Subaru Legacy IV (2008 year). Manual - part 159

EN(H4SO)(diag)-239

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

CG:DTC P0852 NEUTRAL SWITCH INPUT CIRCUIT HIGH (MT MODEL)

DTC DETECTING CONDITION:
• Two consecutive driving cycles with fault
• GENERAL DESCRIPTION <Ref. to GD(H4SO)-155, DTC P0852 NEUTRAL SWITCH INPUT CIRCUIT
HIGH (MT MODEL), Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling

CAUTION:
After repair or replacement of faulty parts, perform Clear Memory Mode <Ref. to EN(H4SO)(diag)-50,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(H4SO)(diag)-41, PROCEDURE,
Inspection Mode.>.
WIRING DIAGRAM:

EN-06642

B12

T3

B14

T7

INHIBITOR

SWITCH

NEUTRAL
POSITION

SWITCH

STARTER MOTOR

(MAGNET)

P

R

N

D

6

9

12

11

B136

ECM

31

6

B12

B25

T7

1 2 3 4
5 6 7 8
9 10 11 12

B136

1

B25

T2

T2

B25

2

MT

AT

AT

AT

MT

MT

M

2

1

C:

C:

B122

*

*

: TERMINAL No. OPTIONAL ARRANGEMENT

*

16

10 11 12 13 14 15

25

24

30

9

8

7

17 18 19 20
28

21 22 23

29

32

31

1

2

3

4

5

6

27

26

33 34 35

B122

3 4

5 6

1 2

7 8

TO STARTER RELAY

1 2 3 4 5

7

6

9

8

EN(H4SO)(diag)-240

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

Step

Check

Yes

No

1

CHECK INPUT SIGNAL OF ECM.
1) Turn the ignition switch to ON.
2) Place the shift lever in neutral.
3) Measure the voltage between ECM and 
chassis ground.

Connector & terminal

(B136) No. 31 (+) — Chassis ground (–):

Is the voltage less than 1 V?

Repair the poor 
contact of ECM 
connector.

Go to step 2.

2

CHECK HARNESS BETWEEN ECM AND 
NEUTRAL POSITION SWITCH CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect connectors from the ECM and 
transmission harness.
3) Measure the resistance of harness between 
ECM and transmission harness connector.

Connector & terminal

(B136) No. 31 — (T2) No. 2:

Is the resistance less than 1 

:? Go to step 3.

Repair the open 
circuit in harness 
between ECM and 
transmission har-
ness connector.

3

CHECK HARNESS BETWEEN ECM AND 
NEUTRAL POSITION SWITCH CONNEC-
TOR.
Measure the resistance of harness between 
ECM and transmission harness connector.

Connector & terminal

(B136) No. 6 — (T2) No. 1:

Is the resistance less than 5 

:? Go to step 4.

Repair the harness 
and connector.

NOTE:
In this case, repair
the following item:
• Open circuit of
harness between
transmission har-
ness connector
and engine ground
• Poor contact of
coupling connector

4

CHECK NEUTRAL POSITION SWITCH.
1) Place the shift lever in neutral.
2) Measure the resistance between transmis-
sion harness connector terminals.

Connector & terminal

(T2) No. 1 — No. 2:

Is the resistance less than 1 

:? Repair the poor 

contact of trans-
mission harness 
connector.

Repair the open 
circuit of transmis-
sion harness or 
replace the neutral 
position switch. 
<Ref. to 5MT-35, 
Switches and Har-
ness.>

EN(H4SO)(diag)-241

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

CH:DTC P1152 O2 SENSOR CIRCUIT RANGE/PERFORMANCE (LOW) (BANK1 

SENSOR1)

DTC DETECTING CONDITION:
• Two consecutive driving cycles with fault
• GENERAL DESCRIPTION <Ref. to GD(H4SO)-156, DTC P1152 O2 SENSOR CIRCUIT RANGE/PER-
FORMANCE (LOW) (BANK1 SENSOR1), Diagnostic Trouble Code (DTC) Detecting Criteria.>

CAUTION:
After repair or replacement of faulty parts, perform Clear Memory Mode <Ref. to EN(H4SO)(diag)-50,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(H4SO)(diag)-41, PROCEDURE,
Inspection Mode.>.
WIRING DIAGRAM:

EN-06835

B137

8

5

6

10 11 12 13 14 15

7

2

1

3

4

16

30

19 20

22
28 29

9

17

18

25

21

23

24

31

26 27

3

4

1

2

5

6

B327

SBF-5

E

E

E

B327

E22

6

4

5

3

2
1

6

4

1

3

B1

B9

B8

C3

C2

A5

D7

D1

D2

D3

36

52

34

35

37

B134

A:

B135

B:

B136

C:

B137

D:

B21

E2

ECM

B21

E2

50

51

3

4

E2

B21

E

E22

B138

B134

B135

A:

B:

B136

C:

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

33 34

29

32

30 31

BATTERY

FRONT OXYGEN 

(A/F) SENSOR

A/F, OXYGEN 
SENSOR RELAY

B138

*

*

 : TERMINAL No. OPTIONAL  
 ARRANGEMENT

*

3

1

6 5 4

2

5

6

7

2

1

3

4

29

10 11 12 13 14 15

25

24

16

30

9

8

17 18 19

20
28

21 22 23

32

31

26 27

33

34 35

16

10 11 12 13 14 15

25

24

30

9

8

7

17 18 19 20
28

21 22 23

29

32

31

1

2

3

4

5

6

27

26

33 34 35

3 4

5 6

1 2

7 8

B21

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 26 27 28 29 30 31 32 33

34

35

42

43

36

37

38

39

48

49

50

51

52

53

54

40

41

44

45

46

47

EN(H4SO)(diag)-242

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

Step

Check

Yes

No

1

CHECK FRONT OXYGEN (A/F) SENSOR 
CONNECTOR AND COUPLING CONNEC-
TOR.

Has water entered the connec-
tor?

Completely 
remove any water 
inside.

Go to step 2.

2

CHECK HARNESS BETWEEN ECM AND 
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and 
front oxygen (A/F) sensor.
3) Measure the resistance of harness between 
ECM and front oxygen (A/F) sensor connector.

Connector & terminal

(B135) No. 9 — (E22) No. 1:
(B135) No. 8 — (E22) No. 3:

Is the resistance less than 1 

:? Go to step 3.

Repair the harness 
and connector.

NOTE:
In this case, repair
the following item:
• Open circuit in
harness between
ECM and front oxy-
gen (A/F) sensor
connector
• Poor contact of
coupling connector

3

CHECK POOR CONTACT.
Check for poor contact in the front oxygen (A/F) 
sensor connector.

Is there poor contact in front 
oxygen (A/F) sensor connec-
tor?

Repair the poor 
contact of the front 
oxygen (A/F) sen-
sor connector.

Replace the front 
oxygen (A/F) sen-
sor. <Ref. to 
FU(H4SO)-35,
Front Oxygen (A/F) 
Sensor.>