Subaru Legacy (2005 year). Service manual - part 242

EN(H4SO 2.5)(diag)-253

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

7

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 8.

Replace the accel-
erator pedal posi-
tion sensor.

8

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

Terminals

No. 1 — No. 6:

Is the resistance 0.75 — 3.15 
k

Ω?

Go to step 9.

Replace the accel-
erator pedal posi-
tion sensor.

9

CHECK ACCELERATOR PEDAL POSITION 
SENSOR.
Measure the resistance of accelerator pedal 
position sensor without depressing the accel-
erator pedal.

Terminals

No. 5 — No. 4:

Is the resistance 0.2 — 0.8 
k

Ω?

Go to step 10.

Replace the accel-
erator pedal posi-
tion sensor.

10

CHECK ACCELERATOR PEDAL POSITION 
SENSOR.
Measure the resistance of accelerator pedal 
position sensor without depressing the accel-
erator pedal.

Terminals

No. 2 — No. 6:

Is the resistance 0.15 — 0.63 
k

Ω?

Go to step 11.

Replace the accel-
erator pedal posi-
tion sensor.

11

CHECK ACCELERATOR PEDAL POSITION 
SENSOR.
Measure the resistance of accelerator pedal 
position sensor with depressing the accelera-
tor pedal.

Terminals

No. 5 — No. 4:

Is the resistance 0.5 — 2.5 
k

Ω?

Go to step 12.

Replace the accel-
erator pedal posi-
tion sensor.

12

CHECK ACCELERATOR PEDAL POSITION 
SENSOR.
Measure the resistance of accelerator pedal 
position sensor with depressing the accelera-
tor pedal.

Terminals

No. 2 — No. 6:

Is the resistance 0.28 — 1.68 
k

Ω?

Go to step 13.

Replace the accel-
erator pedal posi-
tion sensor.

13

CHECK ACCELERATOR PEDAL POSITION 
SENSOR OUTPUT.
1) Turn the ignition switch to OFF.
2) Connect all the connectors.
3) Turn the ignition switch to ON.
4) Read the data of main throttle sensor signal 
and sub accelerator pedal position sensor sig-
nal 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 less than 4.8 V? Go to step 14.

Go to step 15.

14

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

Is there poor contact?

Repair the poor 
contact.

Go to step 19.

Step

Check

Yes

No

EN(H4SO 2.5)(diag)-254

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

CL:DTC P2503 CHARGING SYSTEM VOLTAGE LOW

NOTE:
For the diagnostic procedure, refer to DTC P2504. <Ref. to EN(H4SO 2.5)(diag)-255, DTC P2504 CHARG-
ING SYSTEM VOLTAGE HIGH, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>

15

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. 34 — (B315) No. 4:
(B136) No. 35 — (B315) No. 6:

Is the resistance less than 1 
Ω?

Go to step 16.

Repair the open 
circuit of harness 
connector.

16

CHECK HARNESS BETWEEN ECM AND AC-
CELERATOR PEDAL POSITION SENSOR.
1) Connect the ECM connector.
2) Measure the resistance between accelera-
tor pedal position sensor connector and engine 
ground.

Connector & terminal

(B315) No. 4 — Engine ground:
(B315) No. 6 — Engine ground:

Is the resistance less than 5 
Ω?

Go to step 17.

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

17

CHECK HARNESS BETWEEN ECM AND AC-
CELERATOR 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 engine 
ground.

Connector & terminal

(B315) No. 5 (+) — Engine ground (

−

):

(B315) No. 2 (+) — Engine ground (

−

):

Is the voltage less than 6 V?

Go to step 18.

Repair the battery 
short circuit of har-
ness between 
ECM connector 
and accelerator 
pedal position sen-
sor connector.

18

CHECK HARNESS BETWEEN ECM AND AC-
CELERATOR PEDAL POSITION SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM con-
nectors.

Connector & terminal

(B136) No. 17 — (B136) No. 15:
(B136) No. 17 — (B136) No. 16:
(B136) No. 28 — (B136) No. 15:
(B136) No. 28 — (B136) No. 16:

Is the resistance more than 1 
M

Ω?

Go to step 19.

Repair the short 
circuit to sensor 
power supply.

19

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 connector 
terminals of accelerator pedal position sensor.

Connector & terminal

(B315) No. 5 — (B315) No. 2:

Is the resistance more than 1 
M

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 short 
circuit of harness 
between ECM 
connector and 
accelerator pedal 
position sensor 
connector.

Step

Check

Yes

No

EN(H4SO 2.5)(diag)-255

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

CM:DTC P2504 CHARGING SYSTEM VOLTAGE HIGH

DTC DETECTING CONDITION:
Immediately at fault recognition

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.>.
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-02465

B134

F26

B134

F26

ECM

GENERATOR

22

3

1 2 3

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

EN(H4SO 2.5)(diag)-256

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 HARNESS BETWEEN GENERATOR 
AND ECM CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from generator 
and ECM.
3) Measure the resistance of harness 
between generator connector and engine 
ground.

Connector & terminal

(F26) No. 3 — Engine ground:

Is the resistance more than 1 
M

Ω?

Go to step 3.

Repair the ground 
short circuit of har-
ness between 
ECM and purge 
control solenoid 
valve connector.

3

CHECK HARNESS BETWEEN GENERATOR 
AND ECM CONNECTOR.
Measure the resistance of harness between 
ECM and generator.

Connector & terminal

(B134) No. 22 — (F26) No. 3:

Is the resistance less than 1 
Ω?

Repair the poor 
contact in connec-
tor.

Repair the open 
circuit of harness 
between ECM and 
generator connec-
tor.

NOTE:
In this case, repair
the following:
• Open circuit of 
harness between 
ECM and genera-
tor connector
• Poor contact in 
coupling connector