Subaru Impreza 3 / Impreza WRX / Impreza WRX STI. Manual — part 213

EN(H4DOTC)(diag)-76

Diagnostics for Engine Starting Failure

ENGINE (DIAGNOSTICS)

3

CHECK DTC.

Is DTC displayed? <Ref. to
EN(H4DOTC)(diag)-48,
OPERATION, Read Diagnostic
Trouble Code (DTC).>

Check the appropri-
ate DTC using the
“List of Diagnostic
Trouble Code
(DTC)”. <Ref. to
EN(H4DOTC)(diag)
-87, List of Diagnos-
tic Trouble Code
(DTC).>

Check ignition con-
trol system. <Ref. to
EN(H4DOTC)(diag)
-80, IGNITION
CONTROL SYS-
TEM, Diagnostics
for Engine Starting
Failure.>

4

CHECK INPUT SIGNAL FOR STARTER MO-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from starter
motor.
3) Depress the clutch pedal.
4) Turn the ignition switch to START.
5) Measure the voltage between the starter
motor connector and the engine ground.

Connector & terminal

(B14) No. 1 (+) — Engine ground (–):

Is the voltage 10 V or more?

Check the starter
motor. <Ref. to
SC(STI)-8,
Starter.>

Go to step

5.

5

CHECK INPUT SIGNAL FOR STARTER MO-
TOR.
1) Depress the clutch pedal.
2) Turn the ignition switch to START.
3) Measure the voltage between starter relay
connector and chassis ground.

Connector & terminal

(B225) No. 10 (+) — Chassis ground (–):

Is the voltage 10 V or more?

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

Go to step

6.

6

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

Connector & terminal

(B72) No. 3 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Go to step

7.

Repair the power
supply circuit.

7

CHECK IGNITION SWITCH.
Measure the resistance between ignition switch
terminals after turning the ignition switch to
START position.

Terminals

No. 2 — No. 3:
No. 6 — No. 3:

Is the resistance less than 1 Ω? Go to step

8.

Replace the igni-
tion switch. <Ref.
to SL-42,
REPLACEMENT,
Ignition Key Lock.>

8

CHECK INPUT VOLTAGE OF CLUTCH
START SWITCH.
1) Turn the ignition switch to OFF.
2) Disconnect the clutch start switch connec-
tor.
3) Connect the connector to ignition switch.
4) Turn the ignition switch to START.
5) Measure the voltage between the clutch
start switch connector and chassis ground.

Connector & terminal

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

Is the voltage 10 V or more?

Go to step

9.

Check the follow-
ing item and repair
if necessary.
• Blown out of fuse
(F/B No. 21)
• Open or short
circuit to ground in
harness between
ignition switch con-
nector and clutch
start switch con-
nector

Step

Check

Yes

No

EN(H4DOTC)(diag)-77

Diagnostics for Engine Starting Failure

ENGINE (DIAGNOSTICS)

9

CHECK HARNESS BETWEEN STARTER RE-
LAY CONNECTOR AND CLUTCH START
SWITCH CONNECTOR.
1) Turn the ignition switch to OFF.
2) Remove the starter relay.
3) Measure the resistance of harness between
starter relay connector and clutch start switch
connector.

Connector & terminal

(B225) No. 11 — (B106) No. 2:

Is the resistance less than 1 Ω? Go to step

10.

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

10

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

Connector & terminal

(B225) No. 11 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Go to step

11.

Replace the clutch
start switch. <Ref.
to CL-33, Clutch
Switch.>

11

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

Connector & terminal

(B225) No. 9 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Go to step

12.

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

12

CHECK STARTER RELAY.
1) Connect the battery to starter relay termi-
nals No. 11 and No. 12.
2) Measure the resistance between starter
relay terminals.

Terminals

No. 9 — No. 10:

Is the resistance less than 1 Ω? Go to step

13.

Replace the starter
relay.

13

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

Connector & terminal

(B136) No. 16 — (B225) No. 10:

Is the resistance less than 1 Ω? Go to step

14.

