Subaru Legacy III (2000-2003 year). Manual - part 214

EN(H4SOw/oOBD)-46

ENGINE (DIAGNOSTICS)

DIAGNOSTICS FOR ENGINE STARTING FAILURE

D: IGNITION CONTROL SYSTEM

CAUTION:
After repair or replacement of faulty parts, conduct CLEAR MEMORY and INSPECTION MODES. <Ref. 
to EN(H4SOw/oOBD)-28, OPERATION, Clear Memory Mode.>  and <Ref. to EN(H4SOw/oOBD)-26, OP-
ERATION, Inspection Mode.>
• WIRING DIAGRAM:

EN-01047

26

25

B134

B72

3 4

1 2

3 4

1 2

E12

B22

1 2 3 4
5 6 7 8

13 14 15 16

9 10 11 12

6

5

4

3

4

1

2

IGNITOR

&

IGNITION COIL ASSY

B22

E3

E12

SBF-1

SBF-4

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

ECM

BATTERY

NO. 11

4

1

B72

IGNITION 
SWITCH

3

4

1

2

EN(H4SOw/oOBD)-47

ENGINE (DIAGNOSTICS)

DIAGNOSTICS FOR ENGINE STARTING FAILURE

Step

Value

Yes

No

1

CHECK IGNITION SYSTEM FOR SPARKS.
1) Remove plug cord cap from each spark 

plug.

2) Install new spark plug on plug cord cap.

CAUTION:

Do not remove spark plug from engine.

3) Contact spark plug's thread portion on 

engine.

4) Crank engine to check that spark occurs at 

each cylinder.
Does spark occur at each cylinder?

Spark occurs.

Check fuel pump 
system. <Ref. to 
EN(H4SOw/
oOBD)-50, FUEL 
PUMP CIRCUIT, 
Diagnostics for 
Engine Starting 
Failure.>

Go to step 2.

2

CHECK POWER SUPPLY CIRCUIT FOR IG-
NITION COIL & IGNITOR ASSEMBLY.
1) Turn ignition switch to OFF.
2) Disconnect connector from ignition coil & 

ignitor assembly.

3) Turn ignition switch to ON.
4) Measure power supply voltage between 

ignition coil & ignitor assembly connector 
and engine ground.

Connector & terminal

(E12) No. 2 (+) — Engine ground (

−−−−

):

Does the measured value exceed the spec-
ified value?

10 V

Go to step 3.

Repair harness 
and connector.

NOTE:
In this case, repair
the following:
• Open circuit or 
ground short in 
harness between 
ignition coil & igni-
tor assembly, and 
ignition switch 
connector
• Poor contact in 
coupling connector 
(B22)

3

CHECK HARNESS OF IGNITION COIL & IG-
NITOR ASSEMBLY GROUND CIRCUIT.
1) Turn ignition switch to OFF.
2) Measure resistance between ignition coil & 

ignitor assembly connector and engine 
ground.

Connector & terminal

(E12) No. 3 — Engine ground:

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

5 

Ω

Go to step 4.

Repair harness 
and connector.

NOTE:
In this case, repair
the following:
• Open circuit in 
harness between 
ignition coil & igni-
tor assembly con-
nector and engine 
grounding terminal

4

CHECK IGNITION COIL & IGNITOR ASSEM-
BLY.
1) Remove spark plug cords.
2) Measure resistance between spark plug 

cord contact portions to check secondary 
coil.

Terminals

No. 1 — No. 2:

Is the measured value within the specified 
value?

10 — 15 

Ω

Go to step 5.

Replace ignition 
coil & ignitor 
assembly.

5

CHECK IGNITION COIL & IGNITOR ASSEM-
BLY.
Measure resistance between spark plug cord 
contact portions to check secondary coil.

Terminals

No. 3 — No. 4:

Is the measured value within the specified 
value?

10 — 15 

Ω

Go to step 6.

Replace ignition 
coil & ignitor 
assembly.

EN(H4SOw/oOBD)-48

ENGINE (DIAGNOSTICS)

DIAGNOSTICS FOR ENGINE STARTING FAILURE

6

CHECK INPUT SIGNAL FOR IGNITION COIL 
& IGNITOR ASSEMBLY.
Check if voltage varies synchronously with 
engine speed when cranking, while monitoring 
voltage between ignition coil & ignitor assem-
bly connector and engine ground.

Connector & terminal

(E12) No. 1 (+) — Engine ground (–):

Does the measured value exceed the specified 
value?

10 V

Go to step 7.

Replace ignition 
coil & ignitor 
assembly.

7

CHECK INPUT SIGNAL FOR IGNITION COIL 
& IGNITOR ASSEMBLY.
Check if voltage varies synchronously with 
engine speed when cranking, while monitoring 
voltage between ignition coil & ignitor assem-
bly connector and engine ground.

Connector & terminal

(E12) No. 4 (+) — Engine ground (–):

Does the measured value exceed the specified 
value?

10 V

Go to step 8.

Replace ignition 
coil & ignitor 
assembly.

8

CHECK HARNESS BETWEEN ECM AND IG-
NITION COIL & IGNITOR ASSEMBLY CON-
NECTOR.
1) Disconnect connector from ECM.
2) Measure resistance of harness between 

ECM and ignition coil & ignitor assembly 
connector.

Connector & terminal

(B134) No. 26 — (E12) No. 4:

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

1 

Ω

Go to step 9.

Repair harness 
and connector.

NOTE:
In this case, repair
the following:
• Open circuit in 
harness between 
ECM and ignition 
coil & ignitor 
assembly connec-
tor
• Poor contact in 
a coupling connec-
tor (B22)

9

CHECK HARNESS BETWEEN ECM AND IG-
NITION COIL & IGNITOR ASSEMBLY CON-
NECTOR.
Measure resistance of harness between ECM 
and ignition coil & ignitor assembly connector.

Connector & terminal

(B134) No. 25 — (E12) No. 1:

Is the measured value less than the specified 
value?

1 

Ω

Go to step 10.

Repair harness 
and connector.

NOTE:
In this case, repair
the following:
• Open circuit in 
harness between 
ECM and ignition 
coil & ignitor 
assembly connec-
tor
• Poor contact in 
a coupling connec-
tor (B22)

10

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

Connector & terminal:

(B134) No. 26 — Chassis ground:

Does the measured value exceed the specified 
value?

1 M

Ω

Go to step 11.

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

Step

Value

Yes

No

EN(H4SOw/oOBD)-49

ENGINE (DIAGNOSTICS)

DIAGNOSTICS FOR ENGINE STARTING FAILURE

11

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

Connector & terminal

(B134) No. 25 — Chassis ground:

Does the measured value exceed the specified 
value?

1 M

Ω

Go to step 12.

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

12

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

There is poor contact.

Repair poor con-
tact in ECM con-
nector.

Check spark plug 
and spark plug 
cord.  <Ref. to 
IG(H4SOw/
oOBD)-5, Spark 
Plug.> <Ref. to 
IG(H4SOw/
oOBD)-10, Spark 
Plug Cord.>

Step

Value

Yes

No