1997 SUBARU LEGACY check

4-4
[M13-51
BRAKES
13
.
Anti-lock
Brake
System
(ABS)
[5
.3i
Type]

5
.
ABSCONTROLMODULEAND
HYDRAULIC
CONTROL
UNIT
(ABSCM&H/U)

*
ABS
CONTROL
MODULE
SECTION
(ABSCM)

The
ABSCM
is
a
digital
control
type
electronic
control
module
accommodating
two
microcontrol

modules
(MCMs)
;
master
and
slave
.
Both
MCMs
process
the
same
program
and
monitor
the

respective
outputs,
and
when
a
mismatch
occurs,
cut
off
the
system
to
activate
the
fail-safe
func-

tion
.

A
maximum
of
3
trouble
codes
are
stored
in
the
EEP
ROM
and
if
3or
more
areas
fail,
then
only
the

3
most
recent
failures
are
stored
.
The
trouble
codes
remain
stored
until
they
are
erased
.

This
ABSCM
inducesa
sequence
control
pattern
and
facilitates
the
checking
of
the
hydraulic
unit
.

"
ABS
control

Based
on
the
four
wheel
speed
signals,
the
ABSCM
calculates
a
simulated
body
speed
or
body

deceleration
rate,
whilereferencing
the
G
sensor
output
asan
auxiliary
means,
and
compares
them
with
the
wheel
speeds
and
wheel
deceleration
rates
.
If
it
determines
that
the
wheels
are

about
to
lock,
it
controls
the
solenoidvalve
or
motor
pump
of
the
H/U
to
adjustthe
brake
fluid
pres-

sures
that
act
on
the
wheel
cylinders,
thereby
preventing
the
wheels
from
locking
.

The
ABSCM
controls
the
right
and
left
front
wheel
fluid
pressures
independently
and
controls
the

rear
wheel
fluid
pressures
on
the
basis
of
the
wheel
which
is
more
likely
to
lock
(Select-low
control)
.

"
Select
monitor
associated
functions

The
Subaru
select
monitor
may
beused
to
perform
the
following
operations
.

O
To
read
out
analogdata
Toread
out
ON/OFF
data

O
Toread
out
or
erase
trouble
code

O
Toread
out
status
information
in
the
event
of
trouble
(Freeze
frame
data)

O
To
initiate
ABS
sequence
control
pattern

"
Indication
functions

The
ABS
warning
light
can
be
made
to
indicate
the
following
three
states
.

O
ABS
trouble

Flashes
to
indicate
trouble
codes
in
diagnosis
mode
.

O
Valve
ON/OFF
when
sequence
control
pattern
isin
effect

6

4-4
[w2sBO]
SERVICE
PROCEDURE

25
.
ABS
Control
Module
and
Hydraulic
Control
Unit
(ABSCM&H/U)
[ABS
5
.3i
Type]

B
:
INSPECTION

i
Mark

>
ABSCM&H/U
B4M
1248A

/Pressure
ga
u
ge
\
'
/\

B4M0633A

1)
Check
connected
and
fixed
condition
of
connector
.

2)
Check
specifications
of
the
mark
with
ABSCM&H/U
.

Mark
Model

C3
AWD
AT

C4
AWD
MT

C
:
CHECKING
THE
HYDRAULIC
UNIT
ABS

OPERATION

1
.
CHECKINGTHE
HYDRAULIC
UNIT
ABS
OPERATION

BY
PRESSURE
GAUGE

1)
Lift-up
vehicle
and
remove
wheels
.

2)
Disconnect
the
air
bleeder
screwsfrom
the
FL
andFR

caliper
bodies
.

3)
Connect
two
pressure
gauges
to
the
FL
andFR
cali-

perbodies
.

CAUTION
:

Pressure
gauges
used
exclusively
for
brake
fluid

must
be
used
.

e
Do
not
employ
pressure
gauge
previously
used
for

transmission
since
the
piston
seal
is
expanded
which

may
lead
to
malfunction
of
the
brake
.

NOTE
:

Wrap
sealing
tape
around
the
pressure
gauge
.

8

SERVICE
PROCEDURE
[w2scI]
4-4

25
.
ABS
Control
Module
and
Hydraulic
Control
Unit
(ABSCM&H/U)
[ABS
5
.3i
Type]

4)
Bleed
air
from
the
pressure
gauges
.

5)
Perform
ABS
sequence
control
.

Ref
.
to
[W25D0]
.*10
>

6)
When
thehydraulic
unit
begins
to
work,
and
first
the

FL
side
performs
decompression,
holding,
and

compression,
and
then
the
FR
side
performs

decompression,
holding,
and
compression
.

7)
Read
values
indicated
on
the
pressure
gauge
and

check
if
the
fluctuationof
the
values
between
decompres-

sion
and
compression
meets
the
standard
values
.
Also

check
if
any
irregular
brake
pedal
tightness
is
felt
.

