Subaru Legacy (2005 year). Manual - part 320

EN(H4DOTC)(diag)-49

ENGINE (DIAGNOSTICS)

Diagnostics for Engine Starting Failure

16.Diagnostics for Engine Starting Failure

A: PROCEDURE

1. Check for fuel amount.

↓

2. Inspection of starter motor circuit. <Ref. to EN(H4DOTC)(diag)-50, STARTER MOTOR CIRCUIT, Diagnostics for Engine Start-
ing Failure.>

↓

3. Inspection of ECM power supply and ground line. <Ref. to EN(H4DOTC)(diag)-53, CHECK POWER SUPPLY AND GROUND 
LINE OF ENGINE CONTROL MODULE (ECM), Diagnostics for Engine Starting Failure.>

↓

4. Inspection of ignition control system. <Ref. to EN(H4DOTC)(diag)-55, IGNITION CONTROL SYSTEM, Diagnostics for Engine 
Starting Failure.>

↓

5. Inspection of fuel pump circuit. <Ref. to EN(H4DOTC)(diag)-58, FUEL PUMP CIRCUIT, Diagnostics for Engine Starting Fail-
ure.>

↓

6. Inspection of fuel injector circuit. <Ref. to EN(H4DOTC)(diag)-60, FUEL INJECTOR CIRCUIT, Diagnostics for Engine Starting 
Failure.>

EN(H4DOTC)(diag)-50

ENGINE (DIAGNOSTICS)

Diagnostics for Engine Starting Failure

B: STARTER MOTOR CIRCUIT

CAUTION:
After repair or replacement of faulty parts, perform Clear Memory Mode <Ref. to EN(H4DOTC)(diag)-
37, OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4DOTC)(diag)-30, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:

Step

Check

Yes

No

1

CHECK OPERATION OF STARTER MOTOR. Does the starter motor oper-

ate?

Go to step 2.

Go to step 3.

2

CHECK DTC.

Is DTC displayed? <Ref. to 
EN(H4DOTC)(diag)-29, 
OPERATION, Read Diagnos-
tic Trouble Code (DTC).>

Inspect the rele-
vant DTC using 
List of Diagnostic 
Trouble Code 
(DTC). <Ref. to 
EN(H4DOTC)(diag
)-62, List of Diag-
nostic Trouble 
Code (DTC).>

Repair the poor 
contact in ECM 
connector.

EN-03518

No.21

B225

B225

MAIN SBF

SBF-6

E

16

14

15

13

ECM

B137

D:

B135

B:

B137

B72

D:

B135

B:

B32

D8

B72

B14

3

2

M

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 36

39 40

37
38

1

2

9

3

4

5

6

7

8

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

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

32 33

34 35

1

3

4 5 6

2

BATTERY

IGNITION
SWITCH

STARTER RELAY

STARTER MOTOR

EN(H4DOTC)(diag)-51

ENGINE (DIAGNOSTICS)

Diagnostics for Engine Starting Failure

3

CHECK INPUT SIGNAL OF STARTER MO-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from starter 
motor.
3) Turn the ignition switch to START.
4) Measure the power supply voltage between 
starter motor connector terminal and engine 
ground.

Connector & terminal

(B14) No. 1 (+) — Engine ground (

−

):

NOTE:

• For AT model, place the select lever in “P” or 
“N” range.
• For MT model, depress the clutch pedal.

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

Go to step 5.

4

CHECK GROUND CIRCUIT OF STARTER 
MOTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the ground cable terminal from 
starter motor.
3) Measure the resistance of ground cable 
between ground cable terminal and engine 
ground.

Is the resistance less than 5 
Ω?

Check the starter 
motor. <Ref. to 
SC(H4SO 2.0)-6, 
Starter.>

Repair the open 
circuit of ground 
cable.

5

CHECK HARNESS BETWEEN BATTERY 
AND IGNITION SWITCH CONNECTOR.
1) Disconnect the connector from ignition 
switch.
2) Measure the power supply voltage between 
ignition switch connector and chassis ground.

Connector & terminal

(B72) No. 3 (+) — Chassis ground (

−

):

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

Check the follow-
ing and repair if 
necessary.

• Blown out 
fuse
• Open circuit 
of harness 
between igni-
tion switch and 
battery

6

CHECK IGNITION SWITCH.
1) Disconnect the connector from ignition 
switch.
2) Measure the resistance between ignition 
switch terminals after turning the ignition 
switch to START position.

Terminals

No. 2 — No. 3:

Is the resistance less than 5 
Ω?

Go to step 7.

Replace the igni-
tion switch.

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. 14 (+) — Chassis ground (

−

):

(B225) No. 16 (+) — Chassis ground (

−

):

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

Repair the open or 
ground short cir-
cuit of harness 
between starter 
relay and ignition 
switch.

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 
Ω?

Go to step 9.

Replace the 
starter relay.

Step

Check

Yes

No

EN(H4DOTC)(diag)-52

ENGINE (DIAGNOSTICS)

Diagnostics for Engine Starting Failure

9

CHECK INPUT VOLTAGE OF ECM.
1) Turn the ignition switch to OFF.
2) Connect the starter relay connector.
3) Disconnect the connector from ECM.
4) Measure the resistance of harness 
between ECM and starter relay connector.

Connector & terminal

(B135) No. 32 — (B225) No. 15:

Is the resistance less than 1 
Ω?

Go to step 10.

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

10

CHECK INPUT VOLTAGE OF STARTER MO-
TOR.
1) Turn the ignition switch to OFF.
2) Connect the connector to ECM.
3) Turn the ignition switch to START.
4) Measure the voltage between starter motor 
and engine ground.

Connector & terminal

(B14) No. 1 (+) — Engine ground (

−

):

Is the voltage more than 10 V? Go to step 11.

Repair the open or 
ground short cir-
cuit of harness 
between starter 
relay and starter.

11

CHECK HARNESS BETWEEN IGNITION 
SWITCH AND ECM.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ignition 
switch and ECM.
3) Measure the resistance of harness 
between ignition switch and ECM connector.

Connector & terminal

(B137) No. 8 — (B72) No. 2:

Is the resistance less than 1 
Ω?

Check the engine 
control module 
(ECM) power sup-
ply and ground 
line. <Ref. to 
EN(H4DOTC)(diag
)-53, CHECK 
POWER SUPPLY 
AND GROUND 
LINE OF ENGINE 
CONTROL MOD-
ULE (ECM), Diag-
nostics for Engine 
Starting Failure.>

Repair the open 
circuit between 
ignition switch and 
ECM.

Step

Check

Yes

No