Subaru Legacy III (2000-2003 year). Manual — part 508

EN(H4DOSTC)-202

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

AY:DTC P1236 — INTAKE CONTROL SOLENOID VALVE CIRCUIT HIGH —

• TROUBLE SYMPTOM:

• Poor driving performance

CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4DOSTC)-35,
OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4DOSTC)-33, Inspection
Mode.> .
• WIRING DIAGRAM:

EN-00939

B220

B47

E

BATTERY

MAIN RELAY

3

B136

ECM

SBF-5

5

2
1

4

6

B47

3

4

1

2

5

6

B220

SOLENOID
BOX ASSY

1

2

3

4

5

6

7

8

9

10

11

12

(A)

(B)

(C)

(D)

(E)

(F)

(A): RELIEF VALVE SOLENOID 2
(B): RELIEF VALVE SOLENOID 1
(C): EXHAUST VALVE CONTROL SOLENOID VALVE
(NEGATIVE PRESSURE)
(D): EXHAUST VALVE CONTROL SOLENOID VALVE
(POSITIVE PRESSURE)
(E): INTAKE AIR CONTROL SOLENOID VALVE
(F): EXHAUST VALVE CONTROL DUTY SOLENOID VALVE

C:

B137

D:

C11

C12

C3

C1

D22

D11

1 2 3 4
5 6 7 8
9 10 11 12

B136

1 2

7

8 9

5

6

3

4

10 11 12
19 20 21

13 14 15 16

17 18

22 23 24

B137

1

2

7

8

9

5

6

3

4

10 11 12

19 20 21
29 30 31

13 14 15 16 17

27 28

18

22 23 24 25 26

EN(H4DOSTC)-203

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

Step

Value

Yes

No

1

CHECK INPUT SIGNAL TO ECM.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM and

chassis ground.

Connector & terminal

(B137) No. 22 (+) — Chassis ground (

−−−−

):

Does the measured value exceed the spec-
ified value?

10 V

Go to step 3.

Go to step 2.

2

CHECK POOR CONTACT.
Check poor contact in ECM connector.
Is there poor contact in ECM connector?

There is poor contact.

Repair the poor
contact in ECM
connector.

Replace the ECM.
<Ref. to
FU(H4DOSTC)-
40, Engine Con-
trol Module.>

3

CHECK HARNESS BETWEEN INTAKE AIR
VALVE CONTROL SOLENOID VALVE AND
ECM CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from intake air

valve control solenoid valve.

3) Turn the ignition switch to ON.
4) Measure the voltage between ECM and

chassis ground.

Connector & terminal

(B137) No. 12 (+) — Chassis ground (

−−−−

):

Does the measured value exceed the spec-
ified value?

10 V

Repair the battery
short circuit in har-
ness between
ECM and intake
air valve control
solenoid valve
connector. After
repair, replace the
ECM. <Ref. to
FU(H4DOSTC)-
40, Engine Con-
trol Module.>

Go to step 4.

4

CHECK INTAKE AIR VALVE CONTROL SO-
LENOID VALVE.
1) Turn the ignition switch to OFF.
2) Measure the resistance between intake air

valve control solenoid valve terminals.

Terminals

No. 9 — No. 10:

Is the measured value less than the speci-
fied value?

1

Ω

Replace the intake
air valve control
solenoid valve
<Ref. to
IN(H4DOSTC)-19,
Solenoid Box
Assembly.> and
ECM. <Ref. to
FU(H4DOSTC)-
40, Engine Con-
trol Module.>

Go to step 5.

5

CHECK POOR CONTACT.
Check poor contact in ECM and intake air
valve control solenoid valve connectors.
Is there poor contact in ECM and intake air
valve control solenoid valve connectors?

There is poor contact.

Repair the poor
contact in ECM
and intake air
valve control sole-
noid valve connec-
tors.

