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.