Subaru Legacy III (2000-2003 year). Service manual — part 363

EN(H6DO)-254

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

BH:DTC P0506 — IDLE CONTROL SYSTEM RPM LOWER THAN EXPECTED —

• DTC DETECTING CONDITION:

• Two consecutive driving cycles with fault

• TROUBLE SYMPTOM:

• Engine is difficult to start.
• Engine does not start.
• Erroneous idling
• Engine stalls.

CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H6DO)-54, OP-
ERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H6DO)-47, OPERATION, Inspec-
tion Mode.>.
• WIRING DIAGRAM:

EN-01094

C17

C10

A22

B20

E1

ECM

2

3

1

9

3

IDLE

AIR CONTROL

SOLENOID

VALVE

E7

B20

E1

B47

B134

A:

B136

C:

B47

3

4

1

2

5

6

B134

B20

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

13 14 15 16

E7

B136

SBF-5

BATTERY

MAIN RELAY

1

2

3

5

4

6

4

F46

3 4

1 2

1 2 3

1 2

7

8 9

5

6

3

4

10 11 12
19 20 21

13 14 15 16

17 18

22 23 24

1 2 3 4

10 11 12

19 20 21

13

5

6

14 15

7

8 9

16 17

18

22

2

B108

F46

RHD

LHD

LHD

RHD

EN(H6DO)-255

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

Step

Value

Yes

No

1

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

Another DTC is displayed.

Inspect the rele-
vant DTC using
“List of Diagnostic
Trouble Code
(DTC)”. <Ref. to
EN(H6DO)-89, List
of Diagnostic
Trouble Code
(DTC).>

NOTE:
In this case, it is
not necessary to
inspect DTC
P0506.

Go to step 2.

2

CHECK AIR BY-PASS LINE.
1) Turn ignition switch to OFF.
2) Remove idle air control solenoid valve from

throttle body. <Ref. to FU(H6DO)-36, Idle
Air Control Solenoid Valve.>

3) Remove throttle body from intake manifold.

<Ref. to FU(H6DO)-16, Throttle Body.>

4) Using an air gun, force air into idle air con-

trol solenoid valve installation area. Confirm
that forced air subsequently escapes from
throttle body interior.
Does air flow out?

Air flows out.

Replace idle air
control solenoid
valve. <Ref. to
FU(H6DO)-36, Idle
Air Control Sole-
noid Valve.>

Replace throttle
body. <Ref. to
FU(H6DO)-16,
Throttle Body.>

EN(H6DO)-256

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

BI: DTC P0507 — IDLE CONTROL SYSTEM RPM HIGHER THAN EXPECTED —

• DTC DETECTING CONDITION:

• Two consecutive driving cycles with fault

• TROUBLE SYMPTOM:

• Engine does not return to normal idle speed.

CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H6DO)-54, OP-
ERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H6DO)-47, OPERATION, Inspec-
tion Mode.>.
• WIRING DIAGRAM:

EN-01094

C17

C10

A22

B20

E1

ECM

2

3

1

9

3

IDLE

AIR CONTROL

SOLENOID

VALVE

E7

B20

E1

B47

B134

A:

B136

C:

B47

3

4

1

2

5

6

B134

B20

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

13 14 15 16

E7

B136

SBF-5

BATTERY

MAIN RELAY

1

2

3

5

4

6

4

F46

3 4

1 2

1 2 3

1 2

7

8 9

5

6

3

4

10 11 12
19 20 21

13 14 15 16

17 18

22 23 24

1 2 3 4

10 11 12

19 20 21

13

5

6

14 15

7

8 9

16 17

18

22

2

B108

F46

RHD

LHD

LHD

RHD

EN(H6DO)-257

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

Step

Value

Yes

No

1

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

Another DTC is displayed.

Inspect the rele-
vant DTC using
“List of Diagnostic
Trouble Code
(DTC)”. <Ref. to
EN(H6DO)-89, List
of Diagnostic
Trouble Code
(DTC).>

NOTE:
In this case, it is
not necessary to
inspect DTC
P0507.

Go to step 2.

2

CHECK AIR INTAKE SYSTEM.
1) Turn ignition switch to ON.
2) Start engine, and idle it.
3) Check the following items.
•Loose installation of intake manifold, idle air
control solenoid valve and throttle body
•Cracks of intake manifold gasket, idle air con-
trol solenoid valve gasket and throttle body
gasket
•Disconnections of vacuum hoses

Is there a fault in air intake system?

There is a fault.

Repair air suction
and leaks.

Go to step 3.

3

CHECK THROTTLE CABLE.
Does throttle cable have play for adjustment?

Throttle cable has a play.

Go to step 4.

Adjust throttle
cable. <Ref. to
SP(H6DO)-8,
Accelerator Con-
trol Cable.>

4

CHECK AIR BY-PASS LINE.
1) Turn ignition switch to OFF.
2) Remove idle air control solenoid valve from

throttle body. <Ref. to FU(H6DO)-36, Idle
Air Control Solenoid Valve.>

3) Confirm that there are no foreign particles

in by-pass air line.
Are foreign particles in by-pass air line?

Foreign particles are in by-
pass air line.

Remove foreign
particles from by-
pass air line.

Replace idle air
control solenoid
valve. <Ref. to
FU(H6DO)-36, Idle
Air Control Sole-
noid Valve.>