Subaru Legacy IV (2008 year). Manual - part 1179

LAN(diag)-50

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

LAN SYSTEM (DIAGNOSTICS)

18

CHECK CONTROL MODULE.
1) Connect the steering angle sensor connec-
tor.
2) Using the Subaru Select Monitor, perform 
the clear memory.
3) Disconnect the yaw rate sensor connector 
(B230).
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 19.

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

19

CHECK CONTROL MODULE.
1) Connect all the control module connectors.
2) Check the data of “Body Int. Unit Data” on 
the current data display of ECM using Subaru 
Select Monitor.

Is the “ON” displayed?

Go to step 20.

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

20

CHECK CONTROL MODULE.
Check the data of “Body Int. Unit Count” on the 
data display of ECM.

Is the “ON” displayed?

Inspect the ABS/
VDC CM and 
ECM. <Ref. to 
ABS(diag)-13, 
HOW TO USE 
SUBARU SELECT 
MONITOR, OPER-
ATION, Subaru 
Select Monitor.> 
<Ref. to 
VDC(diag)-14, 
HOW TO USE 
SUBARU SELECT 
MONITOR, OPER-
ATION, Subaru 
Select Monitor.> 
<Ref. to 
EN(H6DO)(diag)-
43, SUBARU 
SELECT MONI-
TOR (NORMAL 
MODE), OPERA-
TION, Read Diag-
nostic Trouble 
Code (DTC).>

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

Step

Check

Yes

No

LAN(diag)-51

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

LAN SYSTEM (DIAGNOSTICS)

I:

DTC U1202 CAN-HS BUS OFF

DTC DETECTING CONDITION:
• Find the unit or CAN line in which trouble occurs, and repair and replace it.
• Not received data and error data may be detected at the same time.
TROUBLE SYMPTOM:
“Er HC” is displayed in odo/trip meter. (Except for meter with MID)
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)-52

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

LAN SYSTEM (DIAGNOSTICS)

Step

Check

Yes

No

1

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 2.

Go to step 2.

2

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

Is the DTC displayed a current 
malfunction?

Check the connec-
tion of harness 
connectors. Go to 
step 4.

Go to step 3.

3

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 4.

4

CHECK TCM.
1) Disconnect the TCM connector (B54 or 
B55).
2) Perform the Clear Memory operation for the 
body integrated unit. <Ref. to LAN(diag)-20, 
CLEAR MEMORY MODE, OPERATION, Sub-
aru Select Monitor.>
3) Read DTC of body integrated unit.

Is DTC (U1202) displayed?

Go to step 5.

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

5

CHECK STEERING ANGLE SENSOR.
1) Disconnect the steering angle sensor con-
nector (B231).
2) Perform Clear Memory Mode for the body 
integrated unit. <Ref. to LAN(diag)-20, CLEAR 
MEMORY MODE, OPERATION, Subaru Select 
Monitor.>
3) Read DTC of body integrated unit.

Is DTC (U1202) displayed?

Go to step 6.

Replace the steer-
ing angle sensor. 
<Ref. to VDC-18, 
REPLACEMENT, 
Steering Angle 
Sensor.>

6

CHECK YAW RATE SENSOR.
1) Disconnect the yaw rate sensor connector 
(B230).
2) Perform Clear Memory Mode for the body 
integrated unit.
3) Read DTC of body integrated unit.

Is DTC (U1202) displayed?

Go to step 7.

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

7

CHECK HARNESS.
1) Disconnect the body integrated unit connec-
tor (B280).
2) Measure the resistance between harness 
connector terminals.

Connector & terminal

(B280) No. 20 — No. 30:

Is the resistance between 55 — 
65 

:?

Go to step 13.

Go to step 8.

8

CHECK HARNESS.
1) Disconnect the body integrated unit connec-
tor (B280).
2) Measure the resistance between harness 
connector terminals.

Connector & terminal

(B280) No. 20 — No. 30:

Is the resistance between 115 — 
125 

:?

Go to step 10.

Go to step 9.

9

CHECK HARNESS.
1) Disconnect the harness connector of body 
integrated unit.
2) Measure the resistance between harness 
connector terminals.

Connector & terminal

(B280) No. 20 — No. 30:

Is the resistance 30 M

: or 

more?

Open circuit in 
related line of body 
integrated unit. 
Repair the open 
circuit of harness 
or replace har-
ness.

Go to step 10.

LAN(diag)-53

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

LAN SYSTEM (DIAGNOSTICS)

10

CHECK HARNESS.
1) Disconnect the VDC/ABS CM connector.
2) Measure the resistance between harness 
connector terminals.

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 11.

Go to step 12.

11

CHECK VDC/ABS CM.
1) Disconnect the VDC/ABS CM connector.
2) Measure the resistance between VDC/ABS 
CM connector terminals.

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 12.

End resistance of 
VDC/ABS CM is 
open. Replace the 
VDC/ABS CM. 
<Ref. to VDC-7, 
VDC Control Mod-
ule and Hydraulic 
Control Unit 
(VDCCM&H/U).>

12

CHECK ECM.
1) Disconnect the ECM connector (B136).
2) Measure the resistance between ECM con-
nector terminals.

Connector & terminal

(B136) No. 27 — No. 35:

Is the resistance between 115 — 
125 

:?

Repair or replace 
the open circuit of 
the harness con-
nector.

End resistance of 
ECM is open. 
Replace the ECM. 
<Ref. to 
FU(H6DO)-38, 
Engine Control 
Module (ECM).>

13

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. 20 — Chassis ground:
(B280) No. 30 — Chassis ground:

Is the resistance less than 10 

:? Go to step 14.

Go to step 15.

14

CHECK CONTROL MODULE.
1) Turn the ignition switch to ON.
2) Disconnect each control module connector 
one by one with the tester connected to vehicle 
side harness.

Connector & terminal

(B280) No. 20 — Chassis ground:
(B280) No. 30 — Chassis ground:

Are there any modules whose 
resistance has become 10 

: or 

more?

 Replace modules 
whose resistance 
has become 10 

:

or more.

Repair or replace 
the short circuit of 
the harness.

15

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

Connector & terminal

(B280) No. 20 (+) — Chassis ground (–):
(B280) No. 30 (+) — Chassis ground (–):

Is the voltage 6 V or more?

Go to step 16.

Go to step 17.

16

CHECK CONTROL MODULE.
1) Turn the ignition switch to ON.
2) Disconnect each control module connector 
one by one with the tester connected to vehicle 
side harness.

Connector & terminal

(B280) No. 20 — Chassis ground:
(B280) No. 30 — Chassis ground:

Is there any module whose volt-
age changes to 6 V or less?

Replace modules 
whose voltage has 
changed to 6 V or 
less.

Repair or replace 
the short circuit of 
the harness.

Step

Check

Yes

No