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

14

CHECK ECM INPUT VOLTAGE.
1) Install the starter relay.
2) Depress the clutch pedal.
3) Turn the ignition switch to START.
4) Measure the voltage between ECM connec-
tor and chassis ground.

Connector & terminal

(B135) No. 26 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Check the ECM
power supply and
ground line. <Ref. to
EN(H4DOTC)(diag)
-78, 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 con-
nector and starter
relay connector.

Step

Check

Yes

No

EN(H4DOTC)(diag)-78

Diagnostics for Engine Starting Failure

ENGINE (DIAGNOSTICS)

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

ULE (ECM)

CAUTION:

After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(H4DOTC)(diag)-63,

OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(H4DOTC)(diag)-49, PROCE-

DURE, Inspection Mode.>.

WIRING DIAGRAM:

• Engine electrical system, without SI-DRIVE <Ref. to WI-32, WITHOUT SI-DRIVE, WIRING DIAGRAM,

Engine Electrical System.>

• Engine electrical system, with SI-DRIVE <Ref. to WI-48, WITH SI-DRIVE, WIRING DIAGRAM, Engine

Electrical System.>

ECM

EN-08715

B136

C:

B72

C1

D7

B13

A3

A6

C2 C30

24

23

22

21

B134

B135

A:

C: B136

D: B137

B:

35

34

40

A4

D3

36

B134

B135

B137

B21

B72

A:

B:

D:

D1

3

1

15A

B220

B220

B220

3

4

18

19

6

7

4

3
5

2

1

12

11

10

9

8

40

36 39

38

37

34

33

35

32

28 31

30

29

23

22

21

20

26

25

24

27

17

16

15

14

13

2

6

5

4

3

1

54

52 53

50 51

48 49

46 47

45

44

42 43

40 41

38 39

36 37

34 35

33

32

31

30

29

28

27

26

25

24

23

22

21

20

11

10

9

19

18

17

16

8

7

6

5

15

14

13

12

4

3

2

1

31

30

29

28

27

21

20

19

18

17

16

26

25

24

15

14

13

12

11

23

22

10

3

4

9

1

2

8

7

6

5

35

34

33

32

31

30

29

21

20

19

18

17

16

28

27

26

15

14

13

12

11

25

23

22

24

10

3

4

9

1

2

8

7

6

5

31

30

32

29

34

33

21

20

19

18

17

16

28

27

26

15

14

13

12

11

25

23

22

24

10

3

4

9

1

2

8

7

6

5

B21

E2

35

27

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

26

33 34

E

E

SBF-7

SBF-6

FUSE

(RELAY BLOCK)

IGNITION

SWITCH

BATTERY

MAIN RELAY

No. 13

No. 12

MAIN SBF

EN(H4DOTC)(diag)-79

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. 23 and No. 24.
4) Measure the resistance between main relay
terminals.

Terminals

No. 21 — No. 22:

Is the resistance less than 1 Ω? Go to step

2.

Replace the main
relay. <Ref. to
FU(STI)-60, Main
Relay.> <Ref. to
FU(w/o STI)-58,
Main Relay.>

2

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

Connector & terminal

(B134) No. 3 — Chassis ground:
(B134) No. 4 — Chassis ground:
(B134) No. 6 — Chassis ground:
(B137) No. 1 — Chassis ground:
(B137) No. 3 — Chassis ground:

Is the resistance less than 5 Ω? Go to step

3.

Repair the harness
and connector.
NOTE:

In this case, repair
the following item:
• Open circuit of
harness between
ECM

connector

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

(B136) No. 2 (+) — Chassis ground (–):
(B136) No. 30 (+) — 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

(B220) No. 21 (+) — Chassis ground (–):
(B220) No. 23 (+) — 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

(B135) No. 13 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Go to step

6.

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

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

(B136) No. 1 (+) — Chassis ground (–):
(B137) No. 7 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Check ignition con-
trol system. <Ref. to
EN(H4DOTC)(diag)
-80, 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 main relay
connector
• Poor contact of
main relay connec-
tor
• Poor contact of
ECM connector