Initial
value
When
decompressed
When
compressed

Front
wheel
3,432
kPa
(35
kg/cmz,
498
psi)
490kPa
(5
kg/cm2,
71
psi)
3,432
kPa
(35
kg/cm2,
498
psi)

or
less
or
more

Rear
wheel
3,432
kPa
(35
kg/cm2,
498
psi)
490kPa
(5
kg
/cm2,
71
psi)
3,432
kPa
(35
kg/cm2,
498
psi)

or
less
or
more

8)
Remove
pressure
gauges
from
FL
and
FR
caliper
bod-

ies
.

9)
Remove
air
bleeder
screws
from
the
RL
andRR
caliper

bodies
.

10)
Connect
the
air
bleeder
screws
to
the
FL
and
FR
cal-

iper
bodies
.

11)
Connect
two
pressure
gauges
to
the
RL
and
RR
cal-
iper
bodies
.

12)
Bleed
air
from
the
pressure
gauges
and
the
FL
and

FR
caliper
bodies
.

13)
Perform
ABS
sequence
control
.

<
Ref
.
to
[W25D0]
.*10
>

14)
When
thehydraulic
unit
begins
to
work,
at
first
the
RR

side
performs
decompression,
holding,
and
compression,

and
then
the
RL
side
performs
decompression,
holding,

and
compression
.

15)
Read
values
indicated
on
the
pressure
gauges
and

check
if
they
meet
thestandardvalue
.

16)
After
checking,
remove
the
pressure
gauges
from
cal-

iper
bodies
.

17)
Connect
the
air
bleeder
screws
to
RL
and
RR
caliper

bodies
.

18)
Bleed
air
from
brake
line
.

9

4-4
[wzsc2]
SERVICE
PROCEDURE

25
.
ABS
Control
Module
and
Hydraulic
Control
Unit
(ABSCM&H/U)
(ABS
5
.3i
Type]

{~~Y+)~

_~00

G4M0464

2
.
CHECKINGTHE
HYDRAULIC
UNIT
ABS
OPERATION

WITH
BRAKE
TESTER

1)
In
the
case
of
AWD
AT
vehicles,
install
aspare
fuse
with

the
FWD
connector
in
the
engine
compartment
to
simu-

late
FWD
vehicles
.

2)
Prepare
for
operating
ABS
sequence
control
.
<
Ref,to

[W25D1
]*10
or
[W25D2]
.*10
>

3)
Setthe
front
wheels
orrear
wheels
on
the
brake
tester

and
set
the
select
lever's
position
at
"neutral"
.

4)
Operate
the
brake
tester
.

5)
Perform
ABS
sequence
control
.
<
Ref
.
to
[W25D1]*10

step
1
or
[W25D2]*10
step
1
.
>

6)
Hydraulic
unit
begins
to
work
;
and
check
the
following

working
sequence
.

(1)
The
FL
wheel
performs
decompression,
holding,

and
compression
in
sequence,
and
subsequently
the

FR
wheel
repeats
the
cycle
.

(2)
The
RR
wheel
performs
decompression,
holding,

and
compression
in
sequence,
and
subsequently
the

RL
wheel
repeats
the
cycle
.

7)
Read
values
indicated
on
the
brake
tester
and
check

if
the
fluctuationof
values,
when
decompressed
and

compressed,
meet
the
standard
values
.

Unit
:
N
(kg,
Ib)

Initial
value
When
decompressed
When
compressed

Front
wheel
981
(100,
221)
490
(50,
110)or
less
981
(100,
221)
or
more

Rear
wheel
981
(100,
221)
490
(50,
110)
or
less
981
(100,
221)or
more

8)
After
checking,
also
check
if
any
irregular
brake
pedal

tightness
is
felt
.

10

SERVICE
PROCEDURE
[W25D21
4-4

25
.
ABS
Control
Module
and
Hydraulic
Control
Unit
(ABSCM&H/U)
[ABS
5
.3i
Type]

Diagnosis
connector
--J

1

I`

--~
~
''-
Diagnosis
terminals

3
terminal
6
terminal
-
/

B4M0082D
D
:
ABS
SEQUENCE
CONTROL

1)
Under
the
ABS
sequence
control,
after
thehydraulic

unit
solenoid
valve
is
driven,
theoperation
of
thehydrau-

lic
unit
can
be
checked
by
means
of
the
brake
tester
or

pressure
gauge
.

2)
ABS
sequence
control
can
be
started
by
diagnosis

connector
or
select
monitor
.

1
.
OPERATIONAL
GUIDELINES
OF
THE
ABS

SEQUENCE
CONTROL
WITH
DIAGNOSIS
CONNECTOR

1)
Connect
diagnosis
terminals
to
terminals
No
.
3
andNo
.

6
of
the
diagnosis
connector
beside
driver's
seat
heater

unit
.

2)
Setthe
speed
of
all
wheels
at
4
km/h
(2
MPH)
or
less
.

3)
Turn
ignition
switch
OFF
.

