Subaru Legacy III (2000-2003 year). Manual - part 768

VDC-108

VDC (DIAGNOSTICS)

DIAGNOSTICS CHART WITH DIAGNOSIS CONNECTOR

AK:DTC 52 ABNORMAL MOTOR AND/OR MOTOR RELAY

DIAGNOSIS:
• Faulty motor
• Faulty motor relay
• Faulty harness connector
TROUBLE SYMPTOM:
• ABS does not operate.
• VDC does not operate.
WIRING DIAGRAM:

VDC00155

VDC HYDRAULIC UNIT

87

87a

VDC2

VDC1

4

6

86

1

85

30

30

86

85

87

5

VDC4

F90

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

SBF HOLDER 50A

VDC7

VDC6

MOTOR RELAY

VALVE RELAY

VDC CONTROL MODULE

22

10

27

47

F87

1

VDC3

F89

2

SBF-1 100A

RELAY BOX

F89

VDC1

1 2

F90

VDC6

1

3

4 5 6

2

85

86

87

30

85 87a 86

87

30

VDC7

BATTERY

VDC-109

VDC (DIAGNOSTICS)

DIAGNOSTICS CHART WITH DIAGNOSIS CONNECTOR

Step

Value

Yes

No

1

CHECK RESISTANCE OF MOTOR RELAY.
1) Turn ignition switch to OFF.
2) Remove motor relay from relay box.
3) Measure resistance between motor relay 

terminals.

Terminals

No. 85 — No. 86:

Is the measured value within the specified 
range?

70 — 90 

Ω

Go to step 2.

Replace motor 
relay.

2

CHECK CONTACT POINT OF MOTOR RE-
LAY.
1) Connect battery to motor relay terminals 

No. 85 and No. 86.

2) Measure resistance between motor relay 

terminals.

Terminals

No. 30 — No. 87:

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

0.5 

Ω

Go to step 3.

Replace motor 
relay.

3

CHECK CONTACT POINT OF MOTOR RE-
LAY.
1) Disconnect battery from motor relay termi-

nals.

2) Measure resistance between motor relay 

terminals.

Terminals

No. 30 — No. 87:

Does the measured value exceed the spec-
ified value?

1 M

Ω

Go to step 4.

Replace motor 
relay.

4

CHECK SHORT OF MOTOR RELAY.
Measure resistance between motor relay ter-
minals.

Terminals

No. 85 — No. 30:
No. 85 — No. 87:

Does the measured value exceed the specified 
value?

1 M

Ω

Go to step 5.

Replace motor 
relay.

5

CHECK INPUT VOLTAGE OF RELAY BOX.
1) Disconnect connector (F89) from relay box.
2) Disconnect connector from VDCCM.
3) Measure voltage between relay box con-

nector and chassis ground.

Connector & terminal

(F89) No. 2 (+) — Chassis ground (

−−−−

):

Is the measured value within the specified 
range?

10 — 15 V

Go to step 6.

Repair harness/
connector 
between battery 
and relay box, and 
check fuse SBF 
holder.

6

CHECK INPUT VOLTAGE OF MOTOR RE-
LAY.
1) Connect connector (F89) to relay box.
2) Measure voltage between relay box and 

chassis ground.

Connector & terminal

(VDC7) No. 87 (+) — Chassis ground (

−−−−

):

Is the measured value within the specified 
range?

10 — 15 V

Go to step 7.

Replace relay box.

VDC-110

VDC (DIAGNOSTICS)

DIAGNOSTICS CHART WITH DIAGNOSIS CONNECTOR

7

CHECK OPEN CIRCUIT IN CONTACT POINT 
CIRCUIT OF RELAY BOX.
1) Turn ignition switch to OFF.
2) Disconnect connectors (VDC2, F90) from 

relay box.

3) Measure resistance between relay box con-

nector unit and motor relay installing por-
tion.

Connector & terminal

(VDC1) No. 1 — (VDC7) No. 30:

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

 0.5 

Ω

Go to step 8.

Replace relay box.

8

CHECK OPEN CIRCUIT IN MONITOR SYS-
TEM CIRCUIT OF RELAY BOX.
Measure resistance between relay box con-
nector and motor relay installing point.

Connector & terminal

(VDC4) No. 6 — (VDC7) No. 30:

Is the measured value less than the specified 
value?

0.5 

Ω

Go to step 9.

Replace relay box.

