Subaru Legacy IV (2008 year). Service manual — part 544

EN(H6DO)(diag)-149

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

AG:DTC P0123 THROTTLE/PEDAL POSITION SENSOR/SWITCH “A” CIRCUIT

HIGH

DTC DETECTING CONDITION:
• Immediately at fault recognition
• GENERAL DESCRIPTION <Ref. to GD(H6DO)-44, DTC P0123 THROTTLE/PEDAL POSITION SEN-
SOR/SWITCH “A” CIRCUIT HIGH, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
• Improper idling
• Engine stalls.
• Poor driving performance

CAUTION:
After repair or replacement of faulty parts, perform Clear Memory Mode <Ref. to EN(H6DO)(diag)-52,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(H6DO)(diag)-44, PROCEDURE,
Inspection Mode.>.
WIRING DIAGRAM:

1 2 3 4
5 6 7 8
9 10 11 12

13 14 15 16

B20

1 2 3 4 5 6

E57

1 2 3 4
5 6 7 8

B122

1 2

7 8

3
4

5
6

B362

36

52

34

35

37

E

E2

B21

E

A5

C21

C1

A29

19

E1

B20

A18

C6

A28

6

4

15

*

*

B122

16

E

38

39

20

D5

D4

A19

D7

D1

A3

D2

D3

3

E57

ELECTRONIC THROTTLE

CONTROL

2

1

5

B134

B362

5

7

6

A:

B137

B136

D:

C:

ECM

*

: TERMINAL No. OPTIONAL ARRANGEMENT

E

SBF-7

BATTERY

ELECTRONIC
THROTTLE
CONTROL RELAY

MAIN RELAY

8

6

4

B47

B47

3

4

1

2

5

6

EN-06873

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

B136

C:

5

6

7

8

2

1

9

4

3

10

22 23

11 12 13 14 15

24 25

26

16 17

18 19 20 21

27

28 29

30 31

B137

D:

5

6

7

8

2

1

9

4

3

10

24

22 23

25

11 12 13 14 15

26 27

28

16 17

18 19 20 21

33 34

29

32

30 31

B134

A:

B21

1 2 3 4 5 6 7 8 9 10 11

12 13 14 15 16 17 18 19 20 21 22
23 24 25 26 27 28 29 30 31 32 33

34

35

42

43

36

37

38

39

48

49

50

51

52

53

54

40

41

44

45

46

47

EN(H6DO)(diag)-150

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

Step

Check

Yes

No

1

CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
electronic throttle control.
3) Measure the resistance of harness between
ECM and electronic throttle control connector.

Connector & terminal

(B134) No. 18 — (E57) No. 6:
(B134) No. 29 — (E57) No. 3:

Is the resistance less than 1

:? Go to step 2.

Repair the harness
and connector.

NOTE:
In this case, repair
the following item:
• Open circuit in
harness between
ECM and electron-
ic throttle control
connector
• Poor contact of
coupling connector

2

CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL.
1) Connect the connector to ECM.
2) Measure the resistance between electronic
throttle control connector and engine ground.

Connector & terminal

(E57) No. 3 — Engine ground:

Is the resistance less than 5

:? Go to step 3.

Repair the harness
and connector.

NOTE:
In this case, repair
the following item:
• Open circuit of
harness between
ECM and engine
ground
• Poor contact in
ECM connector
• Poor contact of
coupling connector

3

CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL.
1) Turn the ignition switch to ON.
2) Measure the voltage between electronic
throttle control connector and engine ground.

Connector & terminal

(E57) No. 6 (+) — Engine ground (–):

Is the voltage 4.85 V or more?

Repair the short
circuit to power in
the harness
between ECM and
electronic throttle
control connector.

Go to step 4.

4

CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM.
3) Measure the resistance between ECM con-
nectors.

Connector & terminal

(B134) No. 19 — (B134) No. 18:

Is the resistance 1 M

: or

more?

Repair poor con-
tact of the elec-
tronic throttle
control connector.
Replace the elec-
tronic throttle con-
trol if defective.
<Ref. to
FU(H6DO)-13,
Throttle Body.>

Repair the short
circuit to power in
the harness
between ECM and
electronic throttle
control connector.

EN(H6DO)(diag)-151

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

AH:DTC P0125 INSUFFICIENT COOLANT TEMPERATURE FOR CLOSED LOOP

FUEL CONTROL

DTC DETECTING CONDITION:
• Two consecutive driving cycles with fault
• GENERAL DESCRIPTION <Ref. to GD(H6DO)-45, DTC P0125 INSUFFICIENT COOLANT TEMPERA-
TURE FOR CLOSED LOOP FUEL CONTROL, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Engine does not return to idle.

CAUTION:
After repair or replacement of faulty parts, perform Clear Memory Mode <Ref. to EN(H6DO)(diag)-52,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(H6DO)(diag)-44, PROCEDURE,
Inspection Mode.>.

Step

Check

Yes

No

1

CHECK TIRE SIZE.

Is the tire size as specified and
the same size as three other
wheels?

Go to step 2.

Replace the tire.

2

CHECK ENGINE COOLANT.
Check the following items:
• Amount of engine coolant
• Engine coolant freeze
• Contamination of engine coolant

Is the engine coolant normal?

Go to step 3.

Fill or replace the
engine coolant.
<Ref. to
CO(H6DO)-10,
Engine Coolant.>

3

CHECK THERMOSTAT.

Does the thermostat remain
opened?

Replace the ther-
mostat. <Ref. to
CO(H6DO)-13,
Thermostat.>

Replace the
engine coolant
temperature sen-
sor. <Ref. to
FU(H6DO)-20,
Engine Coolant
Temperature Sen-
sor.>

EN(H6DO)(diag)-152

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

AI: DTC P0126 INSUFFICIENT ENGINE COOLANT TEMPERATURE FOR STABLE

OPERATION

DTC DETECTING CONDITION:
• Two consecutive driving cycles with fault
• GENERAL DESCRIPTION <Ref. to GD(H6DO)-47, DTC P0126 INSUFFICIENT ENGINE COOLANT
TEMPERATURE FOR STABLE OPERATION, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
• Hard to start
• Improper idling
• Poor driving performance

CAUTION:
After repair or replacement of faulty parts, perform Clear Memory Mode <Ref. to EN(H6DO)(diag)-52,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(H6DO)(diag)-44, PROCEDURE,
Inspection Mode.>.
WIRING DIAGRAM:

EN-06872

29

34

19

8

B134

ECM

1

2

E2

B21

E8

ENGINE

COOLANT

TEMPERATURE

SENSOR

B134

5

6

7

8

2

1

9

4

3

10

24

22 23

25

11 12 13 14 15

26 27

28

16 17

18 19 20 21

33 34

29

32

30 31

E8

1 2

B21

1 2 3 4 5 6 7 8 9 10 11

12 13 14 15 16 17 18 19 20 21 22
23 24 25 26 27 28 29 30 31 32 33

34

35

42

43

36

37

38

39

48

49

50

51

52

53

54

40

41

44

45

46

47