Subaru Legacy III (2000-2003 year). Service manual — part 172

EN(H4SO)-300

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

CQ:DTC P1711 — ENGINE TORQUE CONTROL SIGNAL #1 CIRCUIT MALFUNC-

TION —

• DTC DETECTING CONDITION:

• Two consecutive driving cycles with fault

• TROUBLE SYMPTOM:

• Excessive shift shock

CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode<Ref. to EN(H4SO)-47, OPER-
ATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4SO)-40, OPERATION, Inspection
Mode.> .
• WIRING DIAGRAM:

EN-01140

15

B136 ECM

TCM

B56

B136

5 6

7

2

1

9

8

4

3

23

21 22

24

10 11 12 13 14

25 26

15 16 17

18 19 20

B56

1 2

7

8

9

5 6

3 4

10 11 12
19 20 21

13

14 15

16

17

18

22

23

24

EN(H4SO)-301

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

Step

Value

Yes

No

1

CHECK INPUT SIGNAL FOR ECM.
1) Turn ignition switch to ON.
2) Measure voltage between ECM and chas-

sis ground.

Connector & terminal

(B136) No. 1 (+) — Chassis ground (

−−−−

):

Does the measured value exceed the spec-
ified value?

4.5 V

Go to step 2.

Go to step 4.

2

CHECK INPUT SIGNAL FOR ECM.
Measure voltage between ECM and chassis
ground.

Connector & terminal

(B136) No. 1 (+) — Chassis ground (

−−−−

):

Does the measured value exceed the specified
value?

10 V

Repair battery
short circuit in har-
ness between
ECM and TCM
connector.

Go to step 3.

3

CHECK POOR CONTACT.
Check poor contact in ECM connector.
Is there poor contact in ECM connector?

There is poor contact.

Repair poor con-
tact in ECM con-
nector.

Contact SUBARU
distributor service.

NOTE:
Inspection by DTM
is required, be-
cause probable
cause is deteriora-
tion of multiple
parts.

4

CHECK HARNESS BETWEEN ECM AND
TCM CONNECTOR.
1) Turn ignition switch to OFF.
2) Disconnect connectors from ECM and

TCM.

3) Measure resistance of harness between

ECM and TCM connector.

Connector & terminal

(B136) No. 1 — (B56) No. 5:

Is the measured value less than the speci-
fied value?

1

Ω

Go to step 5.

Repair open circuit
in harness
between ECM and
TCM connector.

5

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

Connector & terminal

(B136) No. 1 — Chassis ground:

Does the measured value exceed the specified
value?

1 M

Ω

Go to step 6.

Repair ground
short circuit in har-
ness between
ECM and TCM
connector.

6

CHECK POOR CONTACT.
Check poor contact in TCM connector.
Is there poor contact in TCM connector?

There is poor contact.

Repair poor con-
tact in TCM con-
nector.

Replace TCM.
<Ref. to AT-76,
Transmission Con-
trol Module
(TCM).>

EN(H4SO)-302

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

CR:DTC P1712 — ENGINE TORQUE CONTROL SIGNAL #2 CIRCUIT MALFUNC-

TION —

• DTC DETECTING CONDITION:

• Two consecutive driving cycles with fault

• TROUBLE SYMPTOM:

• Excessive shift shock

CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode<Ref. to EN(H4SO)-47, OPER-
ATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4SO)-40, OPERATION, Inspection
Mode.> .
• WIRING DIAGRAM:

EN-01141

18

14

B136 ECM

TCM

B56

B136

5 6

7

2

1

9

8

4

3

23

21 22

24

10 11 12 13 14

25 26

15 16 17

18 19 20

B56

1 2

7

8

9

5 6

3 4

10 11 12
19 20 21

13

14 15

16

17

18

22

23

24

EN(H4SO)-303

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

Step

Value

Yes

No

1

CHECK INPUT SIGNAL FOR ECM.
1) Turn ignition switch to ON.
2) Measure voltage between ECM and chas-

sis ground.

Connector & terminal

(B136) No. 18 (+) — Chassis ground (

−−−−

):

Does the measured value exceed the spec-
ified value?

4.5 V

Go to step 2.

Go to step 4.

2

CHECK INPUT SIGNAL FOR ECM.
Measure voltage between ECM and chassis
ground.

Connector & terminal

(B136) No. 18 (+) — Chassis ground (

−−−−

):

Does the measured value exceed the specified
value?

10 V

Repair battery
short circuit in har-
ness between
ECM and TCM
connector.

Go to step 3.

3

CHECK POOR CONTACT.
Check poor contact in ECM connector.
Is there poor contact in ECM connector?

There is poor contact.

Repair poor con-
tact in ECM con-
nector.

Contact SUBARU
distributor service.

NOTE:
Inspection by DTM
is required, be-
cause probable
cause is deteriora-
tion of multiple
parts.

4

CHECK HARNESS BETWEEN ECM AND
TCM CONNECTOR.
1) Turn ignition switch to OFF.
2) Disconnect connectors from ECM and

TCM.

3) Measure resistance of harness between

ECM and TCM connector.

Connector & terminal

(B136) No. 18 — (B56) No. 14:

1

Ω

Go to step 5.

Repair open circuit
in harness
between ECM and
TCM connector.

5

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

Connector & terminal

(B136) No. 18 — Chassis ground:

Is the measured value less than the specified
value?

10

Ω

Go to step 6.

Repair ground
short circuit in har-
ness between
ECM and TCM
connector.

6

CHECK POOR CONTACT.
Check poor contact in TCM connector.
Is there poor contact in TCM connector?

There is poor contact.

Repair poor con-
tact in TCM con-
nector.

Replace TCM.
<Ref. to AT-76,
Transmission Con-
trol Module
(TCM).>