Subaru Legacy III (2000-2003 year). Service manual — part 227

EN(H4SOw/oOBD)-98

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

P: DTC 51 PARK/NEUTRAL POSITION SWITCH (AT VEHICLE)

• DIAGNOSIS:

• The park/neutral position switch signal is abnormal.
• The shift cable is connected abnormally.
• The harness connector between ECM and inhibitor switch is in short or open.

• TROUBLE SYMPTOM:

• Erroneous idling

CAUTION:
After repair or replacement of faulty parts, conduct CLEAR MEMORY and INSPECTION MODES. <Ref.
to EN(H4SOw/oOBD)-28, OPERATION, Clear Memory Mode.> and <Ref. to EN(H4SOw/oOBD)-26, OP-
ERATION, Inspection Mode.>
• WIRING DIAGRAM:

EN-01063

12

INHIBITOR SWITCH

7

P

R

N

D

3

2

1

12

11

T7

T3

B12

B14

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

T7

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

26

B135

ECM

STARTER MOTOR

B12

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

EN(H4SOw/oOBD)-99

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

Step

Value

Yes

No

1

CHECK INPUT SIGNAL FOR ECM.
1) Turn ignition switch to ON.
2) Measure voltage between ECM and chas-

sis ground in selector lever “N” and “P”
positions.

Connector & terminal

(B135) No. 26 (+) — Chassis ground (

−−−−

):

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

1 V

Go to step 2.

Go to step 3.

2

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.

Go to step 3.

3

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

(B135) No. 26 — (T7) No. 12:

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

1

Ω

Go to step 4.

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
(B12)
• Poor contact in
inhibitor switch
connector
• Poor contact in
ECM connector

4

CHECK HARNESS BETWEEN ECM AND
TRANSMISSION HARNESS CONNECTOR.
Measure resistance of harness between ECM
connector and chassis ground.

Connector & terminal

(B135) No. 26 — Chassis ground:

Is the measured value less than the specified
value?

10

Ω

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

Go to step 5.

5

CHECK INHIBITOR SWITCH GROUND LINE.
Remove re-starter motor connector.
Measure resistance of harness between inhibi-
tor switch connector and engine ground.

Connector & terminal

(T7) No. 12 — (B14) No. 1:

Is the measured value less than the specified
value?

5

Ω

Go to step 6.

Repair open circuit
in inhibitor switch
ground line.

6

CHECK STARTER MOTOR.
Check starter motor. <Ref. to SC(H4SO)-10,
INSPECTION, Starter.>

Starter motor is normal.

Go to step 7.

Repair or replace
starter motor.

7

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.

Replace ECM.
<Ref. to
FU(H4SOw/
oOBD)-42, Engine
Control Module.>

EN(H4SOw/oOBD)-100

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

Q: DTC 85 CHARGE SYSTEM

• DIAGNOSIS:

• Power source voltage of the ECM is low or high.

• TROUBLE SYMPTOM:

• Charge warning light comes on.

CAUTION:
After repair or replacement of faulty parts, conduct CLEAR MEMORY and INSPECTION MODES. <Ref.
to EN(H4SOw/oOBD)-28, OPERATION, Clear Memory Mode.> and <Ref. to EN(H4SOw/oOBD)-26, OP-
ERATION, Inspection Mode.>
• WIRING DIAGRAM:

EN-01064

2

1

F44

B61

ECM

B47

B136

3

4

1

2

5

6

B136

F44

B47

SBF-5

SBF-1

BATTERY

MAIN RELAY

1

2

3

5

4

6

6

LHD

LHD

RHD

RHD

GENERATOR

1 2 3 4
5 6 7 8

5

4

6 7

8

2

1

9

3

10

22

23

11 12 13 14 15

24 25

26 27

16 17 18

28 29

19 20

21

30

EN(H4SOw/oOBD)-101

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

Step

Value

Yes

No

1

CHECK GENERATOR.
1) Start engine.
2) Idling after warm-up.
3) Measure voltage between generator B ter-

minal and chassis ground.

Terminal

Generator B terminal (+) — Chassis
ground (–):

Is the measured value within the specified
value?

10.8 V — 16.2 V

Go to step 2.

Repair generator.
<Ref. to
SC(H4SO)-14,
Generator.>

2

CHECK GENERATOR.
1) Run engine at 5,000 rpm.
2) Measure voltage between generator B ter-

minal and chassis ground.

Terminal

Generator B terminal (+) — Chassis
ground (

−−−−

):

Is the measured value within the specified
value?

10.8 V — 16.2 V

Go to step 3.

Repair generator.
<Ref. to
SC(H4SO)-14,
Generator.>

3

CHECK BATTERY TERMINAL.
Turn ignition switch to OFF.
Are the positive and negative battery terminals
tightly clamped?

Battery terminal is tightly
clamped.

Go to step 4.

Tighten the clamp
of terminal.

4

CHECK INPUT VOLTAGE OF ECM.
1) Run the engine at idle.
2) Measure voltage between ECM connector

and chassis ground.

Connector & terminal

(B136) No. 1 (+) — Chassis ground (

−−−−

):

(B136) No. 2 (+) — Chassis ground (

−−−−

):

Is the measured value within the specified
value?

10.8 V — 16.2 V

Go to step 5.

Repair harness
connector
between battery,
main relay and
ECM.

5

CHECK POOR CONTACT IN CONNECTORS.
Is there poor contact in connectors between
generator, battery and ECM?

There is poor contact.

Repair connector.

Go to step 6.

6

CHECK ECM.
1) Connect all connectors.
2) Erase the memory. <Ref. to EN(H4SOw/

oOBD)-28, OPERATION, Clear Memory
Mode.>

3) Perform inspection mode. <Ref. to

EN(H4SOw/oOBD)-26, OPERATION,
Inspection Mode.>

4) Read out the trouble code. <Ref. to

EN(H4SOw/oOBD)-24, OPERATION,
Read Diagnostic Trouble Code (DTC).>
Is the same trouble code (DTC) as in the
current diagnosis still being output?

DTC 85 is displayed.

Replace genera-
tor.

Go to step 7.

7

CHECK ANY OTHER TROUBLE CODES AP-
PEARANCE.
Are other trouble codes (DTC) being output?

DTC is displayed.

Proceed with the
diagnosis corre-
sponding to the
trouble code.

A temporary poor
contact.