Subaru Legacy III (2000-2003 year). Service manual — part 797

VDC-224

VDC (DIAGNOSTICS)

DIAGNOSTICS CHART WITH SELECT MONITOR

AO:DTC 52 MOTOR MALFUNCTION

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-225

VDC (DIAGNOSTICS)

DIAGNOSTICS CHART WITH SELECT MONITOR

Step

Value

Yes

No

1

CHECK CONTACT POINT OF MOTOR RE-
LAY.
1) Turn ignition switch to OFF.
2) Remove motor relay from relay box.
3) Connect battery to motor relay terminals

No. 85 and No. 86.

4) 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 2.

Replace motor
relay.

2

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 3.

Replace motor
relay.

3

CHECK INPUT VOLTAGE OF RELAY BOX.
1) Disconnect connector (F89) from relay box.
2) Disconnect connector from VDCCM.
3) Turn ignition switch to ON.
4) 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 4.

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

4

CHECK INPUT VOLTAGE OF MOTOR RE-
LAY.
1) Turn ignition switch to OFF.
2) Connect connector (F89) to relay box.
3) Turn ignition switch to ON.
4) 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 5.

Replace relay box.

5

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 6.

Tighten the clamp
of motor ground
terminal.

VDC-226

VDC (DIAGNOSTICS)

DIAGNOSTICS CHART WITH SELECT MONITOR

6

CHECK VDCCM MOTOR DRIVE TERMINAL.
1) Turn ignition switch OFF.
2) Remove VDC connector cover. <Ref. to

VDC-19, REMOVE, VDCCM Connector
Cover.>

3) Connect all connectors.
4) Install motor relay.
5) Operate the ABS check sequence. <Ref.

to VDC-16, ABS Sequence Control.>

6) Measure voltage between VDCCM connec-

tor terminals.

Connector & terminal

(F87) No. 22 (+) — No. 1 (

−−−−

):

Does the voltage drop from between 10 V
and 13 V to less than 1.5 V, and rise to
between 10 V and 13 V again when carry-
ing out the check sequence?

Drop from 10 — 13 V to less
than 1.5 V, and rise to 10 — 13
V again when carrying out the
check sequence.

Go to step 7.

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

7

CHECK MOTOR OPERATION.
Operate the check sequence. <Ref. to VDC-
19, VDC Sequence Control.>
Can motor revolution noise (buzz) be heard
when carrying out the check sequence?

Noise heard

Go to step 8.

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

8

CHECK POOR CONTACT IN CONNECTORS.
Turn ignition switch to OFF.
Is there poor contact in connector between
VDCH/U, relay box and VDCCM?

There is poor contact.

Repair connector.

Go to step 9.

9

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

Is the same diagnostic trouble code as in
the current diagnosis still being output?

Same DTC indicated.

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

Go to step 10.

10

CHECK ANY OTHER DIAGNOSTIC TROU-
BLE CODES APPEARANCE.
Are other diagnostic trouble codes being out-
put?

Other DTC indicated.

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

A temporary poor
contact.

Step

Value

Yes

No

VDC-227

VDC (DIAGNOSTICS)

DIAGNOSTICS CHART WITH SELECT MONITOR

MEMO: