Subaru Legacy III (2000-2003 year). Manual - part 714

ABS-74

ABS (DIAGNOSTICS)

DIAGNOSTICS CHART WITH DIAGNOSIS CONNECTOR

Z: DTC 54 ABNORMAL STOP LIGHT SWITCH

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-75

ABS (DIAGNOSTICS)

DIAGNOSTICS CHART WITH DIAGNOSIS CONNECTOR

Step

Value

Yes

No

1

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

Stop lights come on.

Go to step 2.

Repair stop lights 
circuit.

2

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 3.

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

3

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 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.

ABS-76

ABS (DIAGNOSTICS)

DIAGNOSTICS CHART WITH DIAGNOSIS CONNECTOR

AA:DTC 56 ABNORMAL G SENSOR OUTPUT VOLTAGE

DIAGNOSIS:
• Faulty G sensor output voltage
TROUBLE SYMPTOM:
• ABS does not operate.
WIRING DIAGRAM:

ABS00312

F55

R70

F62

ABS CONTROL MODULE AND 
HYDRAULIC  CONTROL UNIT

ABS

G SENSOR

F49

2

1

3

F49

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

3

7

6

28

1

2

3

F55

R49

R70

2

8

30

1

2 3

4 5 6 7 8

ABS-77

ABS (DIAGNOSTICS)

DIAGNOSTICS CHART WITH DIAGNOSIS CONNECTOR

Step

Value

Yes

No

1

CHECK WHEELS FOR FREE TURNING.
Have the wheels been turned freely such as 
when the vehicle is lifted up, or operated on a 
rolling road?

Wheels have not turned freely. Go to step 2.

The ABS is nor-
mal. Erase the 
DTC.

2

CHECK SPECIFICATIONS OF ABSCM&H/U.
Check specifications of the mark to the 
ABSCM&H/U.

CG: AT (Except OUTBACK)
CH: MT (Except OUTBACK)
CI: AT (OUTBACK)
CJ: MT (OUTBACK)

Does the vehicle specification and the 
ABSCM&H/U specification match?

Both are the same specifica-
tions.

Go to step 3.

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

CAUTION:
Be sure to turn ig-
nition switch to 
OFF when remov-
ing ABSCM&H/U.

3

CHECK INPUT VOLTAGE OF G SENSOR.
1) Turn ignition switch to OFF.
2) Remove console box.
3) Disconnect G sensor from body. (Do not 

disconnect connector.)

4) Turn ignition switch to ON.
5) Measure voltage between G sensor con-

nector terminals.

Connector & terminal

(R70) No. 1 (+) — No. 3 (

−−−−

):

Is the measured value within the specified 
range?

4.75 - 5.25 V

Go to step 4.

Repair harness/
connector 
between G sensor 
and ABSCM&H/U.

4

CHECK OPEN CIRCUIT IN G SENSOR OUT-
PUT HARNESS AND GROUND HARNESS.
1) Turn ignition switch to OFF.
2) Disconnect connector from ABSCM&H/U.
3) Measure resistance between ABSCM&H/U 

connector terminals.

Connector & terminal

(F49) No. 6 — No. 28:

Is the measured value within the specified 
range?

5.0 - 5.6 k

Ω

Go to step 5.

Repair harness/
connector 
between G sensor 
and ABSCM&H/U.

5

CHECK GROUND SHORT IN G SENSOR 
OUTPUT HARNESS.
1) Disconnect connector from G sensor.
2) Measure resistance between ABSCM&H/U 

connector and chassis ground.

Connector & terminal

(F49) No. 6 — Chassis ground:

Does the measured value exceed the spec-
ified value?

1 M

Ω

Go to step 6.

Repair harness 
between G sensor 
and ABSCM&H/U.

6

CHECK BATTERY SHORT OF HARNESS.
Measure voltage between ABSCM&H/U con-
nector and chassis ground.

Connector & terminal

(F49) No. 6 (+) — Chassis ground (

−−−−

):

Is the measured value less than the specified 
value?

1 V

Go to step 7.

Repair harness 
between G sensor 
and ABSCM&H/U.