Subaru Legacy (2005 year). Manual - part 356

EN(H4DOTC)(diag)-193

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

BP:DTC P2109 THROTTLE/PEDAL POSITION SENSOR “A” MINIMUM STOP 

PERFORMANCE

NOTE:
For the diagnostic procedure, refer to DTC P2101. <Ref. to EN(H4DOTC)(diag)-183, DTC P2101 THROT-
TLE ACTUATOR CONTROL MOTOR CIRCUIT RANGE/PERFORMANCE, Diagnostic Procedure with Di-
agnostic Trouble Code (DTC).>

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) Measure the resistance between electronic 
throttle control relay terminals.

Terminals

No. 7 — No. 8:

Is the resistance more than 1 
M

Ω?

Go to step 2.

Replace the elec-
tronic throttle con-
trol relay.

2

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

Connector & terminal

(B362) No. 7 (+) — Chassis ground (

−

):

Is the voltage more than 5 V?

Go to step 3.

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

3

CHECK HARNESS BETWEEN ECM AND 
ELECTRONIC THROTTLE CONTROL RE-
LAY.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM con-
nector and chassis ground.

Connector & terminal

(B135) No. 35 — Chassis ground:

Is the resistance more than 1 
M

Ω?

Repair the poor 
contact in ECM 
connector. 
Replace the ECM 
if defective. <Ref. 
to FU(H4DOTC)-
34, Engine Con-
trol Module 
(ECM).>

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

EN(H4DOTC)(diag)-194

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

BQ:DTC P2122 THROTTLE/PEDAL POSITION SENSOR/SWITCH “D” CIRCUIT 

LOW INPUT

DTC DETECTING CONDITION:
Immediately at fault recognition
TROUBLE SYMPTOM:
• Erroneous idling
• Poor driving performance
WIRING DIAGRAM:

EN-03546

B315

B21

E

C:

ECM

B136

B137

D:

C:

B136

B137

D:

B83

B315

*

*

3

5

4

1

2

6

C15

C17

C34

C16

C28

C35

D1

D2

1 2 3 4 5 6

B122

1 2 3 4
5 6 7 8

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

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

MAIN

SUB

ACCELERATOR

PEDAL POSITION

SENSOR

B122

7

4

36

1 2 3 4

12 13 14 15

5 6 7 8

16 17 18 19

9 10 11

20 21 22

23 24 25 26 27 28 29 30 31 32 33

35

34

37

36

39

38

41

40

43

42

44

45

47

46

49

48

51

50

53

52

54

B21

E2

B83

*

: TERMINAL No. RANDOM ARRANGEMENT

EN(H4DOTC)(diag)-195

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

Step

Check

Yes

No

1

CHECK ACCELERATOR PEDAL POSITION 
SENSOR OUTPUT.
1) Turn the ignition switch to ON.
2) Read the data of main accelerator pedal 
position 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 more than 0.4 V? Go to step 2.

Go to step 3.

2

CHECK POOR CONTACT.
Check poor contact in connector between 
ECM and accelerator pedal position sensor.

Is there poor contact?

Repair the poor 
contact.

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

3

CHECK HARNESS BETWEEN ECM AND AC-
CELERATOR PEDAL POSITION SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Disconnect the connectors from accelerator 
pedal position sensor.
4) Measure the resistance between ECM con-
nector and accelerator pedal position sensor 
connector.

Connector & terminal

(B136) No. 17 — (B315) No. 5:
(B136) No. 15 — (B315) No. 3:

Is the resistance less than 1 
Ω?

Go to step 4.

Repair the open 
circuit of harness 
connector.

4

CHECK HARNESS BETWEEN ECM AND AC-
CELERATOR PEDAL POSITION SENSOR.
Measure the resistance between ECM connec-
tor and chassis ground.

Connector & terminal

(B136) No. 17 — Chassis ground:
(B136) No. 15 — Chassis ground:

Is the resistance more than 1 
M

Ω?

Go to step 5.

Repair the chas-
sis short circuit of 
harness.

5

CHECK POWER SUPPLY OF ACCELERA-
TOR PEDAL POSITION SENSOR.
1) Connect the ECM connector.
2) Turn the ignition switch to ON.
3) Measure the voltage between accelerator 
pedal position sensor connector and chassis 
ground.

Connector & terminal

(B315) No. 3 (+) — Chassis ground (

−

):

Is the voltage 4.5 — 5.5 V?

Go to step 6.

Repair the poor 
contact in ECM 
connector. 
Replace the ECM 
if defective. <Ref. 
to FU(H4DOTC)-
34, Engine Con-
trol Module 
(ECM).>

6

CHECK ACCELERATOR PEDAL POSITION 
SENSOR.
Measure the resistance of accelerator pedal 
position sensor.

Terminals

No. 3 — No. 4:

Is the resistance 1.2 — 4.8 
k

Ω?

Go to step 7.

Replace the accel-
erator pedal posi-
tion sensor.

7

CHECK ACCELERATOR PEDAL POSITION 
SENSOR.
Measure the resistance of accelerator pedal 
position sensor.

Terminals

No. 5 — No. 4:

Check the measured value is within the specifi-
cation without depressing the accelerator 
pedal.

Is the resistance 0.2 — 1.0 
k

Ω?

Go to step 8.

Replace the accel-
erator pedal posi-
tion sensor.

EN(H4DOTC)(diag)-196

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

8

CHECK ACCELERATOR PEDAL POSITION 
SENSOR.
Measure the resistance of accelerator pedal 
position sensor.

Terminals

No. 5 — No. 4:

Check the measured value is within the specifi-
cation with the accelerator pedal depressed.

Is the resistance 0.5 — 2.5 
k

Ω?

Repair the poor 
contact in ECM 
connector. 
Replace the ECM 
if defective. <Ref. 
to FU(H4DOTC)-
34, Engine Con-
trol Module 
(ECM).>

Replace the accel-
erator pedal posi-
tion sensor.

Step

Check

Yes

No