Subaru Legacy (2005 year). Service 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.>