Subaru Legacy IV (2008 year). Manual — part 708

4AT(diag)-53

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

H: DTC P0725 ENGINE SPEED INPUT CIRCUIT

DTC DETECTING CONDITION:
Engine speed input signal circuit is open or shorted.
TROUBLE SYMPTOM:
• No lock-up occurs. (After engine is warmed up)
• ATF temperature warning light remains ON when the vehicle speed is “0”.
WIRING DIAGRAM:

AT-04333

11

B136

ECM

B55

TCM

22

B136

B55

16

10 11 12 13 14 15

25

24

30

9

8

7

17 18 19 20
28

21 22 23

29

32

31

1

2

3

4

5

6

27

26

33 34 35

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

4AT(diag)-54

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

I:

DTC P0731 GEAR 1 INCORRECT RATIO

NOTE:
Refer to DTC P0736 for diagnostic procedure. <Ref. to 4AT(diag)-55, DTC P0736 REVERSE INCORRECT
RATIO, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>

J: DTC P0732 GEAR 2 INCORRECT RATIO

NOTE:
Refer to DTC P0736 for diagnostic procedure. <Ref. to 4AT(diag)-55, DTC P0736 REVERSE INCORRECT
RATIO, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>

K: DTC P0733 GEAR 3 INCORRECT RATIO

NOTE:
Refer to DTC P0736 for diagnostic procedure. <Ref. to 4AT(diag)-55, DTC P0736 REVERSE INCORRECT
RATIO, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>

L: DTC P0734 GEAR 4 INCORRECT RATIO

NOTE:
Refer to DTC P0736 for diagnostic procedure. <Ref. to 4AT(diag)-55, DTC P0736 REVERSE INCORRECT
RATIO, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>

Step

Check

Yes

No

1

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

Connector & terminal

(B55) No. 11 — (B136) No. 22:

Is the resistance less than 1

:? Go to step 2.

Repair the open
circuit of harness
between TCM and
ECM connector.

2

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

Connector & terminal

(B55) No. 11 — Chassis ground:

Is the resistance 1 M

: or

more?

Go to step 3.

Repair the short
circuit of harness
between TCM and
ECM connector.

3

CHECK INPUT SIGNAL FOR TCM USING
SUBARU SELECT MONITOR.
1) Connect the connectors to TCM and ECM.
2) Connect the Subaru Select Monitor to data
link connector.
3) Start the engine, and run the Subaru Select
Monitor.
4) Idle the engine.
5) Read the data of “Engine Speed” using Sub-
aru Select Monitor.
• Display shows engine speed signal value
sent from ECM.

Is the revolution value same as
the tachometer reading shown
on the combination meter?

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 the TCM
and ECM.

Go to step 4.

4

CHECK POOR CONTACT.

Is there poor contact in engine
speed signal circuit?

Repair the poor
contact.

Go to step 5.

5

CONFIRM DTC P0725.
Replace the ECM with a new part.

Does the DTC appear again,
after the memory has been
cleared?

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

Replace the ECM.

4AT(diag)-55

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

M: DTC P0736 REVERSE INCORRECT RATIO

DTC DETECTING CONDITION:
Vehicle sensor, torque converter turbine speed sensor or control valve malfunction
TROUBLE SYMPTOM:
• Shift point is too high or too low.
• Excessive shift shock
• Tight corner braking phenomenon occurs.
• Gear is not shifted to reverse.
• Gear position is held by fail safe function.

Step

Check

Yes

No

1

CHECK ACCELERATOR PEDAL POSITION
SENSOR.
1) Connect the Subaru Select Monitor to data
link connector.
2) Turn the ignition switch to ON.
3) Read the value of “Accel. opening angle” on
Subaru Select Monitor display.

Does the value of “Accel. open-
ing angle” change from 0% to
100% smoothly when throttle is
operated from fully closed to
fully open?

Go to step 2.

Check the acceler-
ator pedal position
sensor circuit.

2

CHECK FRONT VEHICLE SPEED SENSOR.
1) Lift up the vehicle.
2) Start the engine.
3) Shift the select lever to “D” range and slowly
increase vehicle speed.

NOTE:
The speed difference between front and rear
wheels may illuminate the ABS warning light,
but this indicates no malfunction. When AT con-
trol diagnosis is finished, perform the ABS or
VDC clear memory of on-board diagnostics
system. <Ref. to ABS(diag)-20, Clear Memory
Mode.> <Ref. to VDC(diag)-23, Clear Memory
Mode.>

Does the vehicle speed dis-
played by Subaru Select Moni-
tor roughly correspond with
vehicle speed indicated by the
combination meter?

Go to step 3.

Check the front
vehicle speed sen-
sor circuit.

3

CHECK TORQUE CONVERTER TURBINE
SPEED SENSOR.
1) Shift the select lever to “P” or “N” range.
2) Idle the engine.

Does the value of torque con-
verter turbine speed sensor dis-
played by Subaru Select
Monitor roughly correspond
with the value of tachometer in
combination meter?

There are malfunc-
tions in TCM, TCM
connector poor
contact, or trans-
mission assembly
mechanical mal-
function.

Check the torque
converter turbine
speed sensor cir-
cuit.

4AT(diag)-56

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

N: DTC P0741 TORQUE CONVERTER CLUTCH CIRCUIT PERFORMANCE OR

STUCK OFF

DTC DETECTING CONDITION:
• Lock up clutch malfunction
• Sticky valve
TROUBLE SYMPTOM:
No lock-up occurs.

Step

Check

Yes

No

1

CHECK LOCK-UP DUTY SOLENOID CIR-
CUIT.
Diagnose according to DTC P0743 procedure.

Is there any fault?

Repair or replace
the lock up duty
solenoid circuit.

Go to step 2.

2

CHECK INHIBITOR SWITCH CIRCUIT.
Diagnose according to DTC P0705 procedure.

Is there any fault?

Repair or replace
the inhibitor switch
circuit.

Go to step 3.

3

CHECK STOP LIGHT SWITCH CIRCUIT.
Diagnose according to DTC P0719 and P0724
procedures.

Is there any fault?

Repair or replace
the stop light
switch circuit.

Go to step 4.

4

CHECK ATF TEMPERATURE SENSOR CIR-
CUIT.
Diagnose according to DTC P0712 and P0713
procedure.

Is there any fault?

Repair or replace
the ATF tempera-
ture sensor circuit.

Go to step 5.

5

CHECK ACCELERATOR PEDAL POSITION
SENSOR.
1) Connect the Subaru Select Monitor to data
link connector.
2) Turn the ignition switch to ON.
3) Read the value of “Accel. opening angle” on
Subaru Select Monitor display.

Does the value of accelerator
pedal position sensor change
from 0% to 100% smoothly
when throttle is operated from
fully closed to fully open?

Go to step 6.

Check the acceler-
ator pedal position
sensor circuit.

6

CHECK TORQUE CONVERTER TURBINE
SPEED SENSOR.
1) Shift the select lever to “P” or “N” range.
2) Idle the engine.

Does the value of turbine speed
displayed by Subaru Select
Monitor almost correspond with
the value of the tachometer?

Go to step 7.

Check the torque
converter turbine
speed sensor cir-
cuit.

7

CHECK ENGINE SPEED SIGNAL.
Idle the engine.

Does the value of turbine speed
displayed by Subaru Select
Monitor almost correspond with
the value of the tachometer?

There is transmis-
sion assembly
mechanical mal-
function.

Check the engine
speed signal cir-
cuit.