Subaru Legacy IV (2008 year). Service manual - part 1178

LAN(diag)-46

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

LAN SYSTEM (DIAGNOSTICS)

Step

Check

Yes

No

1

CHECK HARNESS.
1) Disconnect the body integrated unit connec-
tor (B280).
2) Measure the resistance between body inte-
grated unit connector and chassis ground.

Connector & terminal

(B280) No. 6 — Chassis ground:

Is the resistance between 20 — 
30 

:?

Go to step 5.

Go to step 2.

2

CHECK HARNESS.
1) Disconnect the body integrated unit connec-
tor (B280).
2) Disconnect the shift lock solenoid connec-
tor.
3) Measure the resistance between body inte-
grated unit connector and shift lock solenoid 
connector.

Connector & terminal

(B280) No. 6 — (B116) No. 3:

Is the resistance less than 10 

:? Go to step 3.

Repair or replace 
the open or short 
circuit of harness.

3

CHECK SHIFT LOCK SOLENOID.
1) Disconnect the shift lock solenoid connec-
tor.
2) Measure the internal resistance of shift lock 
solenoid.

Connector & terminal

(B116) No. 3 — No. 4:

Is the resistance between 20 — 
30 

:?

Go to step 4.

Replace the shift 
lock solenoid.

4

CHECK GROUND CIRCUIT.
1) Disconnect the shift lock solenoid connec-
tor.
2) Measure the resistance between the shift 
lock solenoid connector and chassis ground.

Connector & terminal

(B116) No. 4 — Chassis ground:

Is the resistance less than 10 

:? Temporary poor 

contact occurs. 
Check the connec-
tion of each termi-
nal and repair 
when necessary.

Replace the body 
integrated unit. 
<Ref. to SL-56, 
Body Integrated 
Unit.>

5

CHECK HARNESS.
1) Disconnect the body integrated unit connec-
tor (B280) and shift lock solenoid connector 
(B116).
2) Measure the resistance between body inte-
grated unit connector (B280) and chassis 
ground.

Connector & terminal

(B280) No. 6 — Chassis ground:

Is the resistance 1 M

: or 

more?

Replace the body 
integrated unit. 
<Ref. to SL-56, 
Body Integrated 
Unit.>

Repair the short 
circuit of harness 
or replace har-
ness.

LAN(diag)-47

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

LAN SYSTEM (DIAGNOSTICS)

H: DTC U1201 CAN-HS COUNTER ABNORMAL

DTC DETECTING CONDITION:
High speed CAN communication of body integrated unit which monitor the error data and non-received data
are faulty.
TROUBLE SYMPTOM:
• “Er HC” is displayed in odo/trip meter. (Except for meter with MID)
• Malfunction indicator light illuminates.
WIRING DIAGRAM:

LAN00382

B40

1 2 3 4 5 6 7 8

9 10 11 12 13 14 15 16

B280

B:

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

B231

1 2 3 4

A: B54

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

B310

4 5 6 7 8 9

26 27 28 29 30

2 3

1

31 32 33 34 35 36

10 11

14 15 16 17 18 19

37 38 39 40

12 13

41 42 43 44 45 46

20 21

23

24

22

25

B230

1

2

3

4

B170

3 4

5 6

1 2

7 8

1 2 3 4 5 6 7 8 9 10

11 12 13 14 15 16 17 18 19 20

B365

B301

4 5 6 7 8 9

16 17 18 19 20

2 3

1

21 22 23 24 25 26

10 11

13

14

12

15

C: B136

B:

B55

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

2

3

B230

YAW RATE 

SENSOR

B231

2

1

STEERING

ANGLE

SENSOR

VDCCM & H/U

B310

35

10

ECM

B136

27

35

B30

B20

BODY 

INTEGRATED UNIT

B280

B:

6

14

B170

B365

B40

CAN JOINT 
CONNEC-
TOR

CAN JOINT 
CONNECTOR

DATA LINK 

CONNECTOR

2

*

1

*

2

*

1

*

3

*

4

*

2

*

1

*

2

*

1

*

2

*

1

*

2

*

1

*

3

*

4

*

3

*

4

*

VDC

VDC

VDC

VDC

ABS

ABS

ABS

ABS

ABSCM & H/U

B301

26

11

VDC

ABS

ABS

TCM

B54

A:

4AT MODEL

5AT MODEL

B21

B20

A18

A17

B55

B:

VDC

*

1

*

2

*

3

*

4

: WITHOUT VDC

ABS

VDC

: TERMINAL No. OPTIONAL ARRANGEMENT 
  AMONG 1, 2, 3, 11, 12 AND 13
: TERMINAL No. OPTIONAL ARRANGEMENT 
  AMONG 8, 9, 10, 18, 19 AND 20
: TERMINAL No. OPTIONAL ARRANGEMENT 
  AMONG 1, 2, 5 AND 6
: TERMINAL No. OPTIONAL ARRANGEMENT 
  AMONG 3, 4, 7 AND 8

: WITH VDC

LAN(diag)-48

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

LAN SYSTEM (DIAGNOSTICS)

Step

Check

Yes

No

1

CHECK DTC.
Connect the Subaru Select Monitor and read all 
DTCs.

Is there any DTC other than for 
the body integrated unit?

Perform the diag-
nosis according to 
the DTC of other 
control modules.

Go to step 2.

2

CHECK DTC.
Check the DTC displayed in the body integrated 
unit.

Is the DTC displayed a current 
malfunction?

Check the connec-
tion of harness 
connectors. Go to 
step 3.

Go to step 4.

3

CHECK DTC.
Turn the ignition switch to OFF and read DTCs 
again.

