Subaru Legacy III (2000-2003 year). Service manual — part 728

ABS-130

ABS (DIAGNOSTICS)

DIAGNOSTICS CHART WITH SUBARU SELECT MONITOR

AC:DTC 52 MOTOR MALFUNCTION

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

ABS00298

ABS CONTROL MODULE AND
HYDRAULIC CONTROL UNIT

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

16 17 18 19 20 21 22

27 28 29 30 31

23

24

25

26

F49

25

1

23

26

VALVE RELAY

F49

MOTOR RELAY

FR OUTLET

FR INLET

RL OUTLET

RL INLET

RR OUTLET

RR INLET

FL OUTLET

FL INLET

SOLENOID

VA

L

V

E

PUMP MO

T

O

R

SBF HOLDER 50A

NO

. 10 15A

SBF-4 50A

IGNITION
SWITCH

SBF-1 100A

BATTERY

ABS-131

ABS (DIAGNOSTICS)

DIAGNOSTICS CHART WITH SUBARU SELECT MONITOR

Step

Value

Yes

No

1

CHECK INPUT VOLTAGE OF ABSCM&H/U.
1) Turn ignition switch to OFF.
2) Disconnect connector from ABSCM&H/U.
3) Turn ignition switch to ON.
4) Measure voltage between ABSCM&H/U

connector and chassis ground.

Connector & terminal

(F49) No. 25 (+) — Chassis ground (

−−−−

):

Is the measured value within the specified
range?

10 - 15 V

Go to step 2.

Repair harness/
connector
between battery
and ABSCM&H/U
and check fuse
SBF6.

2

CHECK GROUND CIRCUIT OF MOTOR.
1) Turn ignition switch to OFF.
2) Measure resistance between ABSCM&H/U

connector and chassis ground.

Connector & terminal

(F49) No. 26 — Chassis ground:

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

0.5

Ω

Go to step 3.

Repair
ABSCM&H/U
ground harness.

3

CHECK INPUT VOLTAGE OF ABSCM&H/U.
1) Run the engine at idle.
2) Measure voltage between ABSCM&H/U

connector and chassis ground.

Connector & terminal

(F49) No. 1 (+) — Chassis ground (

−−−−

):

Is the measured value within the specified
range?

10 - 15 V

Go to step 4.

Repair harness
connector
between battery,
ignition switch and
ABSCM&H/U.

4

CHECK GROUND CIRCUIT OF ABSCM&H/U.
1) Turn ignition switch to OFF.
2) Measure resistance between ABSCM&H/U

connector and chassis ground.

Connector & terminal

(F49) No. 23 — Chassis ground:

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

0.5

Ω

Go to step 5.

Repair
ABSCM&H/U
ground harness.

5

CHECK MOTOR OPERATION.
Operate the sequence control. <Ref. to ABS-
9, ABS Sequence Control.>

NOTE:

Use the diagnosis connector to operate the se-
quence control.

Can motor revolution noise (buzz) be heard
when carrying out the sequence control?

Operating sound is produced.

Go to step 6.

Replace
ABSCM&H/U.
<Ref. to ABS-6,
ABS Control Mod-
ule and Hydraulic
Control Unit
(ABSCM&H/U).>

6

CHECK POOR CONTACT IN CONNECTORS.
Turn ignition switch to OFF.
Is there poor contact in connector between
generator, battery and ABSCM&H/U?

There is no poor contact.

Go to step 7.

Repair connector.

7

CHECK ABSCM&H/U.
1) Connect all connectors.
2) Erase the memory.
3) Perform inspection mode.
4) Read out the DTC.

Is the same DTC still being output?

Same DTC is not indicated.

Go to step 8.

Replace
ABSCM&H/U.
<Ref. to ABS-6,
ABS Control Mod-
ule and Hydraulic
Control Unit
(ABSCM&H/U).>

8

CHECK ANY OTHER DTC APPEARANCE.
Are other DTC being output?

Other DTC is not indicated.

A temporary poor
contact.

Proceed with the
diagnosis corre-
sponding to the
DTC.

ABS-132

ABS (DIAGNOSTICS)

DIAGNOSTICS CHART WITH SUBARU SELECT MONITOR

AD:DTC 54 STOP LIGHT SWITCH SIGNAL CIRCUIT MALFUNCTION

DIAGNOSIS:
• Faulty stop light switch
TROUBLE SYMPTOM:
• ABS does not operate.
WIRING DIAGRAM:

ABS00311

2

ABS CONTROL MODULE AND
HYDRAULIC CONTROL UNIT

F49

B64

1 2

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

16 17 18 19 20 21 22

27 28 29 30 31

23

24

25

26

F49

2
3

1
2

STOP LIGHT
SWITCH

B64

B65

:

:

: WITHOUT CRUISE
CONTROL

: WITH CRUISE
CONTROL

B65

1 2
3 4

B62

F45

NO

. 16 20A

BATTERY

SBF-1 100A

WC

OC

WC

OC

WC

OC

SBF-2 50A

6

7

RHD

LHD

:LHD

F45

1 2 3

4 5 6 7

8 9 10 11 12 13 14 15 16

F45

1

2 3

4 5 6 7 8

ABS-133

ABS (DIAGNOSTICS)

DIAGNOSTICS CHART WITH SUBARU SELECT MONITOR

Step

Value

Yes

No

1

CHECK OUTPUT OF STOP LIGHT SWITCH
USING SELECT MONITOR.
1) Select “Current data display & Save” on the

select monitor.

2) Release the brake pedal.
3) Read the stop light switch output in the

select monitor data display.
Is the reading indicated on monitor display
less than the specified value?

1.5 V

Go to step 2.

Go to step 3.

2

CHECK OUTPUT OF STOP LIGHT SWITCH
USING SELECT MONITOR.
1) Depress the brake pedal.
2) Read the stop light switch output in the

select monitor data display.
Is the reading indicated on monitor display
within the specified range?

10 - 15 V

Go to step 5.

Go to step 3.

3

CHECK IF STOP LIGHTS COME ON.
Depress the brake pedal.
Do stop lights turn on?

Stop lights come on.

Go to step 4.

Repair stop lights
circuit.

4

CHECK OPEN CIRCUIT IN HARNESS.
1) Turn ignition switch to OFF.
2) Disconnect connector from ABSCM&H/U.
3) Depress brake pedal.
4) Measure voltage between ABSCM&H/U

connector and chassis ground.

Connector & terminal

(F49) No. 2 — Chassis ground:

Is the measured value within the specified
range?

10 - 15 V

Go to step 5.

Repair harness
between stop light
switch and
ABSCM&H/U con-
nector.

5

CHECK POOR CONTACT IN CONNECTORS.
Is there poor contact in connector between
stop light switch and ABSCM&H/U?

There is no poor contact.

Go to step 6.

Repair connector.

6

CHECK ABSCM&H/U.
1) Connect all connectors.
2) Erase the memory.
3) Perform inspection mode.
4) Read out the DTC.

Is the same DTC still being output?

Same DTC is not indicated.

Go to step 7.

Replace
ABSCM&H/U.
<Ref. to ABS-6,
ABS Control Mod-
ule and Hydraulic
Control Unit
(ABSCM&H/U).>

7

CHECK ANY OTHER DTC APPEARANCE.
Are other DTC being output?

Other DTC is not indicated.

A temporary poor
contact.

Proceed with the
diagnosis corre-
sponding to the
DTC.