Subaru Legacy (2005 year). Manual - part 627

5AT(diag)-99

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AG:DTC P1601 TCM DATA COMMUNICATION FAILURE

DTC DETECTING CONDITION:
Communication does not complete between control valve memory box.
TROUBLE SYMPTOM:
Shifting quality malfunction
WIRING DIAGRAM:

Step

Check

Yes

No

1

CHECK POOR CONTACT OF TRANSMIS-
SION CONNECTOR.
Check loose connection on TCM connector 
(B54).

Is there poor contact on con-
nector?

Connect it 
securely.

Go to step 2.

2

CHECK DTC OF TCM.

Is DTC of oil pressure switch 
detected?

Perform the diag-
nosis according to 
DTC.

Go to step 3.

AT-03193

B54

TCM

B54

TRANSMISSION

1 2

7

8

9

5 6

3 4

10 11 12
19 20 21

13

14 15

16

17

18

22

23

24

B11

1 2

5

6 7

8

13

14 15

16

9 10

11 12

3 4

17 18

19 20

6

B11

12

21

11

9

10

T10

8

10

9

1 2 3

6

8 9 10 11 12 13 14

4 5

15 16

T10

7

5AT(diag)-100

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

3

CHECK TCM OUTPUT SIGNAL.
1) Turn the ignition switch to ON. (engine 
OFF)
2) Measure the voltage between TCM con-
nector and chassis ground.

Connector & terminal

(B54) No. 16 (+) — Chassis ground (

−

):

Is the voltage 10 — 13 V?

Go to step 4.

Go to step 5.

4

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 and transmission connector.

Connector & terminal

(B54) No. 12 — (B11) No. 9:
(B54) No. 21 — (B11) No. 10:
(B54) No. 6 — (B11) No. 11:

Is the resistance less than 1 
Ω?

Go to step 5.

Repair the open 
circuit of harness 
between TCM and 
transmission con-
nector, and poor 
contact in connec-
tor.

5

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

Connector & terminal

(B54) No. 12 — Chassis ground:
(B54) No. 21 — Chassis ground:
(B54) No. 6 — Chassis ground:

Is the resistance more than 1 
M

Ω?

Go to step 6.

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

6

CHECK HARNESS CONNECTOR BETWEEN 
TRANSMISSION CONNECTOR AND CON-
TROL VALVE BODY CONNECTOR.
Measure the resistance between transmission 
connector and control valve body connector.

Connector & terminal

(B11) No. 9 — (T10) No. 10:
(B11) No. 10 — (T10) No. 9:
(B11) No. 11 — (T10) No. 8:

Is the resistance less than 1 
Ω?

Go to step 7.

Repair the open 
circuit of harness 
between control 
valve body con-
nector and trans-
mission connector.

7

CHECK HARNESS CONNECTOR BETWEEN 
TRANSMISSION CONNECTOR AND CON-
TROL VALVE BODY CONNECTOR.
Measure the resistance between transmission 
connector and chassis ground.

Connector & terminal

(B11) No. 9 — Chassis ground:
(B11) No. 10 — Chassis ground:
(B11) No. 11 — Chassis ground:

Is the resistance more than 1 
M

Ω?

Go to step 8.

Repair the short 
circuit of harness 
between control 
valve body con-
nector and trans-
mission connector.

8

CHECK POOR CONTACT.

NOTE:

Data communication malfunction is detected
when the malfunction occurred on inspection
area above while transmission assembly is re-
placing or “Clear Memory 2” is performing.
When the repair is performed with following di-
agnosis above, perform the “Clear Memory 2”,
and then recheck that the DTC of TCM data
communication malfunction is not detected.

Is there any open or poor con-
tact of connector (loosing ter-
minal, entering foreign matter, 
damaging connector body)?

Repair the poor 
contact.

Replace the trans-
mission assembly. 
<Ref. to 5AT-38, 
Automatic Trans-
mission Assem-
bly.>

Step

Check

Yes

No

5AT(diag)-101

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

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

WHEEL)

DTC DETECTING CONDITION:
Input signal circuit of TCM is open or shorted.
TROUBLE SYMPTOM:
• Shifting quality malfunction
• Tight corner braking phenomenon is occurred.
WIRING DIAGRAM:

AT-01537

1 2 3 4
5 6 7 8

1 2 3 4

10 11 12
19 20 21

13

5 6

14 15

7

8

9

16

17

18

22

23

24

B54

B55

B:

A:

A:

B:

A:

B:

A:

B:

A16

A7

B11

B12

TCM

B54

B55

1 2

7

8

9

5 6

3 4

10 11 12
19 20 21

13

14 15

16

17

18

22

23

24

B11

B12

REAR VEHICLE

SPEED SENSOR

B18

B5

1 2

5

6 7

8

13

14 15

16

9 10

11 12

3 4

17 18

19 20

E

5AT(diag)-102

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

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 and transmission connector.

Connector & terminal

(B54) No. 16 — (B11) No. 7:
(B55) No. 18 — (B12) No. 5:

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 TRANSMISSION.
Measure the resistance of harness between 
TCM connector and chassis ground.

Connector & terminal

(B54) No. 16 — Chassis ground:
(B55) No. 18 — Chassis ground:

Is the resistance more than 1 
M

Ω?

Go to step 3.

Repair the short 
circuit of harness 
between TCM and 
chassis ground.

3

CHECK TCM POWER SUPPLY OUTPUT.
1) Connect the connector to TCM. (Transmis-
sion connector is disconnected)
2) Turn the ignition switch to ON. (engine 
OFF)
3) Measure the voltage between TCM con-
nector and chassis ground.

Connector & terminal

(B54) No. 16 (+) — Chassis ground (

−

):

Is the voltage 10 — 13 V?

Go to step 4.

Go to step 5.

4

CHECK TURBINE SPEED SENSOR INPUT 
CIRCUIT OF TCM.
Measure the voltage between TCM connector 
terminals.

Connector & terminal

(B55) No. 18 (+) — (B54) No. 19 (

−

):

Is the voltage 4 — 6 V?

Go to step 6.

Go to step 5.

5

CHECK TCM I/O SIGNAL.
Check TCM I/O signal of power supply, ground 
and PVIGN power supply relay.
<Ref. to 5AT(diag)-13, ELECTRICAL SPECIFI-
CATION, Transmission Control Module (TCM) 
I/O Signal.>

Is TCM I/O signal OK?

Replace the TCM. 
<Ref. to 5AT-61, 
Transmission Con-
trol Module 
(TCM).>

Repair the open or 
short circuit for 
power supply and 
ground. Perform 
the diagnosis 
according to DTC 
for PVIGN power 
supply relay.

6

CHECK HARNESS ASSEMBLY (TURBINE 
SPEED SENSOR GROUND).
Check the installing condition of ground con-
necting harness (used for both of turbine 
speed sensor 1, rear vehicle speed sensor).

Is the ground connecting har-
ness installed to transmission 
body correctly, or the harness 
and connector terminals not 
damaged?

Go to step 7.

When the poor 
installation of 
ground connect-
ing harness, install 
it securely.
Replace the trans-
mission assembly 
when the harness 
is damaged. <Ref. 
to 5AT-38, Auto-
matic Transmis-
sion Assembly.>