Subaru Legacy IV (2008 year). Manual - part 172

EN(H4SO)(diag)-291

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

DH:DTC P2128 THROTTLE/PEDAL POSITION SENSOR/SWITCH “E” CIRCUIT 

HIGH INPUT

DTC DETECTING CONDITION:
• Immediately at fault recognition
• GENERAL DESCRIPTION <Ref. to GD(H4SO)-192, DTC P2128 THROTTLE/PEDAL POSITION SEN-
SOR/SWITCH “E” CIRCUIT HIGH INPUT, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
• Improper idling
• Poor driving performance

CAUTION:
After repair or replacement of faulty parts, perform Clear Memory Mode <Ref. to EN(H4SO)(diag)-50,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(H4SO)(diag)-41, PROCEDURE,
Inspection Mode.>.
WIRING DIAGRAM:

EN-06844

B315

E

C:

ECM

B136

B137

D:

B83

B315

*

*

4

6

5

1

3

2

D1

D2

1 2 3 4 5 6

B21

E2

D3

B122

1 2 3 4
5 6 7 8

B21

1 2 3 4

12 13 14 15

5 6 7 8

16 17 18 19

9 10 11

20 21 22

23 24 25 26 27 28 29 30 31 32 33

35

34

37

36

39

38

41

40

43

42

44

45

47

46

49

48

51

50

53

52

54

B137

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

B136

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

35

B135

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

29 30 31

32 33

34 35

B:

B134

A:

C:

D:

B83

A5

B: B135

A: B134

D7

36

34

52

35

37

B122

ACCELERATOR 

PEDAL 

POSITION

SENSOR

E

*

*

 : TERMINAL No. OPTIONAL 
 ARRANGEMENT

*

B21

B23

B29

B22

B31

B30

C6

8

5

6

10 11 12 13 14 15

7

2

1

3

4

16

30

19 20

22

28 29

9

17

18

25

21

23 24

32

31

26 27
33 34

EN(H4SO)(diag)-292

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

Step

Check

Yes

No

1

CHECK HARNESS BETWEEN ECM AND AC-
CELERATOR PEDAL POSITION SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and 
accelerator pedal position sensor.
3) Measure the resistance of harness between 
ECM and accelerator pedal position sensor 
connector.

Connector & terminal

(B135) No. 31 — (B315) No. 3:
(B135) No. 30 — (B315) No. 2:

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 of
harness between
the ECM and ac-
celerator pedal po-
sition sensor
connector.
• Poor contact in
joint connector

2

CHECK HARNESS BETWEEN ECM AND AC-
CELERATOR PEDAL POSITION SENSOR.
1) Connect the connector to ECM.
2) Measure the resistance between accelera-
tor pedal position sensor connector and chassis 
ground.

Connector & terminal

(B315) No. 2 — Chassis ground:

Is the resistance less than 1 

:? 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 AC-
CELERATOR PEDAL POSITION SENSOR.
1) Turn the ignition switch to ON.
2) Measure the voltage between accelerator 
pedal position sensor connector and chassis 
ground.

Connector & terminal

(B315) No. 3 (+) — Chassis ground (–):

Is the voltage 4.85 V or more?

Repair the short 
circuit of harness 
to power supply 
between ECM and 
accelerator pedal 
position sensor 
connector.

Go to step 4.

4

CHECK HARNESS BETWEEN ECM AND AC-
CELERATOR PEDAL POSITION SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM.
3) Measure the resistance between ECM con-
nectors.

Connector & terminal

(B135) No. 22 — (B135) No. 31:

Is the resistance 1 M

: or 

more?

Repair the poor 
contact of acceler-
ator pedal position 
sensor connector. 
Replace the accel-
erator pedal if 
defective. <Ref. to 
SP(H4SO)-3, 
Accelerator 
Pedal.>

Repair the short 
circuit of harness 
to power supply 
between ECM and 
accelerator pedal 
position sensor 
connector.

EN(H4SO)(diag)-293

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

DI: DTC P2135 THROTTLE/PEDAL POSITION SENSOR/SWITCH “A”/“B” VOLTAGE 

CORRELATION

DTC DETECTING CONDITION:
• Immediately at fault recognition
• GENERAL DESCRIPTION <Ref. to GD(H4SO)-194, DTC P2135 THROTTLE/PEDAL POSITION SEN-
SOR/SWITCH “A”/“B” VOLTAGE CORRELATION, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
• Improper idling
• Poor driving performance

CAUTION:
After repair or replacement of faulty parts, perform Clear Memory Mode <Ref. to EN(H4SO)(diag)-50,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(H4SO)(diag)-41, PROCEDURE,
Inspection Mode.>.
WIRING DIAGRAM:

EN-06838

SBF-7

B134

A:

B137

B136

D:

B362

C:

E

C1

C21

D4

D5

A29

A19

D3

D7

D1

D2

A5

A28

A18

C6

ECM

5

8

7

6

B362

B47

B21

E57

B122

1 2

7 8

3
4

5
6

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

34 35

36 37 38 39 40 41

48 49

50 51 52 53 54

42 43

44 45

46 47

26 27 28 29 30 31 32 33

1 2 3 4
5 6 7 8

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

2

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

7

32 33 34 35

B134

A:

B136

C:

B137

D:

BATTERY

ELECTRONIC 
THROTTLE 
CONTROL RELAY

MAIN RELAY

1 2 3 4 5 6

E2

B21

B122

E

E

E

39

20

E57

4

6

1

2

3

5

34

35

36

37

52

*
*

ELECTRONIC 
THROTTLE CONTROL

: TERMINAL No. OPTIONAL ARRANGEMENT

*

18

17

38

19

8

5

6

10 11 12 13 14 15

7

2

1

3

4

16

30

19 20

22

28 29

9

17

18

25

21

23 24

32

31

26 27
33 34

3

4

1

2

5

6

6

4

B47

EN(H4SO)(diag)-294

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 between ECM and 
chassis ground.

Connector & terminal

(B134) No. 19 — Chassis ground:
(B134) No. 18 — Chassis ground:
(B134) No. 18 — (B136) No. 6:
(B134) No. 28 — Chassis ground:

Is the resistance 1 M

: or 

more?

Go to step 2.

Repair the short 
circuit to ground in 
harness between 
ECM and elec-
tronic throttle con-
trol connector.

2

CHECK SHORT CIRCUIT INSIDE THE ECM.
1) Connect the connector to ECM.
2) Measure the resistance between electronic 
throttle control connector and engine ground.

Connector & terminal

(E57) No. 6 — Engine ground:
(E57) No. 4 — Engine ground:

Is the resistance 1 M

: or 

more?

Go to step 3.

Repair the short 
circuit to ground in 
harness between 
ECM and elec-
tronic throttle con-
trol connector. 
Replace the ECM if 
defective. <Ref. to 
FU(H4SO)-39,
Engine Control 
Module (ECM).>

3

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

Connector & terminal

(B134) No. 18 — (E57) No. 6:
(B134) No. 28 — (E57) No. 4:
(B134) No. 29 — (E57) No. 3:

Is the resistance less than 1 

:? Go to step 4.

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

4

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 5.

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

5

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 (–):
(E57) No. 4 (+) — 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 6.