Subaru Legacy (2005 year). Manual - part 560

4AT(diag)-77

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

7

CHECK HIGH CLUTCH DUTY SOLENOID (IN 
TRANSMISSION).
1) Remove the transmission connector from 
bracket.
2) Drain the ATF.

CAUTION:

Do not drain ATF until it cools down.

3) Remove the oil pan, and disconnect the 
control valve body connector.
4) Measure the resistance between high 
clutch duty solenoid connector and transmis-
sion ground.

Connector & terminal

(AT3) No. 3 — Transmission ground:

Is the resistance 2.0 — 6.0 

Ω? Go to step 8.

Replace the con-
trol valve body. 
<Ref. to 4AT-62, 
Control Valve 
Body.>

8

CHECK HARNESS CONNECTOR BETWEEN 
HIGH CLUTCH DUTY SOLENOID AND 
TRANSMISSION.
Measure the resistance of harness between 
high clutch duty solenoid and transmission 
connector.

Connector & terminal

(T4) No. 7 — (AT3) No. 3:

Is the resistance less than 1 
Ω?

Go to step 9.

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

9

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

Connector & terminal

(T4) No. 7 — Transmission ground:

Is the resistance more than 1 
M

Ω?

Even if the SPORT 
indicator light is 
blinking, the cir-
cuit has returned 
to normal condi-
tion at this time. A 
temporary poor 
contact of connec-
tor or harness may 
be the cause. 
Repair the har-
ness or connector 
in high clutch duty 
solenoid and 
transmission.

Repair the short 
circuit of harness 
between high 
clutch duty sole-
noid and transmis-
sion connector.

Step

Check

Yes

No

4AT(diag)-78

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

T: DTC P0768 SHIFT SOLENOID “D” ELECTRICAL

DTC DETECTING CONDITION:
The output signal circuit of low & reverse duty solenoid is open or shorted.
TROUBLE SYMPTOM:
Gear is not changed.
WIRING DIAGRAM:

Step

Check

Yes

No

1

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

Connector & terminal

(B55) No. 7 — (B11) No. 6:

Is the resistance less than 1 
Ω?

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

(B55) No. 7 — Chassis ground:

Is the resistance more than 1 
M

Ω?

Go to step 3.

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

3

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

Connector & terminal

(T4) No. 6 — No. 20:

Is the resistance 2.0 — 6.0 

Ω? Go to step 4.

Go to step 7.

AT-01490

7

B55

B11

AT3

T4

TCM

B11

1

2

3 4

5

6 7

8

9

13

14 15

20

19

17

16

10

11 12

18

16

B55

AT3

1

2

7

8

9

5

6

3

4

10 11 12

19 20 21

29 30 31

13 14 15 16 17

27 28

18

22 23 24 25 26

1

3

4 5 6

2

TRANSMISSION

LOW & REVERSE
DUTY
SOLENOID

4AT(diag)-79

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

4

CHECK OUTPUT SIGNAL EMITTED FROM 
TCM USING SUBARU SELECT MONITOR.
1) Connect all the connectors.
2) Connect the Subaru Select Monitor to data 
link connector.
3) Start the engine, and turn the Subaru 
Select Monitor power switch to ON.
4) Warm-up the transmission until the ATF 
temperature exceeds approx. 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) Stop the engine and turn the ignition switch 
to ON (engine OFF).
6) Shift the select lever to “N” range.
7) Read the data of low & reverse duty sole-
noid using Subaru Select Monitor.
• Low & reverse duty solenoid is indicated in 
“%”.

Is the value 100%?

Go to step 5.

Go to step 6.

5

CHECK OUTPUT SIGNAL EMITTED FROM 
TCM USING SUBARU SELECT MONITOR.
1) Lift-up the vehicle.

NOTE:

Raise all wheels off floor.

2) Shift the select lever to manual mode, and 
then hold it on 1st. Slowly increase the vehicle 
speed up to 15 km/h (9 MPH), and then return 
the accelerator pedal.

NOTE:

The speed difference between front and rear
wheels may light the ABS warning light or VDC
warning light, but this indicates no malfunction.
When AT control diagnosis is finished, perform
the ABS memory clearance procedure or VDC
memory clearance procedure of on-board diag-
nostics system. <Ref. to ABS(diag)-26, Clear
Memory Mode.> <Ref. to VDC(diag)-25, Clear
Memory Mode.>

3) Read the data of low & reverse duty sole-
noid.

Is the value 55%?

Even if the SPORT 
indicator light is 
blinking, the cir-
cuit has returned 
to normal condi-
tion at this time. A 
temporary poor 
contact of connec-
tor or harness may 
be the cause. 
Repair the har-
ness or connector 
in TCM and trans-
mission.

Go to step 6.

6

CHECK POOR CONTACT.

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

Repair the poor 
contact.

Replace the TCM. 
<Ref. to 4AT-66, 
Transmission Con-
trol Module 
(TCM).>

Step

Check

Yes

No

4AT(diag)-80

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

7

CHECK LOW & REVERSE DUTY SOLENOID 
(IN TRANSMISSION).
1) Remove the transmission connector from 
bracket.
2) Drain the ATF.

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

(AT3) No. 1 — Transmission ground:

Is the resistance 2.0 — 6.0 

Ω? Go to step 8.

Replace the con-
trol valve body. 
<Ref. to 4AT-62, 
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 
connector.

Connector & terminal

(T4) No. 6 — (AT3) No. 1:

Is the resistance less than 1 
Ω?

Go to step 9.

Repair the 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 more than 1 
M

Ω?

Even if the SPORT 
indicator light is 
blinking, the cir-
cuit has returned 
to normal condi-
tion at this time. A 
temporary poor 
contact of connec-
tor or harness may 
be the cause. 
Repair the har-
ness or connector 
in low & reverse 
duty solenoid and 
transmission.

Repair the short 
circuit of harness 
between low & 
reverse brake 
solenoid and 
transmission con-
nector.

Step

Check

Yes

No