Subaru Legacy III (2000-2003 year). Manual - part 494

EN(H4DOSTC)-146

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

5

CHECK HARNESS BETWEEN ECM AND IG-
NITION COIL & IGNITOR ASSEMBLY CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Disconnect the connector from ignition coil 

& ignitor assembly.

4) Measure the resistance of harness 

between ECM and ignition coil & ignitor 
assembly connector.

Connector & terminal

(B136) No. 21 — (E34) No. 1:
(B136) No. 22 — (E33) No. 1:
(B136) No. 23 — (E32) No. 1:
(B136) No. 24 — (E31) No. 1:

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

1 

Ω

Go to step 6.

Repair the har-
ness and connec-
tor.

NOTE:
In this case, repair
the following:
• Open circuit in 
harness between 
ECM and ignition 
coil & ignitor 
assembly connec-
tor
• Poor contact in 
coupling connector

6

CHECK HARNESS BETWEEN ECM AND IG-
NITION COIL & IGNITOR ASSEMBLY CON-
NECTOR.
Measure the resistance of harness between 
ECM and engine ground.

Connector & terminal:

(B136) No. 21 — Engine ground:
(B136) No. 22 — Engine ground:
(B136) No. 23 — Engine ground:
(B136) No. 24 — Engine ground:

Does the measured value exceed the specified 
value?

1 M

Ω

Go to step 7.

Repair the ground 
short circuit in har-
ness between 
ECM and ignition 
coil & ignitor 
assembly connec-
tor.

7

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 igni-
tion coil and ignitor 
assembly.

Step

Value

Yes

No

EN(H4DOSTC)-147

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

MEMO:

EN(H4DOSTC)-148

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

AE:DTC P0444 — EVAPORATIVE EMISSION CONTROL SYSTEM PURGE CON-

TROL VALVE CIRCUIT OPEN —

• TROUBLE SYMPTOM:

• Erroneous idling

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-00945

MAIN  RELAY

B47

1

2

3

5

4

6

BATTERY

E

E3

B47

B137

B137

E4

PURGE  CONTROL
SOLENOID  VALVE

ECM

16

2

1

SBF-5

3

4

1

2

5

6

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

2

1

1 2 3 4
5 6 7 8
9 10 11 12

13 14 15 16

B22

E4

1 2

B22

EN(H4DOSTC)-149

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

(B137) No. 16 (+) — 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 
SUBARU distribu-
tor service.

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

Go to step 2.

2

CHECK HARNESS BETWEEN PURGE CON-
TROL SOLENOID VALVE AND ECM CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from purge con-

trol solenoid valve and ECM.

3) Measure the resistance of harness 

between purge control solenoid valve con-
nector and engine ground.

Connector & terminal

(E4) No. 2 — Engine ground:

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

10 

Ω

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

Go to step 3.

3

CHECK HARNESS BETWEEN PURGE CON-
TROL SOLENOID VALVE AND ECM CON-
NECTOR.
Measure the resistance of harness between 
ECM and purge control solenoid valve of har-
ness connector.

Connector & terminal

(B137) No. 16 — (E4) No. 2:

Is the measured value less than the specified 
value?

1 

Ω

Go to step 4.

Repair the open 
circuit in harness 
between ECM and 
purge control sole-
noid valve connec-
tor.

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

4

CHECK PURGE CONTROL SOLENOID 
VALVE.
1) Remove the purge control solenoid valve.
2) Measure the resistance between purge 

control solenoid valve terminals.

Terminals

No. 1 — No. 2:

Is the measured value within the specified 
value?

10 — 100 

Ω

Go to step 5.

Replace the purge 
control solenoid 
valve.  <Ref. to 
EC(H4DOSTC)-6, 
Purge Control 
Solenoid Valve.>