Subaru Legacy III (2000-2003 year). Manual — part 213

EN(H4SOw/oOBD)-42

ENGINE (DIAGNOSTICS)

DIAGNOSTICS FOR ENGINE STARTING FAILURE

7

CHECK HARNESS BETWEEN BATTERY
AND IGNITION SWITCH CONNECTOR.
1) Ignition switch to OFF.
2) Disconnect connector from ignition switch.
3) Measure power supply voltage between

ignition switch connector and chassis
ground.

Connector & terminal

(B72) No. 1 (+) — Chassis ground (

−−−−

):

Does the measured value exceed the spec-
ified value?

10 V

Go to step 8.

Repair open circuit
in harness
between ignition
switch and battery.

8

CHECK HARNESS BETWEEN BATTERY
AND IGNITION SWITCH CONNECTOR.
1) Connect connector to ignition switch.
2) Turn ignition switch to START.
3) Measure voltage between ignition switch

and chassis ground.

Connector & terminal

(B72) No. 3 (+) — Chassis ground (

−−−−

):

Does the measured value exceed the spec-
ified value?

10 V

Go to step 9.

Replace ignition
switch.

9

CHECK TRANSMISSION TYPE.
Is the vehicle AT?

Vehicle is AT.

Go to step 10.

Repair open circuit
between ignition
switch and starter
motor circuit.

10

CHECK INHIBITOR SWITCH CIRCUIT.
1) Turn ignition switch to OFF.
2) Place the selector lever in the “P” or “N”

position.

3) Separate transmission harness connector.
4) Measure resistance between transmission

harness connector receptacle's terminals.

Connector & terminal

(T3) No. 11 — No. 12:

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

1

Ω

Repair open circuit
in harness
between starter
motor and ignition
switch connector.

Go to step 11.

11

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

transmission harness and inhibitor switch
connector.

Connector & terminal

(T3) No. 11 — (T7) No. 7:
(T3) No. 12 — (T7) No. 12:

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

1

Ω

Go to step 12.

Repair open circuit
in harness
between transmis-
sion harness and
inhibitor switch
connector.

12

CHECK POOR CONTACT.
Check poor contact in inhibitor switch connec-
tor.
Is there poor contact in inhibitor switch connec-
tor?

There is poor contact.

Repair poor con-
tact in inhibitor
switch connector.

Replace inhibitor
switch.

Step

Value

Yes

No

EN(H4SOw/oOBD)-43

ENGINE (DIAGNOSTICS)

DIAGNOSTICS FOR ENGINE STARTING FAILURE

C: CONTROL MODULE POWER SUPPLY AND GROUND LINE

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-01046

C9

B7

C1

B19

C2

E3

B22

A8

A7

A27

C22

C21

B6

B25

13

15

14

16

B47

BATTERY

MAIN RELAY

1

2

3

5

4

6

F44

B61

SBF-5

6

LHD

RHD

RHD

SBF-4

SBF-1

4

1

B72

IGNITION
SWITCH

ECM

B134

A :

B135

B :

B136

C :

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

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

B135

B136

C:

B:

A: B134

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

B47

3

4

1

2

5

6

B72

3 4

1 2

B22

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

13 14 15 16

NO. 11

1 2 3 4
5 6 7 8

F44

LHD

MT

EN(H4SOw/oOBD)-44

ENGINE (DIAGNOSTICS)

DIAGNOSTICS FOR ENGINE STARTING FAILURE

Step

Value

Yes

No

1

CHECK MAIN RELAY.
1) Turn the ignition switch to OFF.
2) Remove main relay.
3) Connect battery to main relay terminals No.

1 and No. 2.

4) Measure resistance between main relay

terminals.

Terminals

No. 3 — No. 5:
No. 4 — No. 6:

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

10

Ω

Go to step 2.

Replace main
relay.

2

CHECK GROUND CIRCUIT OF ECM.
1) Disconnect connector from ECM.
2) Measure resistance of harness between

ECM and chassis ground.

