Subaru Legacy (2005 year). Manual - part 436

EN(H6DO)(diag)-57

ENGINE (DIAGNOSTICS)

Diagnostics for Engine Starting Failure

C: CHECK POWER SUPPLY AND GROUND LINE OF ENGINE CONTROL MOD-

ULE (ECM)

CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H6DO)(diag)-41, 
OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H6DO)(diag)-34, PROCEDURE, 
Inspection Mode.>.
WIRING DIAGRAM:

EN-03490

BATTERY

IGNITION
SWITCH

MAIN RELAY

SBF-6

MAIN SBF

SBF-7

B72

B6

B5

D16

A6

D2

A7

B12

D3

D7

D1

B19

D14

No.12

B47

E2

B21

ECM

E

E

3

6

B134

B135

A:

D: B137

B:

B4

52

37

36

34

12

3

4

1

2

5

6

B47

No.13

B1

35

B134

5

6

7

8

2

1

9

4

3

10

24

22 23

25

11 12 13 14 15

26 27

28

16 17

18 19 20 21

33 34

29

32

30 31

B135

5

6

7

8

2

1

9

4

3

10

24

22 23

25

11 12 13 14 15

26 27

28

16 17 18 19

20 21

29 30 31

32 33

34 35

B137

5

6

7

8

2

1

9

4

3

10

22 23

11 12 13 14 15

24 25

26

16 17

18 19 20 21

27

28 29

30 31

B21

1 2 3 4

12 13 14 15

5 6 7 8

16 17 18 19

9 10 11

20 21 22

23 24 25 26 27 28 29 30 31 32 33

35

34

37

36

39

38

41

40

43

42

44

45

47

46

49

48

51

50

53

52

54

B72

1

3

4 5 6

2

A:

B:

D:

SBF-5

A4

A5

54

3
5

6
4

1
2

TO OXYGEN SENSOR

EN(H6DO)(diag)-58

ENGINE (DIAGNOSTICS)

Diagnostics for Engine Starting Failure

Step

Check

Yes

No

1

CHECK MAIN RELAY.
1) Turn the ignition switch to OFF.
2) Remove the main relay.
3) Connect the battery to main relay terminals 
No. 1 and No. 2.
4) Measure the resistance between main relay 
terminals.

Terminal

No. 3 — No. 5:
No. 4 — No. 6:

Is the resistance less than 10 
Ω?

Go to step 2.

Replace the main 
relay.

2

CHECK GROUND CIRCUIT FOR ECM.
1) Disconnect the connector from ECM.
2) Measure the resistance of harness 
between ECM and chassis ground.

Connector & terminal

(B134) No. 4 — Chassis ground:
(B134) No. 5 — Chassis ground:
(B134) No. 6 — Chassis ground:
(B134) No. 7 — Chassis ground:
(B135) No. 1 — Chassis ground:
(B135) No. 4 — Chassis ground:
(B135) No. 12 — Chassis ground:
(B137) No. 1 — Chassis ground:
(B137) No. 2 — Chassis ground:
(B137) No. 3 — Chassis ground:
(B137) No. 7 — Chassis ground:

Is the resistance less than 5 
Ω?

Go to step 3.

Repair the open 
circuit of harness 
between ECM 
connector and 
engine grounding 
terminal.

3

CHECK INPUT VOLTAGE OF ECM.
Measure the voltage between ECM connector 
and chassis ground.

Connector & terminal

(B135) No. 19 (+) — Chassis ground (

−

):

Is the voltage more than 10 V? Go to step 4.

Repair the open or 
ground short cir-
cuit of power sup-
ply circuit.

4

CHECK INPUT VOLTAGE OF ECM.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM con-
nector and chassis ground.

Connector & terminal

(B137) No. 14 (+) — Chassis ground (

−

):

Is the voltage more than 10 V? Go to step 5.

Repair the open or 
ground short cir-
cuit of power sup-
ply circuit.

5

CHECK INPUT VOLTAGE OF MAIN RELAY.
Measure the voltage between main relay con-
nector and chassis ground.

