Subaru Impreza 3 / Impreza WRX / Impreza WRX STI. Manual — part 287

EN(H4DOTC)(diag)-372

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

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.>

Step

Check

Yes

No

1

CHECK ELECTRONIC THROTTLE CON-
TROL RELAY.
1) Turn the ignition switch to OFF.
2) Remove the electronic throttle control relay.
3) Connect the battery to terminals No. 31 and
No. 32 of electronic throttle control relay.
4) Measure the resistance between electronic
throttle control relay terminals.

Terminals

No. 29 — No. 30:

Is the resistance less than 1 Ω? Go to step

2.

Replace the elec-
tronic throttle con-
trol relay. <Ref. to
FU(STI)-64, Elec-
tronic Throttle
Control Relay.>
<Ref. to FU(w/o
STI)-62, Elec-
tronic Throttle
Control Relay.>

ECM

EN-08727

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

B136

C:

B134

A:

36

35

34

40

B17

B7

D3

A29

6

E2

B21

A1

8

C4

A2

8

6

4

25

*

*

B122

24

3

8

39

2

8

A2

A1

A19

A6

A3

D1

A4

3

E57

2

1

5

B134

B220

B220

31

29

32

A:

B137

B136

D:

C:

B135

B:

*

30

21

22

15A

B220

3

4

B135

B:

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

B220

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

B122

8

7

6

5

4

3

2

1

B21

33

32

31

30

29

28

27

26

47

46

45

44

43

42

54

53

52

51

50

49

48

41

40

39

38

37

36

35

34

25

24

23

22

21

20

19

18

17

16

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

D: B137

26

25

24

23

22

18

28

27

17

16

15

14

13

31

30

29

21

20

19

12

11

10

4

3

6

5

9

8

7

2

1

E57

6

5

4

3

2

1

35

34

33

32

7

26

25

24

23

22

18

28

27

17

16

15

14

13

31

30

29

21

20

19

12

11

10

4

3

6

5

9

8

2

1

E

E

E

SBF-7

FUSE

(RELAY BLOCK)

MAIN RELAY

ELECTRONIC THROTTLE

CONTROL RELAY

BATTERY

: TERMINAL No. OPTIONAL ARRANGEMENT

ELECTRONIC THROTTLE

CONTROL

EN(H4DOTC)(diag)-373

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

2

CHECK POWER SUPPLY OF ELECTRONIC
THROTTLE CONTROL RELAY.
Measure the voltage between electronic throttle
control relay connector and chassis ground.

Connector & terminal

(B220) No. 29 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Go to step

3.

Repair the open or
ground short circuit
of power supply
circuit.

3

CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL RE-
LAY CONNECTOR.
1) Disconnect the connector from ECM.
2) Turn the ignition switch to ON.
3) Measure the voltage between electronic
throttle control relay connector and chassis
ground.

Connector & terminal

(B220) No. 32 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Repair the short
circuit to power in
the harness
between ECM con-
nector and elec-
tronic throttle
control relay con-
nector.

Go to step

4.

4

CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL RE-
LAY CONNECTOR.
1) Turn the ignition switch to OFF.
2) Measure the resistance between electronic
throttle control relay connector and chassis
ground.

Connector & terminal

(B220) No. 32 — Chassis ground:
(B220) No. 30 — Chassis ground:

Is the resistance 1 MΩ or
more?

Go to step

5.

Repair the short
circuit to ground in
harness between
ECM connector
and electronic
throttle control
relay connector.

5

CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL RE-
LAY CONNECTOR.
Measure the resistance between ECM connec-
tor and electronic throttle control relay connec-
tor.

Connector & terminal

(B135) No. 17 — (B220) No. 32:
(B135) No. 7 — (B220) No. 30:

Is the resistance less than 1 Ω? Go to step

6.

Repair the open
circuit in harness
between ECM con-
nector and elec-
tronic throttle
control relay con-
nector.

6

CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from electronic
throttle control.
3) Measure the resistance between ECM con-
nector and chassis ground.

Connector & terminal

(B134) No. 19 — Chassis ground:
(B134) No. 18 — Chassis ground:
(B134) No. 18 — (B136) No. 4:
(B134) No. 28 — Chassis ground:

Is the resistance 1 MΩ or
more?

Go to step

7.

Repair the ground
short circuit of har-
ness between
ECM connector
and electronic
throttle control
connector.

Step

Check

Yes

No

EN(H4DOTC)(diag)-374

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

7

CHECK SHORT CIRCUIT INSIDE THE ECM.
1) Connect the connector to ECM.
2) Measure the resistance between electronic
throttle control connector and engine ground.

