Subaru Legacy IV (2008 year). Service manual - part 116

EN(H4SO)(diag)-67

Diagnostics for Engine Starting Failure

ENGINE (DIAGNOSTICS)

7

CHECK INPUT VOLTAGE OF STARTER RE-
LAY.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from starter relay.
3) Connect the connector to ignition switch.
4) Measure the input voltage between starter 
relay connector and chassis ground after turn-
ing the ignition switch to START position.

Connector & terminal

(B225) No. 13 (+) — Chassis ground (–):
(B225) No. 15 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Go to step 8.

Check the follow-
ing item and repair 
if necessary.
• Blown out of fuse
• Open or short 
circuit to ground in 
harness between 
starter relay and 
ignition switch con-
nector

8

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 9.

Replace the starter 
relay.

9

CHECK HARNESS BETWEEN ECM AND 
STARTER RELAY.
1) Disconnect the connectors from ECM.
2) Measure the resistance of harness connec-
tor between ECM and starter relay.

Connector & terminal

(B225) No. 16 — (B136) No. 20:

Is the resistance less than 1 

:? Go to step 10.

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

10

CHECK TRANSMISSION TYPE.

Is the transmission type AT?

Go to step 11.

Go to step 15.

11

CHECK ECM INPUT VOLTAGE.
1) Turn the ignition switch to START.
2) Measure the input voltage between ECM 
and chassis ground.

Connector & terminal

(B136) No. 32 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Go to step 12.

Repair the open 
circuit of harness 
between ECM and 
ignition switch con-
nector.

12

CHECK HARNESS BETWEEN STARTER RE-
LAY AND INHIBITOR SWITCH.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from inhibitor 
switch.
3) Measure the resistance of harness between 
the starter relay and inhibitor switch.

Connector & terminal

(B225) No. 14 — (T7) No. 9:

Is the resistance less than 1 

:? Go to step 13.

Repair the harness 
and connector.

NOTE:
In this case, repair
the following item:
• Open circuit in
harness between
starter relay con-
nector and inhibitor
switch connector
• Poor contact of
coupling connector

13

CHECK HARNESS BETWEEN INHIBITOR 
SWITCH AND STARTER MOTOR.
Measure the resistance of harness between the 
inhibitor switch and starter motor.

Connector & terminal

(T7) No. 6 — (B14) No. 1:

Is the resistance less than 1 

:? Go to step 14.

Repair the harness 
and connector.

NOTE:
In this case, repair
the following item:
• Open circuit in
harness between
inhibitor switch
connector and
starter motor
• Poor contact of
coupling connector

Step

Check

Yes

No

EN(H4SO)(diag)-68

Diagnostics for Engine Starting Failure

ENGINE (DIAGNOSTICS)

14

CHECK INHIBITOR SWITCH.
1) Place the select lever in “P” range or “N” 
range.
2) Measure the resistance between inhibitor 
switch terminals.

Terminals

No. 6 — No. 9:

Is the resistance less than 1 

:? Check the engine 

control module 
(ECM) power sup-
ply and ground 
line. <Ref. to 
EN(H4SO)(diag)-
69, CHECK 
POWER SUPPLY 
AND GROUND 
LINE OF ENGINE 
CONTROL MOD-
ULE (ECM), Diag-
nostics for Engine 
Starting Failure.>

Replace the inhibi-
tor switch. <Ref. to 
4AT-46, Inhibitor 
Switch.>

15

CHECK HARNESS BETWEEN IGNITION 
SWITCH AND CLUTCH START SWITCH.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from clutch start 
switch.
3) Turn the ignition switch to START.
4) Measure the voltage between the clutch 
start switch and chassis ground.

Connector & terminal

(B106) No. 1 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Go to step 16.

Repair the open 
circuit in harness 
between ignition 
switch connector 
and clutch start 
switch.

16

CHECK CLUTCH START SWITCH.
Measure the resistance between clutch start 
switch terminals while depressing the clutch 
pedal.

Terminals

No. 1 — No. 2:

Is the resistance less than 1 

:? Go to step 17.

Replace the clutch 
start switch. <Ref. 
to CL-37, Clutch 
Switch.>

17

CHECK HARNESS BETWEEN ECM AND 
CLUTCH START SWITCH.
Measure the resistance of harness between 
ECM and clutch start switch.

Connector & terminal

(B136) No. 32 — (B106) No. 2:

Is the resistance less than 1 

:? Go to step 18.

Repair the open 
circuit of harness 
between the ECM 
and clutch start 
switch.

18

CHECK HARNESS BETWEEN STARTER RE-
LAY AND STARTER MOTOR.
Measure the resistance of harness between 
starter relay connector and starter motor.

Connector & terminal

(B225) No. 14 — (B14) No. 1:

Is the resistance less than 1 

:? Check the engine 

control module 
(ECM) power sup-
ply and ground 
line. <Ref. to 
EN(H4SO)(diag)-
69, CHECK 
POWER SUPPLY 
AND GROUND 
LINE OF ENGINE 
CONTROL MOD-
ULE (ECM), Diag-
nostics for Engine 
Starting Failure.>

Repair the open 
circuit of the har-
ness between 
starter relay con-
nector and starter 
motor.

Step

Check

Yes

No

EN(H4SO)(diag)-69

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(H4SO)(diag)-50,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(H4SO)(diag)-41, PROCEDURE,
Inspection Mode.>.
WIRING DIAGRAM:

EN-06831

SBF-6

MAIN SBF

SBF-7

B72

No. 12

B47

E2

B21

2
1

4

6

5

3

E

3

1

B134

B135

A:

D: B137

C: B136

B:

3

4

1

2

5

6

B47

No. 13

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:

MAIN RELAY

ECM

TO IGNITION COIL & IGNITOR ASSY

BATTERY

IGNITION
SWITCH

A7

B2

C23

B19

A5

D2

D1

D3

B5

36

34

37

35

D7

52

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

5

6

27

26

33 34 35

B136

C:

E

E

EN(H4SO)(diag)-70

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(H4SO)-40,
Main Relay.>

2

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

Connector & terminal

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

Connector & terminal

(B136) No. 23 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Go to step 6.

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

6

CHECK INPUT VOLTAGE OF ECM.
1) Turn the ignition switch to OFF.
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(H4SO)(diag)-
71, 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 and main re-
lay connector
• Poor contact of
main relay connec-
tor