Subaru Legacy III (2000-2003 year). Manual - part 788

VDC-188

VDC (DIAGNOSTICS)

DIAGNOSTICS CHART WITH SELECT MONITOR

7

CHECK POOR CONTACT IN CONNECTORS.
Is there poor contact in steering angle sensor?

There is poor contact.

Replace steering 
angle sensor.

Repair or replace 
steering angle 
sensor connector.

8

CHECK VDCCM.
1) Connect connector to VDCCM.
2) Disconnect connector from steering angle 

sensor.

3) Measure resistance between steering 

angle sensor connector terminals.

Connector & terminal

(B231) No. 1 — No. 2:

Is the measured value within the specified 
range?

114 — 126 

Ω

Go to step 10.

Go to step 9.

9

CHECK POOR CONTACT IN CONNECTORS.
Is there poor contact in steering angle sensor?

There is poor contact.

Replace VDCCM.  
<Ref. to VDC-8, 
VDC Control Mod-
ule (VDCCM).>

Repair or replace 
VDCCM connec-
tor.

10

CHECK TCM.
1) Connect connector to TCM.
2) Disconnect connector from VDCCM.
3) Measure resistance between steering 

angle sensor terminals.

Connector & terminal

(B231) No. 1 — No. 2:

Does the measured value exceed the spec-
ified value?

1 M

Ω

Go to step 12.

Go to step 11.

11

CHECK POOR CONTACT IN CONNECTORS.
Is there poor contact in steering angle sensor?

There is poor contact.

Replace TCM.  
<Ref. to AT-76, 
Transmission Con-
trol Module 
(TCM).>

Repair or replace 
TCM connector.

12

CHECK VDCCM.
1) Connect all connectors.
2) Erase the memory.
3) Perform inspection mode.
4) Read out the diagnostic trouble code.

Are other diagnostic trouble codes being 
output?

Other DTC indicated.

Go to step 13.

A temporary poor 
contact.

13

CHECK DIAGNOSTIC TROUBLE CODE.
Is the same diagnostic trouble code as in the 
current diagnosis still being output?

Same DTC indicated.

Go to step 14.

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

14

CHECK AT SYSTEM DIAGNOSTIC TROU-
BLE CODE.
Is the AT system diagnostic trouble code is 
same with the specification?

DTC 86

Replace steering 
angle sensor.

Replace VDCCM.  
<Ref. to VDC-8, 
VDC Control Mod-
ule (VDCCM).>

Step

Value

Yes

No

VDC-189

VDC (DIAGNOSTICS)

DIAGNOSTICS CHART WITH SELECT MONITOR

MEMO:

VDC-190

VDC (DIAGNOSTICS)

DIAGNOSTICS CHART WITH SELECT MONITOR

AG:DTC 48 IMPROPER EAC COMMUNICATION

DIAGNOSIS:
• EAC communication line is broken or short circuited.
TROUBLE SYMPTOM:
• ABS does not operate.
• VDC does not operate.
WIRING DIAGRAM:

VDC00179

C12

A32

F87

56 57

59 60

62 63

65

82 83

80

27

28

25

26

23

24

21

22

19

20

17

18

15

16

13

14

11

12

9

10

7

8

5

6

3

4

1

2

54

55

52

53

50

51

81

48

49

46

47

44

45

78

79

76

77

75

42

43

40

41

74

72

73

70

71

39

37

38

35

36

69

67

68

66

33

34

61

64

31

32

29

30

58

H6

RH4

A24

A24

C11

A33

A25

A25

WO

O

O

LH4

ENGINE

CONTROL

MODULE

B134

B136

A:

:

C:

:

H4

H6

: 4 CYLINDER ENGINE RHD MODEL

: 4 CYLINDER ENGINE LHD MODEL

RH4

LH4

: 4 CYLINDER ENGINE

: 6 CYLINDER ENGINE

H4

H6

: RHD MODEL

: LHD MODEL

R

L

: WITHOUT OBD MODEL

: WITH OBD MODEL

OO

WO

1 2 3

4 5 6

7 8 9 10 11 12 13 14

F96

L

:

F96

R

:

1 2 3 4

5 6 7 8 9

10 11 12 13 14 15 16 17 18 19 20

3

R

12

4

11

L

F96

B255

1 2

7

8 9

5

6

3

4

10 11 12
19 20 21

13 14 15 16

17 18

22 23 24

B136

C:

: H6

B134

A:

: H4

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

45

75

EA

C

EAS

VDC

CONTROL

MODULE

F87

VDC-191

VDC (DIAGNOSTICS)

DIAGNOSTICS CHART WITH SELECT MONITOR

Step

Value

Yes

No

1

CHECK HARNESS BETWEEN ECM AND VD-
CCM.
1) Turn ignition switch to OFF.
2) Disconnect connector from VDCCM and 

ECM.

3) Measure resistance between VDCCM and 

ECM.

Connector & terminal

H4 engine RHD without OBD model

(F87) No. 45 — (B134) No. 24:

H4 engine RHD with OBD model

(F87) No. 45 — (B134) No. 32:

H4 engine LHD model

(F87) No. 45 — (B134) No. 24:

H6 engine model

(F87) No. 45 — (B136) No. 12:

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

0.5 

Ω

Go to step 2.

Repair or replace 
open circuit 
between VDCCM 
and ECM.

2

CHECK GROUND SHORT OF HARNESS.
Measure resistance between VDCCM and 
ECM.

Connector & terminal

(F87) No. 45 — Chassis ground:

Does the measured value exceed the specified 
value?

1 M

Ω

Go to step 3.

Repair or replace 
ground short cir-
cuit between 
VDCCM and ECM.

3

CHECK BATTERY SHORT OF HARNESS.
1) Turn ignition switch to ON.
2) Measure voltage between VDCCM and 

chassis ground.

Connector & terminal

(F87) No. 45 (

++++

) — Chassis ground (

−−−−

):

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

0.5 V

Go to step 4.

Repair or replace 
battery short cir-
cuit between 
VDCCM and ECM.

4

CHECK INPUT VOLTAGE FROM ECM.
1) Turn ignition switch to OFF.
2) Connect connector to VDCCM.
3) Turn ignition switch to ON.
4) Measure voltage between ECM and chas-

sis ground.

Connector & terminal

H4 engine RHD without OBD model

(B134) No. 24 (+) — Chassis ground (

−−−−

):

H4 engine RHD with OBD model

(B134) No. 32 (+) — Chassis ground (

−−−−

):

H4 engine LHD model

(B134) No. 24 (+) — Chassis ground (

−−−−

):

H6 engine model

(B136) No. 12 (+) — Chassis ground (

−−−−

):

Is the measured value within the specified 
range?

10 — 15 V

Go to step 6.

Go to step 5.

5

CHECK POOR CONTACT IN ECM CONNEC-
TORS.
Is there poor contact in ECM connector?

There is poor contact.

Replace ECM.  
<Ref. to 
FU(H6DO)-46, 
Engine Control 
Module.>

Repair or replace 
ECM connector.

6

ERASE MEMORY.
1) Connect all connectors.
2) Erase the memory.

Can the memory be erased?

Can be erased.

Go to step 7.

Replace VDCCM.  
<Ref. to VDC-8, 
VDC Control Mod-
ule (VDCCM).>