Subaru Legacy (2005 year). Service manual — part 340

EN(H4DOTC)(diag)-129

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

Step

Check

Yes

No

1

CHECK HARNESS BETWEEN KNOCK SEN-
SOR AND ECM CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM har-
ness connector and chassis ground.

Connector & terminal

(B136) No. 25 — Chassis ground:

Is the resistance more than
700 k

Ω?

Go to step 2.

Repair the har-
ness and connec-
tor.

NOTE:
In this case, repair
the following:
• Open circuit of
harness between
knock sensor and
ECM connector
• Poor contact in
knock sensor con-
nector
• Poor contact in
coupling connector

2

CHECK KNOCK SENSOR.
1) Disconnect the connector from knock sen-
sor.
2) Measure the resistance between knock
sensor connector terminal and engine ground.

Terminals

No. 2 — Engine ground:

Is the resistance more than
700 k

Ω?

Go to step 3.

Repair the har-
ness and connec-
tor.

NOTE:
In this case, repair
the following:
• Poor contact in
knock sensor con-
nector
• Poor contact in
coupling connector

3

CHECK INSTALLATION CONDITION OF
KNOCK SENSOR.

Is the knock sensor installation
bolt tightened securely?

Replace the knock
sensor. <Ref. to
FU(H4DOTC)-25,
Knock Sensor.>

Tighten the knock
sensor installation
bolt securely.

EN(H4DOTC)(diag)-130

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AF:DTC P0328 KNOCK SENSOR 1 CIRCUIT HIGH (BANK 1 OR SINGLE SEN-

SOR)

DTC DETECTING CONDITION:
Immediately at fault recognition
TROUBLE SYMPTOM:
• Poor driving performance
• Knocking occurs.

CAUTION:
After repair or replacement of faulty parts, perform Clear Memory Mode <Ref. to EN(H4DOTC)(diag)-
37, OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4DOTC)(diag)-30, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:

EN-01953

E1

E14

B20

2

13

B136

ECM

33

25

E

E14

1 2

B20

KNOCK
SENSOR

B136

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

35

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

13 14 15 16

EN(H4DOTC)(diag)-131

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

Step

Check

Yes

No

1

CHECK HARNESS BETWEEN KNOCK SEN-
SOR AND ECM CONNECTOR.
Measure the resistance of harness between
ECM connector and chassis ground.

Connector & terminal

(B136) No. 25 — Chassis ground:

Is the resistance less than 400
k

Ω?

Go to step 2.

Go to step 3.

2

CHECK KNOCK SENSOR.
1) Disconnect the connector from knock sen-
sor.
2) Measure the resistance between knock
sensor connector terminal and engine ground.

Terminals

No. 2 — Engine ground:

Is the resistance less than 400
k

Ω?

Replace the knock
sensor. <Ref. to
FU(H4DOTC)-25,
Knock Sensor.>

Repair the ground
short circuit of har-
ness between
knock sensor con-
nector and ECM
connector.

NOTE:
The harness be-
tween both con-
nectors are
shielded. Repair
the short circuit of
harness covered
with shield.

3

CHECK INPUT SIGNAL OF ECM.
1) Connect the connectors to ECM and knock
sensor.
2) Turn the ignition switch to ON.
3) Measure the voltage between ECM and
chassis ground.

Connector & terminal

(B136) No. 25 (+) — Chassis ground (

−

):

Is the voltage more than 2 V?

Even if the mal-
function indicator
light illuminates,
the circuit has
returned to a nor-
mal condition at
this time. (How-
ever, the possibility
of poor contact still
remains.)

NOTE:
In this case, repair
the following:
• Poor contact in
knock sensor con-
nector
• Poor contact in
ECM connector
• Poor contact in
coupling connector

Repair the poor
contact in ECM
connector.

EN(H4DOTC)(diag)-132

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

AG:DTC P0335 CRANKSHAFT POSITION SENSOR “A” CIRCUIT

DTC DETECTING CONDITION:
Immediately at fault recognition
TROUBLE SYMPTOM:
• Engine stalls.
• Failure of engine to start

CAUTION:
After repair or replacement of faulty parts, perform Clear Memory Mode <Ref. to EN(H4DOTC)(diag)-
37, OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4DOTC)(diag)-30, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:

EN-01954

E1

E10

B20

2

1

8

7

B135 ECM

22

31

10

E

E10

1 2

B20

CRANKSHAFT
POSITION
SENSOR

B135

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

29 30 31

32 33

34 35

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

13 14 15 16