Subaru Impreza 3 / Impreza WRX / Impreza WRX STI. Manual — part 230

EN(H4DOTC)(diag)-144

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

2

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:

Is the resistance 1 MΩ or
more?

Replace the elec-
tronic throttle con-
trol. <Ref. to
FU(STI)-15, Throt-
tle Body.> <Ref. to
FU(w/o STI)-15,
Throttle Body.>

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).>

Step

Check

Yes

No

EN(H4DOTC)(diag)-145

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

AA:DTC P0123 THROTTLE/PEDAL POSITION SENSOR/SWITCH “A” CIRCUIT

HIGH

DTC DETECTING CONDITION:

• Immediately at fault recognition

• GENERAL DESCRIPTION <Ref. to GD(H4DOTC)-59, DTC P0123 THROTTLE/PEDAL POSITION SEN-

SOR/SWITCH “A” CIRCUIT HIGH, Diagnostic Trouble Code (DTC) Detecting Criteria.>

TROUBLE SYMPTOM:

• Improper idling

• Engine stalls.

• Poor driving performance
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.>.

EN(H4DOTC)(diag)-146

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 HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
electronic throttle control.
3) Measure the resistance of harness between
ECM connector and electronic throttle control
connector.

Connector & terminal

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

Is the resistance less than 1 Ω? Go to step

2.

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

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)-147

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

2

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

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
ECM connector
• Poor contact of
coupling connector

3

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 (–):

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

4.

4

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:

Is the resistance 1 MΩ or
more?

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.>

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

Step

Check

Yes

No