Connector & terminal

(B47) No. 1 (+) — Chassis ground (

−

):

Is the voltage more than 10 V? Go to step 6.

Repair the open 
circuit of harness 
between ECM 
connector and 
main relay connec-
tor.

6

CHECK INPUT VOLTAGE OF ECM.
1) Connect the connectors to ECM and main 
relay.
2) Turn the ignition switch to ON.
3) Measure the voltage between ECM con-
nector and chassis ground.

Connector & terminal

(B137) No. 16 (+) — Chassis ground (

−

):

Is the voltage more than 10 V? Go to step 7.

Repair the open or 
ground short cir-
cuit of harness 
between ECM 
connector and 
main relay connec-
tor.

7

CHECK INPUT VOLTAGE OF MAIN RELAY.
Measure the voltage between main relay con-
nector and chassis ground.

Connector & terminal

(B47) No. 5 (+) — Chassis ground (

−

):

(B47) No. 6 (+) — Chassis ground (

−

):

Is the voltage more than 10 V? Go to step 8.

Repair the open or 
ground short cir-
cuit of harness of 
power supply cir-
cuit.

EN(H6DO)(diag)-59

ENGINE (DIAGNOSTICS)

Diagnostics for Engine Starting Failure

8

CHECK INPUT VOLTAGE OF ECM.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM con-
nector and chassis ground.

Connector & terminal

(B135) No. 5 (+) — Chassis ground (

−

):

(B135) No. 6 (+) — Chassis ground (

−

):

Is the voltage more than 10 V? Check ignition 

control system. 
<Ref. to 
EN(H6DO)(diag)-
60, IGNITION 
CONTROL SYS-
TEM, Diagnostics 
for Engine Start-
ing Failure.>

Repair the open or 
ground short cir-
cuit of harness 
between ECM 
connector and 
main relay connec-
tor.

Step

Check

Yes

No

EN(H6DO)(diag)-60

ENGINE (DIAGNOSTICS)

Diagnostics for Engine Starting Failure

D: IGNITION CONTROL SYSTEM

CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H6DO)(diag)-41, 
OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H6DO)(diag)-34, PROCEDURE, 
Inspection Mode.>.
WIRING DIAGRAM:

Step

Check

Yes

No

1

CHECK SPARK PLUG CONDITION.
1) Remove the spark plug. <Ref. to 
IG(H6DO)-4, REMOVAL, Spark Plug.>
2) Check the spark plug condition. <Ref. to 
IG(H6DO)-5, INSPECTION, Spark Plug.>

Is the spark plug’s status OK?

Go to step 2.

Replace the spark 
plug.

E34

E45

E31

E32

E46

E33

1
2
3

ECM

B135

13

17

18

15

14

16

SBF-7

B327

MAIN
RELAY 2

E46

E2

B21

E32

18

14

13

16

17

3

2

3

1

2

E34

3

2

E45

3

2

15

49

1

1

1

E31

IGNITION COIL

No. 1

IGNITION COIL

No. 2

IGNITION COIL

No. 3

IGNITION COIL

No. 4

IGNITION COIL

No. 5

IGNITION COIL

No. 6

3

1

2

E33

3

1

2

EN-03491

1

2

RELAY
HOLDER

B225

B21

1 2 3 4

12 13 14 15

5 6 7 8

16 17 18 19

9 10 11

20 21 22

23 24 25 26 27 28 29 30 31 32 33

35

34

37

36

39

38

41

40

43

42

44

45

47

46

49

48

51

50

53

52

54

9

10

1

2

3

4

5

6

7

8

11 12

14

15 16

13

18

19 20

17

22

23 24

21

38

39 40

37

34

35 36

33

30

31 32

29

26

27 28

25

B225

B135

5

6

7

8

2

1

9

4

3

10

24

22 23

25

11 12 13 14 15

26 27

28

16 17 18 19

20 21

29 30 31

32 33

34 35

B327

3

4

1

2

5

6

E

E

6

4

BATTERY