Subaru Legacy (2005 year). Manual - part 337

EN(H4DOTC)(diag)-117

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

Step

Check

Yes

No

1

CHECK SENSOR OUTPUT.
1) Turn the ignition switch to ON.
2) Read the data of sub throttle sensor signal 
using Subaru Select Monitor.

NOTE:

• Subaru Select Monitor
For detailed operation procedure, refer to 
“READ CURRENT DATA FOR ENGINE”. <Ref. 
to EN(H4DOTC)(diag)-24, Subaru Select Mon-
itor.>

Is the voltage less than 4.73 
V?

Go to step 2.

Go to step 3.

2

CHECK POOR CONTACT.
Check poor contact in connector between 
ECM and electronic throttle control.

Is there poor contact in con-
nector between ECM and elec-
tronic throttle control?

Repair the poor 
contact.

Temporary poor 
contact occurred, 
but it is normal at 
present.

3

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

Connector & terminal

(B136) No. 35 — (E57) No. 3:
(B136) No. 29 — (E57) No. 4:

Is the resistance less than 1 
Ω?

Go to step 4.

Repair the open 
circuit of harness 
connector.

4

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

Connector & terminal

(E57) No. 4 (+) — Engine ground (

−

):

Is the voltage less than 10 V?

Go to step 5.

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

5

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

Connector & terminal

(B136) No. 29 — (B136) No. 16:

Is the resistance more than 1 
M

Ω?

Repair the poor 
contact. Replace 
the electronic 
throttle control.

Sensor power sup-
ply circuit may be 
shorted.

EN(H4DOTC)(diag)-118

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

X: DTC P0230 FUEL PUMP PRIMARY CIRCUIT

DTC DETECTING CONDITION:
Immediately at fault recognition

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:

EN-03582

E

E

M

10

7

6

5

6

No.31

B362

R122

B135

B:

B137

D:

R58

B98

7

D28

B27

1

2

9

8

5

6

5

R2

4

R2

B98

FUEL PUMP
CONTROL UNIT

FUEL
PUMP

ECM

BATTERY

FUEL PUMP
RELAY

B135

B137

B362

B98

R58

2

5

4
6

1
3

B:

D:

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

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

R122

3 4

1 2
5

8 9 10

6 7

1

2 3

4 5 6 7 8

5
6

7 8

3
4

1 2

EN(H4DOTC)(diag)-119

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

Step

Check

Yes

No

1

CHECK POWER SUPPLY CIRCUIT TO FUEL 
PUMP CONTROL UNIT.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from fuel pump 
control unit.
3) Turn the ignition switch to ON.
4) Measure the voltage between fuel pump 
control unit and chassis ground.

Connector & terminal

(R122) No. 10 (+) — Chassis ground (

−

):

Is the voltage more than 10 V? Go to step 2.

Repair the power 
supply circuit.

NOTE:
In this case, repair
the following:
• Open or ground 
short circuit of har-
ness between fuel 
pump relay and 
fuel pump control 
unit
• Poor contact in 
fuel pump control 
unit connector
• Poor contact in 
fuel pump relay 
connector

2

CHECK GROUND CIRCUIT OF FUEL PUMP 
CONTROL UNIT.
1) Turn the ignition switch to OFF.
2) Measure the resistance of harness 
between fuel pump control unit and chassis 
ground.

Connector & terminal

(R122) No. 5 — Chassis ground:

Is the resistance less than 5 
Ω?

Go to step 3.

Repair the har-
ness and connec-
tor.

NOTE:
In this case, repair
the following:
• Open circuit 
between fuel pump 
control unit and 
chassis ground
• Poor contact in 
fuel pump control 
unit connector

3

CHECK HARNESS BETWEEN FUEL PUMP 
CONTROL UNIT AND FUEL PUMP CONNEC-
TOR.
1) Disconnect the connector from fuel pump.
2) Measure the resistance of harness 
between fuel pump control unit and fuel pump 
connector.

Connector & terminal

(R122) No. 7 — (R58) No. 5:
(R122) No. 6 — (R58) No. 6:

Is the resistance less than 1 
Ω?

Go to step 4.

Repair the open 
circuit between 
fuel pump control 
unit and fuel 
pump.

4

CHECK HARNESS BETWEEN FUEL PUMP 
CONTROL UNIT AND FUEL PUMP CONNEC-
TOR.
Measure the resistance of harness between 
fuel pump control unit and chassis ground.

Connector & terminal

(R122) No. 7 — Chassis ground:
(R122) No. 6 — Chassis ground:

Is the resistance more than 1 
M

Ω?

Go to step 5.

Repair the ground 
short circuit 
between fuel pump 
control unit and 
fuel pump.

EN(H4DOTC)(diag)-120

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

5

CHECK HARNESS BETWEEN FUEL PUMP 
CONTROL UNIT AND ECM CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness 
between fuel pump control unit and ECM con-
nector.

Connector & terminal

(R122) No. 9 — (B137) No. 28:
(R122) No. 8 — (B135) No. 27:

Is the resistance less than 1 
Ω?

Go to step 6.

Repair the har-
ness and connec-
tor.

NOTE:
In this case, repair
the following:
• Open circuit 
between fuel pump 
control unit and 
ECM
• Poor contact in 
fuel pump control 
unit and ECM con-
nector

6

CHECK HARNESS BETWEEN FUEL PUMP 
CONTROL UNIT AND ECM CONNECTOR.
Measure the resistance of harness between 
fuel pump control unit and chassis ground.

Connector & terminal

(R122) No. 9 — Chassis ground:
(R122) No. 8 — Chassis ground:

Is the resistance more than 1 
M

Ω?

Go to step 7.

Repair the ground 
short circuit 
between fuel pump 
control unit and 
ECM.

7

CHECK POOR CONTACT.
Check poor contact in ECM and fuel pump 
control unit connector.

Is there poor contact in ECM 
and fuel pump control unit con-
nector?

Repair the poor 
contact in ECM 
and fuel pump 
control unit.

Go to step 8.

8

CHECK EXPERIENCE OF RUNNING OUT OF 
FUEL.

Has the vehicle experienced 
running out of fuel?

Finish the diagno-
sis.

NOTE:
DTC may be re-
corded as a result
of fuel pump idling
while running out
of fuel.

Replace the fuel 
pump control unit. 
<Ref. to 
FU(H4DOTC)-38, 
Fuel Pump Control 
Unit.>

Step

Check

Yes

No