Subaru Legacy III (2000-2003 year). Service manual — part 168

EN(H4SO)-284

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

CE:DTC P1510 — ISC SOLENOID VALVE SIGNAL #1 CIRCUIT MALFUNCTION

(LOW INPUT) —

NOTE:
For the diagnostic procedure, refer to DTC P1516. <Ref. to EN(H4SO)-286, DTC P1516 — ISC SOLENOID
VALVE SIGNAL #4 CIRCUIT MALFUNCTION (LOW INPUT) —, Diagnostic Procedure with Diagnostic Trou-
ble Code (DTC).>

CF:DTC P1511 — ISC SOLENOID VALVE SIGNAL #1 CIRCUIT MALFUNCTION

(HIGH INPUT) —

NOTE:
For the diagnostic procedure, refer to DTC P1517. <Ref. to EN(H4SO)-288, DTC P1517 — ISC SOLENOID
VALVE SIGNAL #4 CIRCUIT MALFUNCTION (HIGH INPUT) —, Diagnostic Procedure with Diagnostic
Trouble Code (DTC).>

CG:DTC P1512 — ISC SOLENOID VALVE SIGNAL #2 CIRCUIT MALFUNCTION

(LOW INPUT) —

NOTE:
For the diagnostic procedure, refer to DTC P1516. <Ref. to EN(H4SO)-286, DTC P1516 — ISC SOLENOID
VALVE SIGNAL #4 CIRCUIT MALFUNCTION (LOW INPUT) —, Diagnostic Procedure with Diagnostic Trou-
ble Code (DTC).>

CH:DTC P1513 — ISC SOLENOID VALVE SIGNAL #2 CIRCUIT MALFUNCTION

(HIGH INPUT) —

NOTE:
For the diagnostic procedure, refer to DTC P1517. <Ref. to EN(H4SO)-288, DTC P1517 — ISC SOLENOID
VALVE SIGNAL #4 CIRCUIT MALFUNCTION (HIGH INPUT) —, Diagnostic Procedure with Diagnostic
Trouble Code (DTC).>

CI: DTC P1514 — ISC SOLENOID VALVE SIGNAL #3 CIRCUIT MALFUNCTION

(LOW INPUT) —

NOTE:
For the diagnostic procedure, refer to DTC P1516. <Ref. to EN(H4SO)-286, DTC P1516 — ISC SOLENOID
VALVE SIGNAL #4 CIRCUIT MALFUNCTION (LOW INPUT) —, Diagnostic Procedure with Diagnostic Trou-
ble Code (DTC).>

CJ:DTC P1515 — ISC SOLENOID VALVE SIGNAL #3 CIRCUIT MALFUNCTION

(HIGH INPUT) —

NOTE:
For the diagnostic procedure, refer to DTC P1517. <Ref. to EN(H4SO)-288, DTC P1517 — ISC SOLENOID
VALVE SIGNAL #4 CIRCUIT MALFUNCTION (HIGH INPUT) —, Diagnostic Procedure with Diagnostic
Trouble Code (DTC).>

EN(H4SO)-285

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

MEMO:

EN(H4SO)-286

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

CK:DTC P1516 — ISC SOLENOID VALVE SIGNAL #4 CIRCUIT MALFUNCTION

(LOW INPUT) —

• DTC DETECTING CONDITION:

• Immediately at fault recognition

• TROUBLE SYMPTOM:

• Erroneous idling
• Engine stalls.
• Engine breathing

CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode<Ref. to EN(H4SO)-47, OPER-
ATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4SO)-40, OPERATION, Inspection
Mode.> .
• WIRING DIAGRAM:

EN-01134

F44

B61

6

RHD

RHD

20

6

5

19

B21

E2

ECM

2

5

6

3

4

1

3

4

1

2

IDLE

AIR CONTROL

SOLENOID

VALVE

E7

B22

E3

B47

B134

B47

3

4

1

2

5

6

B134

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

B22

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

13 14 15 16

E7

1

3

4 5 6

2

B21

1 2

3 4

5

6 7

8

9 10

11 12

13

14 15

16

17 18

19 20

SBF-5

BATTERY

MAIN RELAY

1

2

3

5

4

6

1

1 2 3 4
5 6 7 8

F44

LHD

LHD

EN(H4SO)-287

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

Step

Value

Yes

No

1

CHECK POWER SUPPLY TO IDLE AIR CON-
TROL SOLENOID VALVE.
1) Turn ignition switch to OFF.
2) Disconnect connector from idle air control

solenoid valve.

3) Turn ignition switch to ON.
4) Measure voltage between idle air control

solenoid valve connector and engine
ground.

Connector & terminal

(E7) No. 2 (+) — Engine ground (

−−−−

):

(E7) No. 5 (+) — Engine ground (

−−−−

):

Does the measured value exceed the spec-
ified value?

10 V

Go to step 2.

Repair harness
and connector.

NOTE:
In this case, repair
the following:
• Open circuit in
harness between
idle air control
solenoid valve and
main relay con-
nector
• Poor contact in
coupling connector

2

CHECK HARNESS BETWEEN ECM AND
IDLE AIR CONTROL SOLENOID VALVE
CONNECTOR.
1) Turn ignition switch to OFF.
2) Measure resistance between ECM and idle

air control solenoid valve connector.

Connector & terminal

DTC P1510; (B134) No. 20 — (E7) No. 4:
DTC P1512; (B134) No. 6 — (E7) No. 1:
DTC P1514; (B134) No. 5 — (E7) No. 6:
DTC P1516; (B134) No. 19 — (E7) No. 3:

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

1

Ω

Go to step 3.

Repair harness
and connector.

NOTE:
In this case, repair
the following:
• Open circuit in
harness between
ECM and idle air
control solenoid
valve connector
• Poor contact in
coupling connector

3

CHECK HARNESS BETWEEN ECM AND
IDLE AIR CONTROL SOLENOID VALVE
CONNECTOR.
1) Disconnect connector from ECM.
2) Measure resistance between ECM connec-

tor and chassis ground.

Connector & terminal

DTC P1510; (B134) No. 20 — Chassis
ground:
DTC P1512; (B134) No. 6 — Chassis
ground:
DTC P1514; (B134) No. 5 — Chassis
ground:
DTC P1516; (B134) No. 19 — Chassis
ground:

Does the measured value exceed the spec-
ified value?

1 M

Ω

Repair ground
short circuit in har-
ness between
ECM and idle air
control solenoid
valve connector.

Go to step 4.

4

CHECK POOR CONTACT.
Check poor contact in ECM connector and idle
air control solenoid valve connector.
Is there poor contact in ECM connector or idle
air control solenoid valve connector?

There is poor contact.

Repair poor con-
tact in ECM con-
nector or idle air
control solenoid
valve connector.

Replace idle air
control solenoid
valve. <Ref. to
FU(H4SO)-34, Idle
Air Control Sole-
noid Valve.>