Is the DTC displayed a current 
malfunction?

Go to step 5.

Go to step 4.

4

CHECK CURRENT DATA.
Using the Subaru Select Monitor, display 
engine speed and vehicle speed signal from 
ECM, TCM, VDC/ABS and body integrated unit 
under the same conditions and compare data.

Do all data values match?

Temporary poor 
contact occurs. 
Perform the Clear 
Memory operation.

Go to step 5.

5

CHECK HARNESS.
1) Disconnect the body integrated unit connec-
tor (B280).
2) Connect the tester to vehicle side connec-
tor, and measure the resistance.

Connector & terminal

(B280) No. 20 — No. 30:

Is the resistance between 55 — 
65 

:?

Go to step 6.

Go to step 9.

6

CHECK HARNESS.
1) Disconnect the TCM connector (B54).
2) Connect the tester to vehicle side connec-
tor, and measure the resistance.

Connector & terminal

5AT model:

(B54) No. 20 — No. 21:

4AT model:

(B54) No. 17 — No. 18:

Is the resistance between 55 — 
65 

:?

Go to step 7.

Go to step 9.

7

CHECK HARNESS.

NOTE:
For ABS model, Go to step 12.
1) Disconnect the yaw rate sensor connector 
(B230).
2) Connect the tester to vehicle side connec-
tor, and measure the resistance.

Connector & terminal

(B230) No. 2 — No. 3:

Is the resistance between 55 — 
65 

:?

Go to step 8.

Go to step 9.

8

CHECK HARNESS.
1) Disconnect the steering angle sensor con-
nector (B231).
2) Connect the tester to vehicle side connec-
tor, and measure the resistance.

Connector & terminal

(B231) No. 1 — No. 2:

Is the resistance between 55 — 
65 

:?

Go to step 12.

Go to step 9.

9

CHECK HARNESS.

Is the measured resistance 
115 — 125 

: when connecting 

the tester to vehicle side con-
nector?

Go to step 12.

Go to step 10.

10

CHECK HARNESS.

Is the measured resistance less 
than 10 

: when connecting the 

tester to vehicle side connec-
tor?

Repair or replace 
the short circuit of 
measured related 
harness.

Go to step 11.

LAN(diag)-49

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

LAN SYSTEM (DIAGNOSTICS)

11

CHECK HARNESS.

Is the measured resistance 
30 M

: or more when connect-

ing the tester to vehicle side 
connector?

Repair or replace 
the open circuit of 
measured related 
harness.

Go to step 12.

12

CHECK HARNESS.
1) Disconnect the VDC/ABS CM connector.
2) Connect the tester to vehicle side harness, 
and measure the resistance.

Connector & terminal

Model with VDC:

(B310) No. 10 — No. 35:

Model without VDC:

(B301) No. 11 — No. 26:

Is the resistance between 115 — 
125 

:?

Go to step 13.

Go to step 14.

13

CHECK CONTROL MODULE.
1) Connect the VDC/ABS CM connector.
2) Disconnect the connector from ECM.
3) Connect the tester to vehicle side harness, 
and measure the resistance between terminals.

Connector & terminal

(B136) No. 27 — No. 35:

Is the resistance between 115 — 
125 

:?

Go to step 16.

Replace the VDC/
ABS CM. <Ref. to 
VDC-7, VDC Con-
trol Module and 
Hydraulic Control 
Unit (VDCCM&H/
U).>

14

CHECK HARNESS.
1) Connect the VDC/ABS CM connector.
2) Disconnect the connector from ECM.
3) Connect the tester to vehicle side harness, 
and measure the resistance between terminals.

Connector & terminal

(B136) No. 27 — No. 35:

Is the resistance between 115 — 
125 

:?

Go to step 15.

Repair or replace 
the open circuit of 
main wiring har-
ness.

15

CHECK CONTROL MODULE.
Connect the tester to ECM terminal, and mea-
sure the resistance.

Connector & terminal

(B136) No. 27 — No. 35:

Is the resistance between 115 — 
125 

:?

Go to step 16.

Replace the ECM. 
<Ref. to 
FU(H6DO)-38, 
Engine Control 
Module (ECM).>

16

CHECK CONTROL MODULE.
1) Connect all the control module connectors.
2) Connect the Subaru Select Monitor and per-
form the clear memory.
3) Disconnect the TCM connector (B54 or 
B55).
4) Turn the ignition switch to ON and read the 
DTC of body integrated unit. <Ref. to 
LAN(diag)-12, READ DIAGNOSTIC TROUBLE 
CODE (DTC), OPERATION, Subaru Select 
Monitor.>

Is DTC U1201 displayed?

Go to step 17.

Check the TCM. 
<Ref. to 5AT(diag)-
18, READ DIAG-
NOSTIC TROU-
BLE CODE (DTC), 
OPERATION, Sub-
aru Select Moni-
tor.>

17

CHECK CONTROL MODULE.
1) Connect the TCM control module connec-
tor.
2) Using the Subaru Select Monitor, perform 
the clear memory.
3) Disconnect the steering angle sensor con-
nector (B231).
4) Turn the ignition switch to ON and read the 
DTC of the body integrated unit. <Ref. to 
LAN(diag)-12, READ DIAGNOSTIC TROUBLE 
CODE (DTC), OPERATION, Subaru Select 
Monitor.>

Is DTC U1201 displayed?

Go to step 18.

Check the steering 
angle sensor. 
<Ref. to 
VDC(diag)-14, 
HOW TO USE 
SUBARU SELECT 
MONITOR, OPER-
ATION, Subaru 
Select Monitor.>

Step

Check

Yes

No