oscilloscope?

Go to step 8.

Go to step 7.

7

CHECK INPUT SIGNAL FOR TCM.
1) Connect the connectors to TCM and trans-
mission.
2) Lift up the vehicle.
3) Start the engine and set vehicle in 20 km/h
(12 MPH) condition.

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.>
4) Measure the AC voltage between TCM con-
nector terminals.

Connector & terminal

(B54) No. 26 (+) — No. 15 (–):

Is the voltage approx. 2 V or
more?

Go to step 9.

Replace the rear
vehicle speed sen-
sor.

8

CHECK INPUT SIGNAL FOR TCM USING
OSCILLOSCOPE.
1) Connect the connectors to TCM and trans-
mission.
2) Lift up the vehicle.
3) Set the oscilloscope to TCM connector ter-
minals.

Connector & terminal

Positive probe; (B54) No. 26:
Ground lead; (B54) No. 15:

4) Start the engine and set vehicle in 20 km/h
(12 MPH) condition.

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.>
5) Measure the signal voltage indicated on
oscilloscope.

Is the pulse voltage approx. 5 V? Go to step 9.

Replace the rear
vehicle speed sen-
sor.

9

CHECK POOR CONTACT.

Is there poor contact in rear
vehicle speed sensor circuit?

Repair the poor
contact.

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

Step

Check

Yes

No

4AT(diag)-78

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

W: DTC P1707 AT AWD SOLENOID VALVE CIRCUIT MALFUNCTION

DTC DETECTING CONDITION:
Output signal circuit of transfer duty solenoid is open or shorted.
TROUBLE SYMPTOM:
• Tight corner braking phenomenon occurs.
• Front wheel slips on the slippery road.
WIRING DIAGRAM:

AT-04774

B11

1

2

3 4

5

6 7

8

9

13

14 15

20

19

17

16

10

11 12

18

5

B54

B11

AT 2

T4

8

7

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

TCM

CONTROL VALVE BODY

TRANSFER
DUTY
SOLENOID

4AT(diag)-79

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 connector and transmission connector.

Connector & terminal

(B54) No. 5 — (B11) No. 8:

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 connector
between TCM and chassis ground.

Connector & terminal

(B54) No. 5 — 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 TRANSFER DUTY SOLENOID.
Measure the resistance between transmission
connector and transmission terminals.

Connector & terminal

(T4) No. 8 — 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) Turn the ignition switch to ON (engine OFF)
and run the Subaru Select Monitor.
4) Shift the select lever to the “N” range, and
fully close the throttle pedal. (Vehicle speed is 0
km/h (0 MPH))
5) Read the data of “AWD Duty Ratio” using
Subaru Select Monitor.
Transfer duty solenoid is indicated in “%”.

Is the value approx. 5%?

Go to step 5.

Go to step 6.

5

CHECK OUTPUT SIGNAL FROM TCM US-
ING SUBARU SELECT MONITOR.
1) Shift the select lever to “D” range.
2) Read the data of “AWD Duty Ratio” using
Subaru Select Monitor.
Transfer duty solenoid is indicated in “%”.

Is the measured value approx.
18 — 35%?

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 TCM and
transmission.

Go to step 6.

6

CHECK POOR CONTACT.

Is there poor contact in transfer
duty solenoid circuit?

Repair the poor
contact.

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

4AT(diag)-80

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

X: DTC P1718 CAN COMMUNICATION CIRCUIT

NOTE:
Refer to “Body Integrated Unit” for diagnosis of P1718. <Ref. to LAN(diag)-2, Basic Diagnostic Procedure.>

7

CHECK TRANSFER DUTY SOLENOID (IN
TRANSMISSION).
1) Lift up the vehicle.
2) Drain the automatic transmission fluid.

CAUTION:
Do not drain ATF until it cools down.
3) Remove the extension case, and discon-
nect the connector from transfer duty solenoid.
4) Measure the resistance between transfer
duty solenoid connector and transmission
ground.

Connector & terminal

(AT2) No. 7 — 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
TRANSFER DUTY SOLENOID AND TRANS-
MISSION.
Measure the resistance of harness between
transfer duty solenoid and transmission con-
nector.

Connector & terminal

(T4) No. 8 — (AT2) No. 7:

Is the resistance less than 1

:? Go to step 9.

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

9

CHECK HARNESS CONNECTOR BETWEEN
TRANSFER DUTY SOLENOID AND TRANS-
MISSION.
Measure the resistance of harness between
transmission connector and transmission
ground.

Connector & terminal

(T4) No. 8 — 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 poor
contact in the
transfer duty sole-
noid and transmis-
sion.

Repair short cir-
cuit of the harness
between the trans-
fer duty solenoid
and transmission
connector.

Step

Check

Yes

No