9

CHECK OPEN CIRCUIT IN CONTROL CIR-
CUIT OF RELAY BOX.
Measure resistance between motor relay 
installing point and relay box connector.

Connector & terminal

(VDC4) No. 4 — (VDC7) No. 86:

Is the measured value less than the specified 
value?

0.5 

Ω

Go to step 10.

Replace relay box.

10

CHECK OPEN CIRCUIT IN CONTROL CIR-
CUIT OF RELAY BOX.
1) Remove valve relay from relay box.
2) Measure resistance between motor relay 

installing point and valve relay installing 
point.

Connector & terminal

(VDC7) No. 85 — (VDC6) No. 30:

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

0.5 

Ω

Go to step 11.

Replace relay box.

11

CHECK GROUND SHORT IN CIRCUIT OF 
RELAY BOX.
Measure resistance between relay box con-
nector unit and chassis ground.

Connector & terminal

(VDC4) No. 4 — Chassis ground:
(VDC4) No. 6 — Chassis ground:

Does the measured value exceed the specified 
value?

1 M

Ω

Go to step 12.

Replace relay box.

12

CHECK BATTERY SHORT IN CIRCUIT OF 
RELAY BOX.
Measure voltage between relay box connector 
and chassis ground.

Connector & terminal

(VDC4) No. 4 (+) — Chassis ground (

−−−−

):

(VDC4) No. 6 (+) — Chassis ground (

−−−−

):

Is the measured value less than the specified 
value?

1 V

Go to step 13.

Replace relay box.

Step

Value

Yes

No

VDC-111

VDC (DIAGNOSTICS)

DIAGNOSTICS CHART WITH DIAGNOSIS CONNECTOR

13

CHECK BATTERY SHORT IN CIRCUIT OF 
RELAY BOX.
1) Turn ignition switch to ON.
2) Measure voltage between relay box con-

nector and chassis ground.

Connector & terminal

(VDC4) No. 4 (+) — Chassis ground (

−−−−

):

(VDC4) No. 6 (+) — Chassis ground (

−−−−

):

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

1 V

Go to step 14.

Replace relay box.

14

CHECK OPEN CIRCUIT IN RELAY CON-
TROL SYSTEM HARNESS.
1) Turn ignition switch to OFF.
2) Measure resistance between VDCCM con-

nector and relay box connector.

Connector & terminal

(F87) No. 22 — (F90) No. 4:
(F87) No. 10 — (F90) No. 6:

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

0.5 

Ω

Go to step 15.

Repair harness 
connector 
between VDCCM 
and relay box.

15

CHECK GROUND SHORT IN HARNESS BE-
TWEEN RELAY BOX AND VDCCM.
Measure resistance between VDCCM connec-
tor and chassis ground.

Connector & terminal

(F87) No. 22 — Chassis ground:
(F87) No. 10 — Chassis ground:

Does the measured value exceed the specified 
value?

1 M

Ω

Go to step 16.

Repair harness 
between VDCCM 
and relay box. 
Check fuse SBF 
holder.

16

CHECK BATTERY SHORT IN HARNESS BE-
TWEEN RELAY BOX AND VDCCM.
Measure voltage between VDCCM connector 
and chassis ground.

Connector & terminal

(F87) No. 22 (+) — Chassis ground (

−−−−

):

(F87) No. 10 (+) — Chassis ground (

−−−−

):

Is the measured value less than the specified 
value?

1 V

Go to step 17.

Repair harness 
between VDCCM 
and relay box. 
Check fuse SBF 
holder.

17

CHECK BATTERY SHORT IN HARNESS BE-
TWEEN RELAY BOX AND VDCCM.
1) Turn ignition switch to ON.
2) Measure voltage between VDCCM connec-

tor and chassis ground.

Connector & terminal

(F87) No. 22 (+) — Chassis ground (

−−−−

):

(F87) No. 10 (+) — Chassis ground (

−−−−

):

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

1 V

Go to step 18.

Repair harness 
between VDCCM 
and relay box. 
Check fuse SBF 
holder.

18

CHECK CONDITION OF MOTOR GROUND.

Tightening torque:

33

±±±±

10 N·m (3.3

±±±±

1.0 kgf-m, 24

±±±±

7 ft-lb)

Is the motor ground terminal tightly clamped?

Clamped securely.

Go to step 19.

Tighten the clamp 
of motor ground 
terminal.

Step

Value

Yes

No