Subaru Legacy (2005 year). Manual - part 236

EN(H4SO 2.5)(diag)-229

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

21

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

Connector & terminal

(B136) No. 18 — (B136) No. 16:
(B136) No. 29 — (B136) No. 16:

Is the resistance more than 1 
M

Ω?

Go to step 22.

Repair the short 
circuit to sensor 
power supply.

22

CHECK SENSOR OUTPUT.
1) Turn the ignition switch to OFF.
2) Connect the connectors except for electric 
throttle control relay.
3) Turn the ignition switch to ON.
4) Read the data of main throttle sensor signal 
using Subaru Select Monitor.

NOTE:

For detailed operation procedure, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(H4SO 2.5)(diag)-25, Subaru Select Mon-
itor.>

Is the voltage 0.81 — 0.87 V?

Go to step 23.

Repair the poor 
contact of elec-
tronic throttle con-
trol connector. 
Replace the elec-
tronic throttle con-
trol if defective.

23

CHECK SENSOR OUTPUT.
Read the data of sub throttle sensor signal 
using Subaru Select Monitor.

NOTE:

For detailed operation procedure, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(H4SO 2.5)(diag)-25, Subaru Select Mon-
itor.>

Is the voltage 1.64 — 1.70 V?

Go to step 24.

Repair the poor 
contact in ECM 
connector. 
Replace the elec-
tronic throttle con-
trol if defective.

24

CHECK HARNESS BETWEEN ECM AND 
ELECTRONIC THROTTLE CONTROL MO-
TOR.
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

(B137) No. 5 — (E57) No. 2:
(B137) No. 4 — (E57) No. 1:

Is the resistance less than 1 
Ω?

Go to step 25.

Repair the open 
circuit of harness 
connector.

25

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 less than 5 V?

Go to step 26.

Repair the power 
supply short cir-
cuit of harness 
between ECM and 
electronic throttle 
control.

Step

Check

Yes

No

EN(H4SO 2.5)(diag)-230

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

CC:DTC P2102 THROTTLE ACTUATOR CONTROL MOTOR CIRCUIT LOW

DTC DETECTING CONDITION:
Immediately at fault recognition
TROUBLE SYMPTOM:
• Erroneous idling
• Poor driving performance
• Engine stalls.

CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4SO 2.5)(diag)-
40, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4SO 2.5)(diag)-33, Inspection Mode.>.

26

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

Connector & terminal

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

Is the resistance more than 1 
M

Ω?

Go to step 27.

Repair the short 
circuit of harness.

27

CHECK ELECTRONIC THROTTLE CON-
TROL MOTOR HARNESS.
Measure the resistance between electronic 
throttle control connector terminals.

Connector & terminal

(E57) No. 2 — (E57) No. 1:

Is the resistance more than 1 
M

Ω?

Go to step 28.

Repair the short 
circuit of harness.

28

CHECK ELECTRONIC THROTTLE CON-
TROL GROUND CIRCUIT.
Measure the resistance between ECM connec-
tor and chassis ground.

Connector & terminal

(B137) No. 3 — Chassis ground:

Is the resistance less than 5 
Ω?

Go to step 29.

Repair the open 
circuit of harness.

29

CHECK ELECTRONIC THROTTLE CON-
TROL.
Measure the resistance between electronic 
throttle control terminals.

Terminals

No. 1 — No. 2:

Is the resistance less than 5 
Ω?

Go to step 30.

Replace the elec-
tronic throttle con-
trol.

30

CHECK ELECTRONIC THROTTLE CON-
TROL.
Move the throttle valve to the fully open and 
fully closed positions with fingers.
Check that the valve returns to the specified 
position when releasing fingers.

Does the valve return to the 
specified position? Specifica-
tion: 3 mm (0.12 in) from fully 
closed position

Repair the poor 
contact in ECM 
connector. 
Replace the ECM 
if defective. <Ref. 
to FU(H4SO 2.5)-
37, Engine Con-
trol Module 
(ECM).>

Replace the elec-
tronic throttle con-
trol.

