Subaru Legacy III (2000-2003 year). Manual - part 727

ABS-126

ABS (DIAGNOSTICS)

DIAGNOSTICS CHART WITH SUBARU SELECT MONITOR

AA:DTC 52 OPEN CIRCUIT IN MOTOR RELAY CIRCUIT

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-127

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 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?

Operating sound is produced.

Go to step 4.

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

4

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 5.

Repair connector.

5

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 6.

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

6

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-128

ABS (DIAGNOSTICS)

DIAGNOSTICS CHART WITH SUBARU SELECT MONITOR

AB:DTC 52 MOTOR RELAY ON FAILURE

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-129

ABS (DIAGNOSTICS)

DIAGNOSTICS CHART WITH SUBARU SELECT MONITOR

Step

Value

Yes

No

1

CHECK MOTOR RELAY IN ABSCM&H/U.
Measure resistance between ABSCM&H/U ter-
minals.

Terminals

No. 25 — No. 26:

Does the measured value exceed the specified 
value?

1 M

Ω

Go to step 2.

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

2

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?

There is no poor contact.

Go to step 3.

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

3

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

Operating sound is produced.

Go to step 4.

Repair connector.

4

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 5.

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

5

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.