Subaru Legacy (2005 year). Manual - part 487

EN(H6DO)(diag)-261

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

8

CHECK SENSOR OUTPUT.
1) Connect all the connectors.
2) Turn the ignition switch to ON.
3) Read the data of main throttle sensor signal 
using Subaru Select Monitor.

NOTE:

For detailed operation procedure, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(H6DO)(diag)-26, Subaru Select Moni-
tor.>

Is the voltage less than 4.63 
V?

Go to step 9.

Go to step 11.

9

CHECK SENSOR OUTPUT.
Read the data of sub throttle sensor signal 
using Subaru Select Monitor.

NOTE:

For detailed operation procedure, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(H6DO)(diag)-26, Subaru Select Moni-
tor.>

Is the voltage less than 4.73 
V?

Go to step 10.

Go to step 11.

10

CHECK POOR CONTACT.
Check poor contact in connector between 
ECM and electronic throttle control.

Is there poor contact?

Repair the poor 
contact.

Temporary poor 
contact occurred, 
but it is normal at 
present.

11

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

Connector & terminal

(B136) No. 35 — (E57) No. 3:
(B136) No. 18 — (E57) No. 6:
(B136) No. 29 — (E57) No. 4:

Is the resistance less than 1 
Ω?

Go to step 12.

Repair the open 
circuit of harness 
connector.

12

CHECK HARNESS BETWEEN ECM AND 
ELECTRONIC THROTTLE CONTROL.
1) Connect the ECM connector.
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 
Ω?

Go to step 13.

Repair the poor 
contact in ECM 
connector. 
Replace the ECM 
if defective. <Ref. 
to FU(H6DO)-34, 
Engine Control 
Module (ECM).>

13

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

Connector & terminal

(E57) No. 5 (+) — Engine ground (

−

):

Is the voltage less than 10 V?

Go to step 14.

Repair the battery 
short circuit of har-
ness between 
ECM connector 
and electronic 
throttle control 
connector.

14

CHECK HARNESS BETWEEN ECM AND 
ELECTRONIC THROTTLE CONTROL.
Measure the voltage between electronic throt-
tle control connector and engine ground.

Connector & terminal

(E57) No. 6 (+) — Engine ground (

−

):

(E57) No. 4 (+) — Engine ground (

−

):

Is the voltage less than 10 V?

Go to step 15.

Repair the short 
circuit of harness 
between ECM 
connector and 
electronic throttle 
control connector.

Step

Check

Yes

No

EN(H6DO)(diag)-262

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

15

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

Connector & terminal

(B136) No. 18 — (B136) No. 16:
(B136) No. 29 — (B136) No. 16:

Is the resistance more than 1 
M

Ω?

Go to step 16.

Repair the short 
circuit to sensor 
power supply.

16

CHECK ELECTRONIC THROTTLE CON-
TROL HARNESS.
1) Disconnect the connector from ECM.
2) Disconnect the connectors from electronic 
throttle control.
3) Measure the resistance between electronic 
throttle control connector terminals.

Connector & terminal

(E57) No. 6 — (E57) No. 4:

Is the resistance more than 1 
M

Ω?

Repair the poor 
contact in ECM 
connector. 
Replace the ECM 
if defective. <Ref. 
to FU(H6DO)-34, 
Engine Control 
Module (ECM).>

Repair the short 
circuit of harness.

Step

Check

Yes

No

EN(H6DO)(diag)-263

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

DD:DTC P2138 THROTTLE/PEDAL POSITION SENSOR/SWITCH “D” / “E” 

VOLTAGE CORRELATION

DTC DETECTING CONDITION:
Immediately at fault recognition
TROUBLE SYMPTOM:
• Erroneous idling
• Poor driving performance
WIRING DIAGRAM:

EN-03506

B315

E

C:

ECM

B136

B137

D:

B83

B315

ACCELERATOR

PEDAL POSITION

SENSOR

*

*

3

5

4

1

2

6

C15

C17

C34

C16

C28

C35

D1

D2

B21

E2

B1

B138

1 2 3 4
5 6 7 8

MAIN

SUB

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:

C:

D:

B122

B83

B122

D3

B: B135

B4

37

36

35

1 2 3 4 5 6

*

*

1
1

1

*

2

*

2

1

 : TERMINAL No. 
   RANDOM ARRANGEMENT

*

1

LHD

RHD

RHD

*

: TERMINAL No. 
  RANDOM ARRANGEMENT 
  AMONG 3,4,7, AND 8

2

B122

B138

: LHD

: RHD

EN(H6DO)(diag)-264

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

Step

Check

Yes

No

1

CHECK ACCELERATOR PEDAL POSITION 
SENSOR OUTPUT.
1) Turn the ignition switch to ON.
2) Read the data of main accelerator pedal 
position sensor signal and sub accelerator 
pedal position sensor signal using Subaru 
Select Monitor.

NOTE:

For detailed operation procedure, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(H6DO)(diag)-26, Subaru Select Moni-
tor.>

Is the voltage more than 0.4 V? Go to step 2.

Go to step 3.

2

CHECK POOR CONTACT.
Check poor contact in connector between 
ECM and accelerator pedal position sensor.

Is there poor contact?

Repair the poor 
contact.

Go to step 12.

3

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

Connector & terminal

(B136) No. 17 — (B315) No. 5:
(B136) No. 15 — (B315) No. 3:
(B136) No. 28 — (B315) No. 2:
(B136) No. 16 — (B315) No. 1:

Is the resistance less than 1 
Ω?

Go to step 4.

Repair the open 
circuit of harness 
connector.

4

CHECK HARNESS BETWEEN ECM AND AC-
CELERATOR PEDAL POSITION SENSOR.
Measure the resistance between ECM connec-
tor and chassis ground.

Connector & terminal

(B136) No. 17 — Chassis ground:
(B136) No. 15 — Chassis ground:
(B136) No. 28 — Chassis ground:
(B136) No. 16 — Chassis ground:

Is the resistance more than 1 
M

Ω?

Go to step 5.

Repair the ground 
short circuit of har-
ness.

5

CHECK POWER SUPPLY OF ACCELERA-
TOR PEDAL POSITION SENSOR.
1) Connect the ECM connector.
2) Turn the ignition switch to ON.
3) Measure the voltage between accelerator 
pedal position sensor connector and engine 
ground.

Connector & terminal

(B315) No. 3 (+) — Engine ground (

−

):

(B315) No. 1 (+) — Engine ground (

−

):

Is the voltage 4.5 — 5.5 V?

Go to step 6.

Repair the poor 
contact in ECM 
connector. 
Replace the ECM 
if defective. <Ref. 
to FU(H6DO)-34, 
Engine Control 
Module (ECM).>

6

CHECK ACCELERATOR PEDAL POSITION 
SENSOR.
Measure the resistance of accelerator pedal 
position sensor.

Terminal

No. 3 — No. 4:

Is the resistance 1.2 — 4.8 
k

Ω?

Go to step 7.

Replace the accel-
erator pedal posi-
tion sensor.

7

CHECK ACCELERATOR PEDAL POSITION 
SENSOR.
Measure the resistance of accelerator pedal 
position sensor.

Terminal

No. 1 — No. 6:

Is the resistance 0.75 — 3.15 
k

Ω?

Go to step 8.

Replace the accel-
erator pedal posi-
tion sensor.