Replace the ECM.
<Ref. to
FU(H4DOSTC)-
40, Engine Con-
trol Module.>

EN(H4DOSTC)-204

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

AZ:DTC P1237 — EXHAUST CONTROL VALVE SOLENOID CIRCUIT LOW (POS-

ITIVE PRESSURE) —

• TROUBLE SYMPTOM:

• Poor driving performance

CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4DOSTC)-35,
OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4DOSTC)-33, Inspection
Mode.> .
• WIRING DIAGRAM:

EN-00939

B220

B47

E

BATTERY

MAIN RELAY

3

B136

ECM

SBF-5

5

2
1

4

6

B47

3

4

1

2

5

6

B220

SOLENOID
BOX ASSY

1

2

3

4

5

6

7

8

9

10

11

12

(A)

(B)

(C)

(D)

(E)

(F)

(A): RELIEF VALVE SOLENOID 2
(B): RELIEF VALVE SOLENOID 1
(C): EXHAUST VALVE CONTROL SOLENOID VALVE
(NEGATIVE PRESSURE)
(D): EXHAUST VALVE CONTROL SOLENOID VALVE
(POSITIVE PRESSURE)
(E): INTAKE AIR CONTROL SOLENOID VALVE
(F): EXHAUST VALVE CONTROL DUTY SOLENOID VALVE

C:

B137

D:

C11

C12

C3

C1

D22

D11

1 2 3 4
5 6 7 8
9 10 11 12

B136

1 2

7

8 9

5

6

3

4

10 11 12
19 20 21

13 14 15 16

17 18

22 23 24

B137

1

2

7

8

9

5

6

3

4

10 11 12

19 20 21
29 30 31

13 14 15 16 17

27 28

18

22 23 24 25 26

EN(H4DOSTC)-205

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

Step

Value

Yes

No

1

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

chassis ground.

Connector & terminal

(B136) No. 1 (+) — Chassis ground (

−−−−

):

Does the measured value exceed the spec-
ified value?

10 V

Even if MI lights
up, the circuit has
returned to a nor-
mal condition at
this time. Contact
with your Subaru
distributor.

NOTE:
Inspection by DTM
is required, be-
cause probable
cause is deteriora-
tion of multiple
parts.

Go to step 2.

2

CHECK HARNESS BETWEEN EXHAUST
VALVE CONTROL SOLENOID VALVE (POS-
ITIVE PRESSURE) AND ECM CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from exhaust

valve control solenoid valve (positive pres-
sure) and ECM.

3) Measure the resistance of harness

between exhaust valve control solenoid
valve (positive pressure) connector and
engine ground.

Connector & terminal

(B220) No. 8 — Engine ground:

Does the measured value exceed the spec-
ified value?

1 M

Ω

Repair the ground
short circuit in har-
ness between
ECM and exhaust
valve control sole-
noid valve (posi-
tive pressure)
connector.

Go to step 3.

3

CHECK HARNESS BETWEEN EXHAUST
VALVE CONTROL SOLENOID VALVE (POS-
ITIVE PRESSURE) AND ECM CONNECTOR.
Measure the resistance of harness between
ECM and exhaust valve control solenoid valve
(positive pressure) of harness connector.

Connector & terminal

(B136) No. 1 — (B220) No. 8:

Does the measured value exceed the specified
value?

1 M

Ω

Go to step 4.

Repair the open
circuit in harness
between ECM and
exhaust valve con-
trol solenoid valve
(positive pres-
sure) connector.

4

CHECK EXHAUST VALVE CONTROL SOLE-
NOID VALVE (POSITIVE PRESSURE).
Measure the resistance between exhaust
valve control solenoid valve (positive pressure)
terminals.

Terminals

No. 7 — No. 8:

Is the measured value within the specified
value?

37 — 44

Ω

Go to step 5.

Replace the
exhaust valve con-
trol solenoid valve
(positive pres-
sure). <Ref. to
IN(H4DOSTC)-19,
Solenoid Box
Assembly.>

5

CHECK POWER SUPPLY TO EXHAUST
VALVE CONTROL SOLENOID VALVE (POS-
ITIVE PRESSURE).
1) Turn the ignition switch to ON.
2) Measure the voltage between exhaust

valve control solenoid valve (positive pres-
sure) and engine ground.

Connector & terminal

(B220) No. 7 (+) — Engine ground (

−−−−

):

Does the measured value exceed the spec-
ified value?

10 V

Go to step 6.

Repair open circuit
in harness
between main
relay and exhaust
valve control sole-
noid valve (posi-
tive pressure)
connector.