Subaru Legacy IV (2008 year). Manual - part 380

EN(H4DOTC)(diag)-341

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

Step

Check

Yes

No

1

CHECK OUTPUT SIGNAL OF ECM.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM and 
chassis ground.

Connector & terminal

(B136) No. 7 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Repair the poor 
contact of ECM 
connector.

Go to step 2.

2

CHECK HARNESS BETWEEN ECM AND 
PURGE CONTROL SOLENOID VALVE 2.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and 
purge control solenoid valve 2.
3) Measure the resistance between the purge 
control solenoid valve 2 connector and engine 
ground.

Connector & terminal

(E52) No. 2 — Engine ground:

Is the resistance 1 M

: or 

more?

Go to step 3.

Repair the ground 
short circuit of har-
ness between 
ECM and purge 
control solenoid 
valve 2 connector.

3

CHECK HARNESS BETWEEN ECM AND 
PURGE CONTROL SOLENOID VALVE 2.
Measure the resistance of harness between 
ECM and purge control solenoid valve 2.

Connector & terminal

(B136) No. 7 — (E52) No. 2:

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 of
harness between
ECM and purge
control solenoid
valve 2 connector
• Poor contact of
coupling connector

4

CHECK PURGE CONTROL SOLENOID 
VALVE 2.
1) Remove the purge control solenoid valve 2.
2) Measure the resistance between purge con-
trol solenoid valve 2 terminals.

Terminals

No. 1 — No. 2:

Is the resistance between 10 — 
100 

:?

Go to step 5.

Replace the purge 
control solenoid 
valve 2. <Ref. to 
EC(H4DOTC)-9, 
Purge Control 
Solenoid Valve.>

5

CHECK POWER SUPPLY TO PURGE CON-
TROL SOLENOID VALVE 2.
1) Turn the ignition switch to ON.
2) Measure the voltage between purge control 
solenoid valve 2 and engine ground.

Connector & terminal

(E52) No. 1 (+) — Engine ground (–):

Is the voltage 10 V or more?

Repair the poor 
contact in the 
purge control sole-
noid valve 2 con-
nector.

Repair the harness 
and connector.

NOTE:
In this case, repair
the following item:
• Open circuit of
harness between
the main relay and
purge control sole-
noid valve 2
• Poor contact of
coupling connector
• Poor contact of
main relay connec-
tor

EN(H4DOTC)(diag)-342

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

EB:DTC P2420 EVAPORATIVE EMISSION SYSTEM SWITCHING VALVE CONTROL 

CIRCUIT HIGH

DTC DETECTING CONDITION:
• Two consecutive driving cycles with fault
• GENERAL DESCRIPTION <Ref. to GD(H4DOTC)-227, DTC P2420 EVAPORATIVE EMISSION SYS-
TEM SWITCHING VALVE CONTROL CIRCUIT HIGH, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling

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)-343

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

Step

Check

Yes

No

1

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

Connector & terminal

(B136) No. 7 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Repair the short to 
power in the har-
ness between 
ECM and purge 
control solenoid 
valve 2 connector.

Go to step 2.

2

CHECK PURGE CONTROL SOLENOID 
VALVE 2.
1) Turn the ignition switch to OFF.
2) Measure the resistance between purge con-
trol solenoid valve 2 terminals.

Terminals

No. 1 — No. 2:

Is the resistance less than 1 

:? Replace the purge 

control solenoid 
valve 2. <Ref. to 
EC(H4DOTC)-9, 
Purge Control 
Solenoid Valve.>

Repair the poor 
contact of ECM 
connector.

EN(H4DOTC)(diag)-344

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

EC:DTC P2431 SECONDARY AIR INJECTION SYSTEM AIR FLOW /PRESSURE 

SENSOR CIRCUIT RANGE/PERFORMANCE

DTC DETECTING CONDITION:
• Two consecutive driving cycles with fault
• GENERAL DESCRIPTION <Ref. to GD(H4DOTC)-228, DTC P2431 SECONDARY AIR INJECTION SYS-
TEM AIR FLOW /PRESSURE SENSOR CIRCUIT RANGE/PERFORMANCE, 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.>.