Step

Check

Yes

No

EN(H4SO 2.5)(diag)-231

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

WIRING DIAGRAM:
• EC, EK, EH, ER and K4 model

• KA and KS model

NOTE:
Fuel injection system for KA and KS model is the same as 2.0 L model. Refer to EN(H4SO 2.0) section.

EN-03512

B362

E57

B362

B20

B21

E57

B122

B83

B138

1 2

7 8

3
4

5
6

1 2 3 4 5 6 7 8 9 10 11

12 13 14 15 16 17 18 19 20 21 22
23 24 25

34 35

36 37 38 39 40 41

48 49

50 51 52 53 54

42 43

44 45

46 47

26 27 28 29 30 31 32 33

1 2 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

2

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

7

32 33 34 35

B135

B:

B136

C:

B137

D:

BATTERY

MAIN RELAY

ELECTRONIC
THROTTLE 
CONTROL RELAY

ELECTRONIC
THROTTLE CONTROL

SBF-7

B135

B:

B137

B136

D:

E1

B20

B83

C:

E

E

E

D6

B35

38

39

20

19

16

15

E2

B21

4

6

1

2

3

5

D4

D5

C35

C16

B1

B4

D1

D2

D3

36

35

37

C29

C18

ECM

5

8

7

6

36

B21

E2

E

B122 : RHD

B138 : LHD

1 2 3 4 5 6

B138 : RHD

B122 : LHD

1 2 3 4
5 6 7 8
9 10 11 12

14

13

15 16

*

: TERMINAL No. RANDOM ARRANGEMENT

1

*

: TERMINAL No. RANDOM ARRANGEMENT
  AMONG 1,2,5, AND 6

2

*

1

*

2

*

1

*

1

*

1

*

2

EN(H4SO 2.5)(diag)-232

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

Step

Check

Yes

No

1

CHECK OPTION CODE.

Is the option code EC, EK, EH, 
ER or K4?

Go to step 2.

Refer to EN(H4SO 
2.0) section. <Ref. 
to EN(H4SO 
2.0)(diag)-64, List 
of Diagnostic Trou-
ble Code (DTC).>

NOTE:
Fuel injection sys-
tem for KA and KS
model is the same
as 2.0 L model.

2

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. 5 and 
No. 6 of electronic throttle control relay.
4) Measure the resistance between electronic 
throttle control relay terminals.

Terminals

No. 7 — No. 8:

Is the resistance less than 1 
Ω?

Go to step 3.

Replace the elec-
tronic throttle con-
trol relay.

3

CHECK POWER SUPPLY OF ELECTRONIC 
THROTTLE CONTROL RELAY.
1) Turn the ignition switch to ON.
2) Measure the voltage between electronic 
throttle control relay connector and chassis 
ground.

Connector & terminal

(B362) No. 8 (+) — Chassis ground (

−

):

(B362) No. 5 (+) — Chassis ground (

−

):

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

Repair the open or 
ground short cir-
cuit of power sup-
ply circuit.

4

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

Connector & terminal

(B362) No. 6 (+) — Chassis ground (

−

):

Is the voltage more than 10 V? Repair the power 

supply short cir-
cuit of harness 
between ECM and 
electronic throttle 
control relay.

Go to step 5.

5

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

Connector & terminal

(B362) No. 6 — Chassis ground:
(B362) No. 7 — Chassis ground:

Is the resistance more than 1 
M

Ω?

Go to step 6.

Repair the ground 
short circuit of har-
ness between 
ECM and elec-
tronic throttle con-
trol relay.

6

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

Connector & terminal

(B135) No. 35 — (B362) No. 6:
(B137) No. 6 — (B362) No. 7:

Is the resistance less than 1 
Ω?

Repair the poor 
contact in ECM 
connector. 
Replace the ECM 
if defective. <Ref. 
to FU(H4SO 2.5)-
37, Engine Con-
trol Module 
(ECM).>

Repair the open 
circuit of harness 
between ECM and 
electronic throttle 
control relay.