Subaru Legacy IV (2008 year). Manual - part 590

EN(H6DO)(diag)-333

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

EF:DTC P2122 THROTTLE/PEDAL POSITION SENSOR/SWITCH “D” CIRCUIT 

LOW INPUT

DTC DETECTING CONDITION:
• Immediately at fault recognition
• GENERAL DESCRIPTION <Ref. to GD(H6DO)-199, DTC P2122 THROTTLE/PEDAL POSITION SEN-
SOR/SWITCH “D” CIRCUIT LOW 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(H6DO)(diag)-52,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(H6DO)(diag)-44, PROCEDURE,
Inspection Mode.>.
WIRING DIAGRAM:

E

C:

ECM

B136

B137

D:

B83

B315

*

*

4

6

5

1

3

2

B21

B23

B29

B22

B31

B30

A3

D2

B21

E2

D1

1 2 3 4
5 6 7 8

B122

B83

D3

A5

C6

B: B135

A: B134

D7

37

35

34

52

36

B122

B315

1 2 3 4 5 6

*

*

*

E

EN-06883

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

29 30 31

32 33

34 35

B135

B:

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

ACCELERATOR  

PEDAL 

POSITION

SENSOR

: TERMINAL No. OPTIONAL 
 ARRANGEMENT

EN(H6DO)(diag)-334

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 between ECM and 
chassis ground.

Connector & terminal

(B135) No. 21 — Chassis ground:
(B135) No. 23 — Chassis ground:
(B135) No. 23 — (B136) No. 6:

Is the resistance 1 M

: or 

more?

Go to step 2.

Repair the ground 
short circuit of har-
ness between 
ECM and accelera-
tor pedal position 
sensor connector.

2

CHECK SHORT CIRCUIT INSIDE THE ECM.
1) Connect the connector to ECM.
2) Measure the resistance between accelera-
tor pedal position sensor connector and chassis 
ground.

Connector & terminal

(B315) No. 5 — Chassis ground:

Is the resistance 1 M

: or 

more?

Replace the accel-
erator pedal. <Ref. 
to SP(H4SO)-3, 
Accelerator 
Pedal.>

Repair the ground 
short circuit of har-
ness between 
ECM and accelera-
tor pedal position 
sensor connector. 
Replace the ECM if 
defective. <Ref. to 
FU(H6DO)-38, 
Engine Control 
Module (ECM).>

EN(H6DO)(diag)-335

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

EG:DTC P2123 THROTTLE/PEDAL POSITION SENSOR/SWITCH “D” CIRCUIT 

HIGH INPUT

DTC DETECTING CONDITION:
• Immediately at fault recognition
• GENERAL DESCRIPTION <Ref. to GD(H6DO)-201, DTC P2123 THROTTLE/PEDAL POSITION SEN-
SOR/SWITCH “D” 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(H6DO)(diag)-52,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(H6DO)(diag)-44, PROCEDURE,
Inspection Mode.>.
WIRING DIAGRAM:

E

C:

ECM

B136

B137

D:

B83

B315

*

*

4

6

5

1

3

2

B21

B23

B29

B22

B31

B30

A3

D2

B21

E2

D1

1 2 3 4
5 6 7 8

B122

B83

D3

A5

C6

B: B135

A: B134

D7

37

35

34

52

36

B122

B315

1 2 3 4 5 6

*

*

*

E

EN-06883

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

29 30 31

32 33

34 35

B135

B:

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

ACCELERATOR  

PEDAL 

POSITION

SENSOR

: TERMINAL No. OPTIONAL 
 ARRANGEMENT

EN(H6DO)(diag)-336

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. 23 — (B315) No. 6:
(B135) No. 29 — (B315) No. 5:

Is the resistance less than 1 

:? Go to step 2.

Repair the open 
circuit in harness 
between ECM and 
accelerator pedal 
position sensor 
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. 5 — Chassis 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 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. 6 (+) — 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. 21 — (B135) No. 23:

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.