Connector & terminal

(E57) No. 6 — Engine ground:
(E57) No. 4 — Engine ground:

Is the resistance 1 MΩ or
more?

Go to step

8.

Repair the ground
short circuit of har-
ness between
ECM connector
and electronic
throttle control
connector.
Replace the ECM if
defective. <Ref. to
FU(STI)-59,
Engine Control
Module (ECM).>
<Ref. to FU(w/o
STI)-57, Engine
Control Module
(ECM).>

8

CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL CON-
NECTOR.
1) Disconnect the connector from ECM.
2) Measure the resistance of harness between
ECM connector and electronic throttle control
connector.

Connector & terminal

(B134) No. 18 — (E57) No. 6:
(B134) No. 28 — (E57) No. 4:
(B134) No. 29 — (E57) No. 3:

Is the resistance less than 1 Ω? Go to step

9.

Repair the harness
and connector.
NOTE:

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

connector

and

electronic

throttle

control

connector
• Poor contact of
coupling connector

9

CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL CON-
NECTOR.
1) Connect the connector to ECM.
2) Measure the resistance between electronic
throttle control connector and engine ground.

Connector & terminal

(E57) No. 3 — Engine ground:

Is the resistance less than 5 Ω? Go to step

10.

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
ECM connector
• Poor contact of
coupling connector

10

CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL CON-
NECTOR.
1) Turn the ignition switch to ON.
2) Measure the voltage between electronic
throttle control connector and engine ground.

Connector & terminal

(E57) No. 6 (+) — Engine ground (–):
(E57) No. 4 (+) — Engine ground (–):

Is the voltage 5 V or more?

Repair the short
circuit to power in
the harness
between ECM con-
nector and elec-
tronic throttle
control connector.

Go to step

11.

Step

Check

Yes

No

EN(H4DOTC)(diag)-375

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

11

CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM con-
nectors.

Connector & terminal

(B134) No. 19 — (B134) No. 18:
(B134) No. 19 — (B134) No. 28:

Is the resistance 1 MΩ or
more?

Go to step

12.

Repair the short
circuit to power in
the harness
between ECM con-
nector and elec-
tronic throttle
control connector.

12

CHECK SENSOR OUTPUT.
1) Connect all connectors.
2) Start the engine and warm up completely.
3) Stop the engine, and then turn the ignition
switch to ON (engine OFF).
4) Read the value of «Main-Throttle Sensor»
using Subaru Select Monitor.
NOTE:

For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(H4DOTC)(diag)-40, Subaru Select Moni-
tor.>

Is the value of «Main-Throttle
Sensor» 0.81 — 0.87 V?

Go to step

13.

Repair the poor
contact of elec-
tronic throttle con-
trol connector.
Replace the elec-
tronic throttle con-
trol if defective.
<Ref. to FU(STI)-
15, Throttle Body.>
<Ref. to FU(w/o
STI)-15, Throttle
Body.>

13

CHECK SENSOR OUTPUT.
Read the value of «Sub-Throttle Sensor» using
Subaru Select Monitor.
NOTE:

For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(H4DOTC)(diag)-40, Subaru Select Moni-
tor.>

Is the value of «Sub-Throttle
Sensor» 1.64 — 1.70 V?

Go to step

14.

Repair the poor
contact of elec-
tronic throttle con-
trol connector.
Replace the elec-
tronic throttle con-
trol if defective.
<Ref. to FU(STI)-
15, Throttle Body.>
<Ref. to FU(w/o
STI)-15, Throttle
Body.>

14

CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL MO-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
electronic throttle control.
3) Measure the resistance between ECM con-
nector and electronic throttle control connector.

Connector & terminal

(B134) No. 2 — (E57) No. 2:
(B134) No. 1 — (E57) No. 1:

Is the resistance less than 1 Ω? Go to step

15.

Repair the harness
and connector.
NOTE:

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

connector

and

electronic

throttle

control

connector
• Poor contact of
coupling connector

15

CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL MO-
TOR.
1) Connect the connector to ECM.
2) Turn the ignition switch to ON.
3) Measure the voltage between electronic
throttle control connector and engine ground.

Connector & terminal

(E57) No. 2 (+) — Engine ground (–):
(E57) No. 1 (+) — Engine ground (–):

Is the voltage 5 V or more?

Repair the short
circuit to power in
the harness
between ECM con-
nector and elec-
tronic throttle
control connector.

Go to step

16.

Step

Check

Yes

No