Connector & terminal

(B136) No. 21 — Chassis ground:
(B136) No. 22 — Chassis ground:
(B135) No. 6 — Chassis ground (only
LHD model):
(B135) No. 25 — Chassis ground (only
MT model):
(B134) No. 27 — Chassis ground:
(B134) No. 8 — Chassis ground:
(B134) No. 7 — Chassis ground:

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

5

Ω

Go to step 3.

Repair open circuit
in harness
between ECM
connector and
engine grounding
terminal.

3

CHECK INPUT VOLTAGE OF ECM.
Measure voltage between ECM connector and
chassis ground.

Connector & terminal

(B136) No. 9 (+) — Chassis ground (–):

Does the measured value exceed the specified
value?

10 V

Go to step 4.

Repair open or
ground short cir-
cuit of power sup-
ply circuit.

4

CHECK INPUT VOLTAGE OF ECM.
1) Turn ignition switch to ON.
2) Measure voltage between ECM connector

and chassis ground.

Connector & terminal

(B135) No. 7 (+) — Chassis ground (–):

Does the measured value exceed the spec-
ified value?

10 V

Go to step 5.

Repair open or
ground short cir-
cuit of power sup-
ply circuit.

5

CHECK HARNESS BETWEEN ECM AND
MAIN RELAY CONNECTOR.
1) Turn ignition switch to OFF.
2) Measure resistance between ECM and

chassis ground.

Connector & terminal

(B135) No. 19 — Chassis ground:

Does the measured value exceed the spec-
ified value?

1 M

Ω

Go to step 6.

Repair ground
short circuit in har-
ness between
ECM connector
and main relay
connector, then
replace ECM.

EN(H4SOw/oOBD)-45

ENGINE (DIAGNOSTICS)

DIAGNOSTICS FOR ENGINE STARTING FAILURE

6

CHECK OUTPUT VOLTAGE FROM ECM.
1) Connect connector to ECM.
2) Turn ignition switch to ON.
3) Measure voltage between ECM connector

and chassis ground.

Connector & terminal

(B135) No. 19 (+) — Chassis ground (–):

Does the measured value exceed the spec-
ified value?

10 V

Go to step 7.

Replace ECM.

7

CHECK INPUT VOLTAGE OF MAIN RELAY.
Check voltage between main relay connector
and chassis ground.

Connector & terminal

(B47) No. 2 (+) — Chassis ground (–):

Does the measured value exceed the specified
value?

10 V

Go to step 8.

Repair open circuit
in harness
between ECM
connector and
main relay con-
nector.

8

CHECK GROUND CIRCUIT OF MAIN RE-
LAY.
1) Turn ignition switch to OFF.
2) Measure resistance between main relay

connector and chassis ground.

Connector & terminal

(B47) No. 1 — Chassis ground:

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

5

Ω

Go to step 9.

Repair open circuit
between main
relay and chassis
ground.

9

CHECK INPUT VOLTAGE OF MAIN RELAY.
Measure voltage between main relay connec-
tor and chassis ground.

Connector & terminal

(B47) No. 5 (+) — Chassis ground (

−−−−

):

(B47) No. 6 (+) — Chassis ground (

−−−−

):

Does the measured value exceed the specified
value?

10 V

Go to step 10.

Repair open or
ground short cir-
cuit in harness of
power supply cir-
cuit.

10

CHECK INPUT VOLTAGE OF ECM.
1) Connect main relay connector.
2) Turn ignition switch to ON.
3) Measure voltage between ECM connector

and chassis ground.

Connector & terminal

(B136) No. 1 (+) — Chassis ground (–):
(B136) No. 2 (+) — Chassis ground (–):

Does the measured value exceed the spec-
ified value?

10 V

Check ignition
control system.
<Ref. to
EN(H4SOw/
oOBD)-46, IGNI-
TION CONTROL
SYSTEM, Diag-
nostics for Engine
Starting Failure.>

Repair open or
ground short cir-
cuit in harness
between ECM
connector and
main relay con-
nector.

Step

Value

Yes

No