Subaru Legacy III (2000-2003 year). Service manual — part 373

EN(H6DO)-294

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

CB:DTC P0851 — NEUTRAL SWITCH INPUT CIRCUIT LOW —

• DTC DETECTING CONDITION:

• Two consecutive driving cycles with fault

• TROUBLE SYMPTOM:

• Erroneous idling

CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H6DO)-54, OP-
ERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H6DO)-47, OPERATION, Inspec-
tion Mode.>.
• WIRING DIAGRAM:

EN-00834

12

INHIBITOR SWITCH

7

P

R

N

D

3

2

1

12

11

T7

T3

B12

B14

B134

T7

1 2 3 4 5 6
7 8 9 10 11 12

8

B134

ECM

STARTER MOTOR

1 2 3 4

10 11 12

19 20 21

13

5

6

14 15

7

8 9

16 17

18

22

B12

1 2 3 4
5 6 7 8
9 10 11 12

EN(H6DO)-295

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

Step

Value

Yes

No

1

CHECK ANY OTHER DTC ON DISPLAY.
Is any other DTC displayed?

Another DTC is displayed.

Inspect the rele-
vant DTC using
“List of Diagnostic
Trouble Code
(DTC)”. <Ref. to
EN(H6DO)-89, List
of Diagnostic
Trouble Code
(DTC).>

Go to step 2.

2

CHECK INPUT SIGNAL FOR ECM.
1) Turn ignition switch to ON.
2) Move select lever to any position except for

“N” and “P”.

3) Measure voltage between ECM and chas-

sis ground.

Connector & terminal

(B134) No. 8 (+) — Chassis ground (

−−−−

):

Is the measured value within the specified
range?

4.5 — 5.5 V

Even if MI lights
up, the circuit has
returned to a nor-
mal condition at
this time.

Go to step 3.

3

CHECK HARNESS BETWEEN ECM AND
TRANSMISSION HARNESS CONNECTOR.
1) Turn ignition switch to OFF.
2) Disconnect connectors from ECM and

transmission harness connector (T3).

3) Measure resistance of harness between

ECM connector and chassis ground.

Connector & terminal

(B134) No. 8 — Chassis ground:

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

10

Ω

Repair ground
short circuit in har-
ness between
ECM and trans-
mission harness
connector.

Go to step 4.

4

CHECK TRANSMISSION HARNESS CON-
NECTOR.
1) Disconnect connector from inhibitor switch.
2) Measure resistance of harness between

transmission harness connector and
engine ground.

Connector & terminal

(T3) No. 12 — Engine ground:

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

10

Ω

Repair ground
short circuit in har-
ness between
transmission har-
ness and inhibitor
switch connector.

Go to step 5.

5

CHECK INHIBITOR SWITCH.
By moving select lever any position except for
“N” and “P”, measure resistance between
inhibitor switch connector socket terminals.

Terminals

No. 7 — No. 12:

Does the measured value exceed the specified
value?

1 M

Ω

Go to step 6.

Replace inhibitor
switch. <Ref. to
AT-49, Inhibitor
Switch.>

6

CHECK SELECTOR CABLE CONNECTION.
Is there any fault in selector cable connection
to inhibitor switch?

There is a malfunction.

Repair selector
cable connection.
<Ref. to CS-12,
Select Cable.>

Contact SUBARU
distributor service.

NOTE:
Inspection by DTM
is required, be-
cause probable
cause is deteriora-
tion of multiple
parts.

EN(H6DO)-296

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

CC:DTC P0852 — NEUTRAL SWITCH INPUT CIRCUIT HIGH —

• DTC DETECTING CONDITION:

• Two consecutive driving cycles with fault

• TROUBLE SYMPTOM:

• Erroneous idling

CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H6DO)-54, OP-
ERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H6DO)-47, OPERATION, Inspec-
tion Mode.>.
• WIRING DIAGRAM:

EN-00834

12

INHIBITOR SWITCH

7

P

R

N

D

3

2

1

12

11

T7

T3

B12

B14

B134

T7

1 2 3 4 5 6
7 8 9 10 11 12

8

B134

ECM

STARTER MOTOR

1 2 3 4

10 11 12

19 20 21

13

5

6

14 15

7

8 9

16 17

18

22

B12

1 2 3 4
5 6 7 8
9 10 11 12

EN(H6DO)-297

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

Step

Value

Yes

No

1

CHECK ANY OTHER DTC ON DISPLAY.
Is any other DTC displayed?

Another DTC is displayed.

Inspect the rele-
vant DTC using
“List of Diagnostic
Trouble Code
(DTC)”. <Ref. to
EN(H6DO)-89, List
of Diagnostic
Trouble Code
(DTC).>

Go to step 2.

2

CHECK INPUT SIGNAL FOR ECM.
1) Turn ignition switch to ON.
2) Move select lever to “N” and “P” positions.
3) Measure voltage between ECM and chas-

sis ground.

Connector & terminal

(B134) No. 8 (+) — Chassis ground (

−−−−

):

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

1 V

Go to step 3.

Go to step 5.

3

CHECK INPUT SIGNAL FOR ECM.
By moving select lever to any position except
for “N” and “P”, measure ECM and chassis
ground.

Connector & terminal

(B134) No. 8 (+) — Chassis ground (

−−−−

):

Is the measured value within the specified
range?

4.5 — 5.5 V

Go to step 4.

Go to step 5.

4

CHECK POOR CONTACT.
Check poor contact in ECM connector.
Is there poor contact in ECM connector?

There is poor contact.

Repair poor con-
tact in ECM con-
nector.

Contact SUBARU
distributor service.

NOTE:
Inspection by DTM
is required, be-
cause probable
cause is deteriora-
tion of multiple
parts.

5

CHECK INPUT SIGNAL FOR ECM.
Measure voltage between ECM and chassis
ground.

Connector & terminal

(B134) No. 8 (+) — Chassis ground (

−−−−

):

Does the measured value exceed the specified
value?

10 V

Repair battery
short circuit in har-
ness between
ECM and inhibitor
switch connector.

Go to step 6.

6

CHECK HARNESS BETWEEN ECM AND IN-
HIBITOR SWITCH CONNECTOR.
1) Turn ignition switch to OFF.
2) Disconnect connectors from ECM and

inhibitor switch.

3) Measure resistance of harness between

ECM and inhibitor switch connector.

Connector & terminal

(B134) No. 8 — (T7) No. 12:

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

1

Ω

Go to step 7.

Repair harness
and connector.

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