Subaru Legacy IV (2008 year). Manual - part 361

EN(H4DOTC)(diag)-265

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

WIRING DIAGRAM:

EN-05678

B47

1

2

4

6

3

5

SBF-7

E

F9

13

12

11

14

1

2

2

1

3

4

16

15

5

6

B143

F37

B144

B21

E2

E41

E40

B134

A:

B136

C:

F37

F11

B21

E40

B47

B144

F9

B143

F37

E41

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

MAIN
SBF

10A

60A

9

10

8

7

E

E

11

5

20

8

C30
C19

C8

A19
A27
A29

6

1

28

47

3

2

1

6

4

1

2

9
2

16
18

14
12
10

4

14

4

F11

1 2

3

4

1

2

5

6

1

3

4 5 6

2

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

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

1
5

7

6

2

8

3

4
9

1 2 3 4

5 6 7 8 9

10 11 12 13 14

15 16 17 18 19 20

1 2 3 4

5 6 7 8 9

10 11 12 13 14 15 16 17 18 19 20

5

6

3

1
2

9

10

12

11

13

14

4

7 8

15

16

46

MAIN RELAY

BATTERY

RELAY HOLDER

SECONDARY 
AIR
COMBINATION 
VALVE RELAY1

SECONDARY 
AIR
COMBINATION 
VALVE RELAY2

SECONDARY 
AIR PUMP
RELAY

SECONDARY 
AIR PUMP

MAIN FUSE 
BOX (M/B)

ECM

SECONDARY AIR 

COMBINATION VALVE  RH

(WITH BUILT-IN PRESSURE SENSOR)

SECONDARY AIR 

COMBINATION 

VALVE LH

EN(H4DOTC)(diag)-266

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

Step

Check

Yes

No

1

CHECK HARNESS BETWEEN ECM AND 
SECONDARY AIR PUMP RELAY.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the ECM 
and secondary air pump relay.
3) Measure the voltage between ECM and 
chassis ground.

Connector & terminal

(B136) No. 8 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Repair short cir-
cuit of the harness 
to power supply 
between the ECM 
and secondary air 
pump relay.

Even if DTC is 
detected, the cir-
cuit has returned to 
a normal condition 
at this time. Repro-
duce the failure, 
and then perform 
the diagnosis 
again.

NOTE:
In this case, tem-
porary poor con-
tact of connector
may be the cause.

EN(H4DOTC)(diag)-267

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

CT:DTC P1420 FUEL TANK PRESSURE CONTROL SOL. VALVE CIRCUIT HIGH

DTC DETECTING CONDITION:
• Two consecutive driving cycles with fault
• GENERAL DESCRIPTION <Ref. to GD(H4DOTC)-177, DTC P1420 FUEL TANK PRESSURE CONTROL
SOL. VALVE CIRCUIT HIGH, Diagnostic Trouble Code (DTC) Detecting Criteria.>

CAUTION:
After repair or replacement of faulty parts, perform Clear Memory Mode <Ref. to EN(H4DOTC)(diag)-
52, OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(H4DOTC)(diag)-43, PRO-
CEDURE, Inspection Mode.>.
WIRING DIAGRAM:

EN-05679

SBF-7

E4

B47

E

5
3

6
4

2
1

2

1

C17

C28

D29

C7

R15

R213

R68

R144

R1

B97

14

15

2

2

1

1

7

1

5

E52

2

1

E52

R144

E4

B47

R67

B97

R213

R68

1 2

3

4

1

2

5

6

B21

1 2

1 2

3

4 5 6 7 8

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

1

2

3 4 5 6

1 2 3 4

5 6 7 8 9

10 11 12 13 14 15 16 17 18 19 20

R46

R67

6

B21

E2

11

48

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:

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

D:

B136

C:

B137

D:

44

MAIN RELAY

ECM

BATTERY

DRAIN VALVE

PRESSURE 

CONTROL 

SOLENOID VALVE

PURGE CONTROL 

SOLENOID VALVE  1

PURGE CONTROL 

SOLENOID VALVE  2

EN(H4DOTC)(diag)-268

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

Step

Check

Yes

No

1

CHECK HARNESS BETWEEN ECM AND 
PRESSURE CONTROL SOLENOID VALVE.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the ECM 
and pressure control solenoid valve.
3) Turn the ignition switch to ON.
4) Measure the voltage between ECM and 
chassis ground.

Connector & terminal

(B136) No. 28 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Repair the short 
circuit to power 
supply in the har-
ness between the 
ECM and pressure 
control solenoid 
valve connector.

Go to step 2.

2

CHECK PRESSURE CONTROL SOLENOID 
VALVE.
1) Turn the ignition switch to OFF.
2) Measure the resistance between pressure 
control solenoid valve terminals.

Terminals

No. 1 — No. 2:

Is the resistance less than 1 

:? Replace the pres-

sure control sole-
noid valve. <Ref. to 
EC(H4DOTC)-16, 
Pressure Control 
Solenoid Valve.>

Repair the poor 
contact of ECM 
connector.