Subaru Legacy III (2000-2003 year). Manual - part 130

EN(H4SO)-132

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

6

CHECK HARNESS BETWEEN ECM AND 
THROTTLE POSITION SENSOR CONNEC-
TOR.
1) Turn ignition switch to OFF.
2) Disconnect connectors from throttle posi-

tion sensor.

3) Turn ignition switch to ON.
4) Measure voltage between throttle position 

sensor connector and engine ground.

Connector & terminal

(E13) No. 4 (+) — Engine ground (

−−−−

):

Does the measured value exceed the spec-
ified value?

4.5 V

Go to step 7.

Repair harness 
and connector.

NOTE:
In this case, repair
the following:
• Open circuit in 
harness between 
throttle position 
sensor and ECM 
connector
• Poor contact in 
throttle position 
sensor connector
• Poor contact in 
ECM connector
• Poor contact in 
coupling connector
• Poor contact in 
joint connector

7

CHECK HARNESS BETWEEN ECM AND 
THROTTLE POSITION SENSOR CONNEC-
TOR.
1) Turn ignition switch to OFF.
2) Measure resistance of harness between 

ECM connector and throttle position sensor 
connector.

Connector & terminal

(B135) No. 13 — (E13) No. 3:

Is the measured value less than the speci-
fied value?

1 

Ω

Go to step 8.

Repair harness 
and connector.

NOTE:
In this case, repair
the following:
• Open circuit in 
harness between 
throttle position 
sensor and ECM 
connector
• Poor contact in 
ECM connector
• Poor contact in 
throttle position 
sensor connector
• Poor contact in 
coupling connector

8

CHECK HARNESS BETWEEN ECM AND 
THROTTLE POSITION SENSOR CONNEC-
TOR.
Measure resistance of harness between throt-
tle position sensor connector and engine 
ground.

Connector & terminal

(E13) No. 3 — Engine ground:

Does the measured value exceed the specified 
value?

1 M

Ω

Go to step 9.

Repair ground 
short circuit in har-
ness between 
throttle position 
sensor and ECM 
connector.

9

CHECK POOR CONTACT.
Check poor contact in throttle position sensor 
connector. 
Is there poor contact in throttle position sensor 
connector?

There is poor contact.

Repair poor con-
tact in throttle posi-
tion sensor 
connector.

Replace throttle 
position sensor.  
<Ref. to 
FU(H4SO)-30, 
Throttle Position 
Sensor.>

Step

Value

Yes

No

EN(H4SO)-133

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

MEMO:

EN(H4SO)-134

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

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

HIGH INPUT —

• DTC DETECTING CONDITION:

• Immediately at fault recognition

• TROUBLE SYMPTOM:

• Erroneous idling
• Engine stalls.
• Poor driving performance

CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode<Ref. to EN(H4SO)-47, OPER-
ATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4SO)-40, OPERATION, Inspection 
Mode.> .
• WIRING DIAGRAM:

EN-01126

19

13

3

9

11

12

2

3

4

E2

B21

E13

THROTTLE

POSITION

SENSOR

B21

1 2

3 4

5

6 7

8

9 10

11 12

13

14 15

16

17 18

19 20

B135 ECM

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

B135

B83

1 2 3 4 5 6

E13

1 2 3 4

B83

3

1

FG

2

4

EG

: FOR G.C.C COUNTRIES MODEL 

: EXCEPT FOR G.C.C COUNTRIES MODEL 

FG

EG

EN(H4SO)-135

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

Step

Value

Yes

No

1

CHECK CURRENT DATA.
1) Start engine.
2) Read data of throttle position sensor signal 

using Subaru Select Monitor or OBD-II gen-
eral scan tool.
Does the measured value exceed the spec-
ified value?

NOTE:

•Subaru Select Monitor
For detailed operation procedure, refer to the 
“READ CURRENT DATA FOR ENGINE”. 
<Ref. to EN(H4SO)-32, Subaru Select Moni-
tor.>  
•OBD-II general scan tool
For detailed operation procedures, refer to the 
OBD-II General Scan Tool Instruction Manual.

4.9 V

Go to step 2.

Even if MI lights 
up, the circuit has 
returned to a nor-
mal condition at 
this time. A tempo-
rary poor contact 
of the connector 
may be the cause.

NOTE:
In this case, repair
the following:
• Poor contact in 
throttle position 
sensor connector
• Poor contact in 
ECM connector
• Poor contact in 
coupling connector

2

CHECK HARNESS BETWEEN THROTTLE 
POSITION SENSOR AND ECM CONNEC-
TOR.
1) Turn ignition switch to OFF.
2) Disconnect connector from throttle position 

sensor.

3) Measure resistance of harness between 

throttle position sensor connector and 
engine ground.

Connector & terminal

(E13) No. 2 — Engine ground:

Is the measured value less than the speci-
fied value?

5 

Ω

Go to step 3.

Repair harness 
and connector.

NOTE:
In this case, repair
the following:
• Open circuit in 
harness between 
throttle position 
sensor and ECM 
connector
• Poor contact in 
coupling connector
• Poor contact in 
joint connector

3

CHECK HARNESS BETWEEN THROTTLE 
POSITION SENSOR AND ECM CONNEC-
TOR.
1) Turn ignition switch to ON.
2) Measure voltage between throttle position 

sensor connector and engine ground.

Connector & terminal

(E13) No. 3 (+) — Engine ground (

−−−−

):

Does the measured value exceed the spec-
ified value?

4.9 V

Repair battery 
short circuit in har-
ness between 
throttle position 
sensor and ECM 
connector. After 
repair, replace 
ECM. <Ref. to 
FU(H4SO)-45, 
Engine Control 
Module.>

Replace throttle 
position sensor.  
<Ref. to 
FU(H4SO)-30, 
Throttle Position 
Sensor.>