Subaru Impreza 3 / Impreza WRX / Impreza WRX STI. Manual — part 301

EN(H4DOTC)(diag)-428

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

Step

Check

Yes

No

1

CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed?

Check the appropri-
ate DTC using the
“List of Diagnostic
Trouble Code
(DTC)”. <Ref. to
EN(H4DOTC)(diag)
-87, List of Diagnos-
tic Trouble Code
(DTC).>

Go to step

2.

2

CHECK ELCM PUMP.
Operate the ELCM pump using the Subaru
Select Monitor.
NOTE:

Refer to “Compulsory Valve Operation Check
Mode” for more operation procedures. <Ref. to
EN(H4DOTC)(diag)-64, Compulsory Valve Op-
eration Check Mode.>

Does the ELCM pump operate? Go to step

6.

Go to step

3.

3

CHECK POWER SUPPLY OF LEAK CHECK
VALVE ASSEMBLY.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the leak
check valve assembly.
3) Turn the ignition switch to ON.
4) Measure the voltage between the leak
check valve assembly connector and chassis
ground.

Connector & terminal

(R400) No. 3 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Go to step

4.

Repair the harness
and connector.
NOTE:

In this case, repair
the following item:
• Open circuit in
harness between
the main relay and
the leak check
valve

assembly

connector
• Poor contact of
main relay connec-
tor
• Poor contact of
coupling connector

4

CHECK HARNESS BETWEEN ECM AND
LEAK CHECK VALVE ASSEMBLY CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness between
ECM connector and the leak check valve
assembly connector.

Connector & terminal

(B137) No. 27 — (R400) No. 4:

Is the resistance less than 1 Ω? Go to step

5.

Repair the harness
and connector.
NOTE:

In this case, repair
the following item:
• Open circuit in
harness between
ECM

connector

and the leak check
valve

assembly

connector
• Poor contact of
coupling connector

5

CHECK HARNESS BETWEEN ECM AND
LEAK CHECK VALVE ASSEMBLY CONNEC-
TOR.
1) Measure the resistance of harness between
ECM connector and chassis ground.

Connector & terminal

(B137) No. 27 — Chassis ground:

Is the resistance 1 MΩ or
more?

Replace the leak
check valve
assembly. <Ref. to
EC(STI)-19, Leak
Check Valve
Assembly.> <Ref.
to EC(w/o STI)-20,
Leak Check Valve
Assembly.>

Repair the short
circuit to ground in
harness between
ECM connector
and leak check
valve assembly
connector.

EN(H4DOTC)(diag)-429

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

6

CHECK ELCM SWITCHING VALVE.
Operate the ELCM switching valve using the
Subaru Select Monitor.
NOTE:

Refer to “Compulsory Valve Operation Check
Mode” for more operation procedures. <Ref. to
EN(H4DOTC)(diag)-64, Compulsory Valve Op-
eration Check Mode.>

Does the ELCM switching valve
operate?

Go to step

10.

Go to step

7.

7

CHECK POWER SUPPLY OF LEAK CHECK
VALVE ASSEMBLY.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the leak
check valve assembly.
3) Turn the ignition switch to ON.
4) Measure the voltage between the leak
check valve assembly connector and chassis
ground.

Connector & terminal

(R400) No. 5 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Go to step

8.

Repair the harness
and connector.
NOTE:

In this case, repair
the following item:
• Open circuit in
harness between
the main relay and
the leak check
valve

assembly

connector
• Poor contact of
main relay connec-
tor
• Poor contact of
coupling connector

8

CHECK HARNESS BETWEEN ECM AND
LEAK CHECK VALVE ASSEMBLY CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness between
ECM connector and the leak check valve
assembly connector.

Connector & terminal

(B135) No. 4 — (R400) No. 1:

Is the resistance less than 1 Ω? Go to step

9.

Repair the harness
and connector.
NOTE:

In this case, repair
the following item:
• Open circuit in
harness between
ECM

connector

and the leak check
valve

assembly

connector
• Poor contact of
coupling connector

9

CHECK HARNESS BETWEEN ECM AND
LEAK CHECK VALVE ASSEMBLY CONNEC-
TOR.
1) Measure the resistance of harness between
ECM connector and chassis ground.

Connector & terminal

(B135) No. 4 — Chassis ground:

Is the resistance 1 MΩ or
more?

Replace the leak
check valve
assembly. <Ref. to
EC(STI)-19, Leak
Check Valve
Assembly.> <Ref.
to EC(w/o STI)-20,
Leak Check Valve
Assembly.>

Repair the short
circuit to ground in
harness between
ECM connector
and leak check
valve assembly
connector.

Step

Check

Yes

No

EN(H4DOTC)(diag)-430

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

10

CHECK EVAPORATIVE EMISSION CON-
TROL SYSTEM.
Perform drive cycle I. <Ref. to
EN(H4DOTC)(diag)-59, DRIVE CYCLE H,
PROCEDURE, Drive Cycle.>

Is DTC P2404 displayed on the
display?

Replace the leak
check valve
assembly. <Ref. to
EC(STI)-19, Leak
Check Valve
Assembly.> <Ref.
to EC(w/o STI)-20,
Leak Check Valve
Assembly.>

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,
temporary open or
short circuit of har-
ness may be the
cause.

Step

Check

Yes

No

EN(H4DOTC)(diag)-431

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

FF:DTC P2419 EVAPORATIVE EMISSION SYSTEM SWITCHING VALVE CON-

TROL CIRCUIT LOW

DTC DETECTING CONDITION:

• Immediately at fault recognition

• GENERAL DESCRIPTION <Ref. to GD(H4DOTC)-280, DTC P2419 EVAPORATIVE EMISSION SYS-

TEM SWITCHING VALVE CONTROL CIRCUIT LOW, Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:

After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(H4DOTC)(diag)-63,

OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(H4DOTC)(diag)-49, PROCE-

DURE, Inspection Mode.>.

WIRING DIAGRAM:

• Engine electrical system, without SI-DRIVE <Ref. to WI-32, WITHOUT SI-DRIVE, WIRING DIAGRAM,

Engine Electrical System.>

• Engine electrical system, with SI-DRIVE <Ref. to WI-48, WITH SI-DRIVE, WIRING DIAGRAM, Engine

Electrical System.>

ECM

B97

R1

10

B92

2 3 4 5

6 7 8 9

11 12 13 14

17 18 19 20

1

10

15 16

B97

R82

1 2

3 4 5

6 7 8 9 10 11 12

B220

B83

4

1 2 3

6

5

*

B83

*

*

D27

B22

C21

B30

B4

B135

B:

B136

C:

B137

D:

14

17

15

16

13

8

R81

R82

1

5

8

7

6

4

3

R400

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

22 23

11 12 13 14 15

24 25

26

16 17

18 19 20 21

27

28 29

30 31

B137

D:

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:

1 2

4

5 6 7 8

3

R400

24

23

22

21

B220

13
14

15 16

17

27

24

25
26

20

21
22

23

29
30

31

28

32 35

33
34

37
38

39

36

40

8

9

10

11 12

1

2

5

3

4

7

6

19

18

B220

4

3

EN-09250

R5

B92

E

SBF-7

BATTERY

FUSE

(RELAY BLOCK)

MAIN RELAY

LEAK CHECK VALVE ASSY

VACUUM

PUMP

PRESSURE

SENSOR

SWITCHING

VALVE

: TERMINAL No. OPTIONAL ARRANGEMENT