Subaru Legacy IV (2008 year). Manual - part 713

4AT(diag)-73

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

6

CHECK POOR CONTACT.

Is there poor contact in the low 
& reverse duty solenoid circuit?

Repair the poor 
contact.

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

7

CHECK LOW & REVERSE BRAKE DUTY SO-
LENOID (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 & 
reverse duty solenoid connector and transmis-
sion ground.

Connector & terminal

(AT2) No. 1 — 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 & REVERSE 
DUTY SOLENOID.
Measure the resistance of harness between low 
& reverse duty solenoid and transmission con-
nector.

Connector & terminal

(T4) No. 6 — (AT2) No. 1:

Is the resistance less than 1 

:? Go to step 9.

Repair open circuit 
of harness 
between low & 
reverse duty sole-
noid and transmis-
sion connector.

9

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

Connector & terminal

(T4) No. 6 — 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 har-
ness or connector 
in low & reverse 
duty solenoid and 
transmission.

Repair the short 
circuit of the har-
ness between the 
low & reverse duty 
solenoid and the 
transmission con-
nector.

Step

Check

Yes

No

4AT(diag)-74

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

U: DTC P0801 REVERSE INHIBIT CONTROL CIRCUIT

DTC DETECTING CONDITION:
Shift lock solenoid malfunction, open or short reverse inhibitor control circuit
TROUBLE SYMPTOM:
• Gear is shifted from “N” range to “P” range during driving at 20 km/h (12 MPH) or more.
• Gear cannot be shifted from “N” range to “R” range.
WIRING DIAGRAM:

Step

Check

Yes

No

1

CHECK SHIFT LOCK SOLENOID.
1) Start the integrated unit by force, and check 
the operation of shift lock solenoid. <Ref. to 
LAN(diag)-12, READ DIAGNOSTIC TROUBLE 
CODE (DTC), OPERATION, Subaru Select 
Monitor.>
2) Operate AT select lever without depressing 
the brake pedal.

Does the AT select lever oper-
ate?

Go to step 2.

Go to step 3.

2

CHECK OUTPUT SIGNAL OF INTEGRATED 
UNIT.
1) Display the following items using Subaru 
Select Monitor.
• Key-lock warning SW
• Shift Position
• P  SW
• 'Stop Light Switch
2) Step on the brake and shift the AT select 
lever to “P” range.

Do the units of measure of 
items displayed change?

Go to step 3.

Check the circuits 
of the items whose 
values do not 
change.

3

CHECK HARNESS CONNECTOR BETWEEN 
BODY INTEGRATED UNIT AND SHIFT LOCK 
SOLENOID.
Measure the harness resistance between the 
body integrated unit and chassis ground.

Connector & terminal

(B280) No. 6 — Chassis ground:

Is the resistance 1 M

: or 

more?

Go to step 4.

Repair the short 
circuit of harness 
between body inte-
grated unit and 
shift lock solenoid 
connector.

6

E

B116

B116

3
4

B280

B280

1 2

3 4 5

6 7 8 9 10 11 12

5

4

6 7

8

2

1

9

3

10

22

23

11 12 13 14 15

24 25

26 27

16 17 18

28 29

19 20

21

30

AT-04340

BODY INTEGRATED UNIT

SHIFT LOCK 
SOLENOID

4AT(diag)-75

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

4

CHECK HARNESS BETWEEN SHIFT LOCK 
SOLENOID AND CHASSIS GROUND TERMI-
NAL.
Measure the resistance of harness between 
shift lock solenoid and chassis ground.

Connector & terminal

(B116) No. 4 — Chassis ground:

Is the resistance less than 1 

:? Go to step 5.

Repair the open 
circuit of harness 
between chassis 
ground and shift 
lock solenoid con-
nector.

5

CHECK SHIFT LOCK SOLENOID.
Measure the resistance of shift lock solenoid 
terminals.

Connector & terminal

(B116) No. 3 — No. 4:

Is the resistance 12 — 18 

:?

Go to step 6.

Replace the shift 
lock solenoid.

6

CHECK OUTPUT SIGNAL OF BODY INTE-
GRATED UNIT.
1) Connect all connectors.
2) Turn the ignition switch to ON.
3) Shift the AT select lever to “D” range.
4) Measure the voltage between body inte-
grated unit and chassis ground.

Connector & terminal

(B280) No. 6 (+) — Chassis ground (–):

Is the voltage 10.5 V or more?

Go to step 7.

Go to step 8.

7

CHECK OUTPUT SIGNAL OF BODY INTE-
GRATED UNIT.
1) Lift up the vehicle.
2) Start the engine.
3) Shift the select lever to “D” range and slowly 
increase vehicle speed to over 20 km/h (12 
MPH).

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 voltage between body inte-
grated unit and chassis ground.

Connector & terminal

(B280) No. 6 (+) — Chassis ground (–):

Is the voltage less than 1 V?

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 
reverse inhibitor 
control circuit.

Go to step 8.

8

CHECK POOR CONTACT.

Is there poor contact in the 
reverse inhibitor control circuit?

Repair the poor 
contact.

Replace the body 
integrated unit. 
<Ref. to SL-56, 
Body Integrated 
Unit.>

Step

Check

Yes

No

4AT(diag)-76

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

V: DTC P1706 AT VEHICLE SPEED SENSOR CIRCUIT MALFUNCTION (REAR 

WHEEL)

DTC DETECTING CONDITION:
Input signal circuit of TCM is open or shorted.
TROUBLE SYMPTOM:
No lock up or tight corner braking phenomenon is occurred.
WIRING DIAGRAM:

Step

Check

Yes

No

1

CHECK IGNITION POWER SUPPLY CIR-
CUIT.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from rear vehicle 
speed sensor.
3) Turn the ignition switch to ON.
4) Measure the ignition power supply voltage 
between rear vehicle speed sensor connector 
and transmission ground.

Connector & terminal

(AT13) No. 3 (+) — Transmission ground 
(–):

Is the voltage 10 V or more?

Go to step 2.

Check harness 
between rear vehi-
cle speed sensor 
and battery for 
open circuit, short 
or poor contact. 
Repair the harness 
if required.

2

CHECK HARNESS CONNECTOR BETWEEN 
TCM AND TRANSMISSION.
1) Turn the ignition switch to OFF.
2) Measure the resistance of harness between 
TCM connector and rear vehicle speed sensor 
connector.

Connector & terminal

(B54) No. 15 — (AT13) No. 1:

Is the resistance less than 1 

:? Go to step 3.

Repair the open 
circuit or poor con-
tact of the connec-
tor in harness 
between TCM and 
rear vehicle speed 
sensor connector.

3

CHECK HARNESS CONNECTOR BETWEEN 
TCM AND TRANSMISSION.
Measure the resistance of harness between 
TCM connector and rear vehicle speed sensor 
connector.

Connector & terminal

(B54) No. 26 — (AT13) No. 2:

Is the resistance less than 1 

:? Go to step 4.

Repair the open 
circuit or poor con-
tact of the connec-
tor in harness 
between TCM and 
rear vehicle speed 
sensor connector.

15

26

B11

AT13

T4

9

17

13

3

1

2

B54

E

MAIN SBF

SBF-6

No.12

B11

AT13

1 2 3

TCM

B54

AT-04341

1 2

5

6 7

8

13

14 15

16

9 10

11 12

3 4

17 18

19 20

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

BATTERY

IGNITION
SWITCH

REAR VEHICLE 
SPEED SENSOR