Subaru Legacy IV (2008 year). Manual - part 524

EN(H6DO)(diag)-69

Diagnostics for Engine Starting Failure

ENGINE (DIAGNOSTICS)

8

CHECK INPUT VOLTAGE OF STARTER RE-
LAY.
1) Remove the starter relay.
2) Connect the connector to ignition switch.
3) Turn the ignition switch to START.
4) Measure the voltage between starter relay 
connector and chassis ground.

Connector & terminal

(B225) No. 13 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Go to step 9.

Repair the open 
circuit of harness 
between starter 
relay connector 
and ignition switch 
connector.

9

CHECK STARTER RELAY.
1) Connect the battery to starter relay termi-
nals No. 15 and No. 16.
2) Measure the resistance between starter 
relay terminals.

Terminals

No. 13 — No. 14:

Is the resistance less than 1 

:? Go to step 10.

Replace the starter 
relay.

10

CHECK HARNESS BETWEEN ECM AND 
STARTER RELAY CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM.
3) Measure the resistance of harness between 
ECM and starter relay connector.

Connector & terminal

(B136) No. 20 — (B225) No. 16:

Is the resistance less than 1 

:? Go to step 11.

Repair the open 
circuit of harness 
between ECM and 
starter relay con-
nector.

11

CHECK INPUT VOLTAGE OF STARTER RE-
LAY.
1) Connect the connector to ECM.
2) Place the select lever in “P” range or “N” 
range.
3) Turn the ignition switch to START.
4) Measure the voltage between starter relay 
connector and chassis ground.

Connector & terminal

(B225) No. 15 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Go to step 12.

Go to step 13.

12

CHECK HARNESS BETWEEN ECM AND IN-
HIBITOR RELAY CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the inhibitor relay connector.
3) Measure the resistance of harness between 
ECM and inhibitor relay connector.

Connector & terminal

(B136) No. 31 — (B226) No. 7:
(B136) No. 32 — (B226) No. 10:

Is the resistance less than 1 

:? Check the ECM 

power supply and 
ground line. <Ref. 
to
EN(H6DO)(diag)-
71, CHECK 
POWER SUPPLY 
AND GROUND 
LINE OF ENGINE 
CONTROL MOD-
ULE (ECM), Diag-
nostics for Engine 
Starting Failure.>

Repair the open 
circuit of harness 
between ECM and 
inhibitor relay con-
nector.

13

CHECK INPUT VOLTAGE OF INHIBITOR RE-
LAY.
1) Turn the ignition switch to OFF.
2) Disconnect the inhibitor relay connector.
3) Turn the ignition switch to START.
4) Measure the voltage between inhibitor relay 
connector and chassis ground.

Connector & terminal

(B226) No. 9 (+) — Chassis ground (–):
(B226) No. 11 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Go to step 14.

Check the follow-
ing item and repair 
if necessary.
• Blown out of fuse
• Open or ground 
short circuit of har-
ness between igni-
tion switch 
connector and 
inhibitor relay con-
nector

Step

Check

Yes

No

EN(H6DO)(diag)-70

Diagnostics for Engine Starting Failure

ENGINE (DIAGNOSTICS)

14

CHECK INHIBITOR RELAY.
1) Connect the battery to inhibitor relay termi-
nals No. 7 and No. 9.
2) Measure the resistance between inhibitor 
relay terminals.

Terminals

No. 10 — No. 11:

Is the resistance less than 1 

:? Go to step 15.

Replace the inhibi-
tor relay.

15

CHECK HARNESS BETWEEN INHIBITOR 
RELAY CONNECTOR AND STARTER RE-
LAY CONNECTOR.
1) Turn the ignition switch to OFF.
2) Measure the resistance of harness between 
inhibitor relay connector and starter relay con-
nector.

Connector & terminal

(B226) No. 10 — (B225) No. 15:

Is the resistance less than 1 

:? Repair the open 

circuit of harness 
between TCM and 
inhibitor relay con-
nector.

Repair the open 
circuit of harness 
between inhibitor 
relay connector 
and starter relay 
connector.

Step

Check

Yes

No

EN(H6DO)(diag)-71

Diagnostics for Engine Starting Failure

ENGINE (DIAGNOSTICS)

C: CHECK POWER SUPPLY AND GROUND LINE OF ENGINE CONTROL MODULE 

(ECM)

CAUTION:
After repair or replacement of faulty parts, perform Clear Memory Mode <Ref. to EN(H6DO)(diag)-52,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(H6DO)(diag)-44, PROCEDURE,
Inspection Mode.>.
WIRING DIAGRAM:

SBF-6

MAIN SBF

SBF-7

B72

A7

B2

C23

A3

D2

D1

D7

B5

B19

No. 12

B47

E2

B21

1

2

4

6

5

3

ECM

E

E

3

1

B134

B135

A:

C: B136

D: B137

B:

35

34

52

3

4

1

2

5

6

B47

TO OXYGEN SENSOR

No. 13

A5

36

B72

1

3

4 5 6

2

E

SBF-5

D3

37

MAIN RELAY

BATTERY

IGNITION
SWITCH

EN-06864

B21

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

42

43

36

37

38

39

48

49

50

51

52

53

54

40

41

44

45

46

47

16

10 11 12 13

14 15
25

24

30

9

8

7

17 18 19 20
28

21 22 23

29

32

31

1

2

3

4

6

5

27

26

33 34 35

B136

C:

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

B134

A:

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

B135

B:

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

B137

D:

EN(H6DO)(diag)-72

Diagnostics for Engine Starting Failure

ENGINE (DIAGNOSTICS)

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.

Terminals

No. 3 — No. 5:
No. 4 — No. 6:

Is the resistance less than 1 

:? Go to step 2.

Replace the main 
relay. <Ref. to 
FU(H6DO)-39, 
Main Relay.>

2

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

Connector & terminal

(B134) No. 3 — Chassis ground:
(B134) No. 5 — 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 

:? Go to step 3.

Repair the harness 
and connector.

NOTE:
In this case, repair
the following item:
• Open circuit of
harness between
ECM and engine
ground
• Poor contact of
coupling connector

3

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

Connector & terminal

(B135) No. 5 (+) — Chassis ground (–):
(B135) No. 19 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Go to step 4.

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

4

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

Connector & terminal

(B47) No. 2 (+) — Chassis ground (–):
(B47) No. 5 (+) — Chassis ground (–):
(B47) No. 6 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Go to step 5.

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

5

CHECK HARNESS BETWEEN ECM AND 
MAIN RELAY CONNECTOR.
1) Turn the ignition switch to OFF.
2) Measure the resistance of harness between 
ECM connector and fuel pump relay connector.

Connector & terminal

(B136) No. 23 — (B47) No. 1:

Is the resistance less than 1 

:? Go to step 6.

Repair the open 
circuit of harness 
between ECM con-
nector and main 
relay connector.

6

CHECK INPUT VOLTAGE OF ECM.
1) Install the main relay.
2) Connect the connector to ECM.
3) Turn the ignition switch to ON.
4) Measure the voltage between ECM connec-
tor and chassis ground.

Connector & terminal

(B134) No. 7 (+) — Chassis ground (–):
(B135) No. 2 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Check ignition con-
trol system. <Ref. 
to
EN(H6DO)(diag)-
73, IGNITION 
CONTROL SYS-
TEM, Diagnostics 
for Engine Starting 
Failure.>

Repair the harness 
and connector.

NOTE:
In this case, repair
the following item:
• Open circuit in
harness between
ECM connector
and fuel injector
connector
• Poor contact of
main relay connec-
tor