4)
Within
0
.5
seconds
after
the
ABS
warning
light
goes

out,
depress
the
brake
pedal
and
hold
it
immediately
after

ignition
switch
is
turned
to
ON
.

CAUTION
:

Do
not
depress
the
clutch
pedal
.

NOTE
:

*
When
the
ignition
switch
is
setto
on,the
brake
pedal

must
not
be
depressed
.

Engine
must
not
operate
.

5)
After
completion
of
ABS
sequence
control,
turn
ignition

switch
OFF
.

2
.
OPERATIONAL
GUIDELINES
OF
THE
ABS

SEQUENCE
CONTROL
WITH
SELECT
MONITOR

NOTE
:

In
the
event
of
any
trouble,
the
sequence
control
may
not

be
operative
.
In
such
a
case,
activate
the
sequence

control,
referring
to
"OPERATIONAL
GUIDELINES
OF
THE

ABS
SEQUENCE
CONTROL
WITHDIAGNOSIS
CONNEC-

TOR
"
.
<
Ref
.
to
4-4
[W25D1],*10>

1)
Connect
select
monitor
to
data
link
connector
beside

driver's
seat
heater
unit
.

2)
Turn
ignition
switch
ON
.

3)
Put
select
monitor
to
ABS
mode
.

11

4-4
[W25D2]
SERVICE
PROCEDURE

25
.
ABS
Control
Module
and
Hydraulic
Control
Unit
(ABSCM&H/U)
[ABS
5
.3i
Type]

[F-101
O
ENT

B4M0635

ABS
FUNCTION

CHECK
MODE

B4M0997
I

BRAKE
ON

KEEP100-150

B4M0998
I

MODE
START
PRESS
ENT
KEY

B4M0999

FUNCTION
START

UNABLE

SWIM

4)
Press
FD
1
ENT
key
.

5)
The
message
shown
in
the
figure
is
displayed
.

6)
The
message
shown
in
the
figure
is
displayed
as
fol-

lows
:

(1)
When
using
the
brake
tester,
depress
brake
pedal

with
braking
force
of
981
N
(100
kg,
221
Ib)
.

(2)
When
using
the
pressure
gauge,
depress
brake

pedalsoas
to
make
the
pressure
gauge
indicate
3,432

kPa
(35
kg/cm2,
498
psi)
.

CAUTION
:

Do
not
depress
the
clutch
pedal
.

7)
When
the
message
shown
in
the
figure
is
displayed,

press
ENT
key
.

8)
Check
points
will
be
displayed
on
select
monitor
.

9)
WhenABS
sequence
control
cannot
be
started
(by

system
malfunction,
etc
.),
the
message
shown
in
the
fig-

ure
will
be
displayed
.

NOTE
:

Read
the
trouble
codes
.
Repair
faulty
parts
.

12

SERVICE
PROCEDURE
[w2sDa1
4-4

25
.
AgS
Control
Module
and
Hydraulic
Control
Unit
(ABSCM&H/U)
[ABS
5
.3i
Type]

AB
S
FUNCTION

CHECK
END

B4M1030

MODE
RESTART?

0
:
YE
S
1
:
NO

H4M
1144

10)
After
completion
of
ABS
sequence
control
.

11)
Press0key
tostart
ABS
sequence
control
again
and

press
1
key
to
end
.

3
.
CONDITIONS
FOR
COMPLETIONOF
ABS

SEQUENCE
CONTROL

When
the
following
conditions
develop,
the
ABS
sequence

control
stops
and
ABS
operation
is
returned
to
the
normal

control
mode
.

1)
When
the
speed
ofat
least
one
wheel
reaches
10
km/h

(6
MPH)
.

2)
When
terminal
No
.
3
or
No
.
6
are
separated
from
diag-

nosis
terminals
.
(When
select
monitor
is
not
used
.)

3)
When
the
brakepedal
is
released
during
sequence

control
and
the
braking
lamp
switch
is
set
to
off
.

4)
When
brake
pedal
is
depressed
afterignition
key
is

turned
to
ON,
and
before
ABS
warning
light
goes
out
.

(When
select
monitor
is
not
used
.)

5)
When
brakepedal
is
not
depressed
after
ignition
key

is
turned
to
ON,
acrd
within
0
.5
seconds
after
ABS
warn-

ing
light
goes
out
.
(When
select
monitor
is
not
used
.)

6)
After
completion
of
the
sequence
control
.

7)
When
malfunction
is
detected
.
(When
select
monitor
is

used
.)

13

4-4d
[T1oo]
BRAKES
[ABS
5
.31
TYPE]

1
.
Supplemental
Restraint
System
"Airbag"
-
2
.
Pre-inspection

1
.
Supplemental
Restraint
System

"Airbag"

Airbagsystem
wiring
harness
is
routed
near
the
ABS

sensor,
ABS
control
module
and
hydraulic
control
unit
.

CAUTION
:

All
Airbag
system
wiring
harness
and
connectors
are

colored
yellow
.
Do
not
use
electrical
test
equipment
on

these
circuit
.

e
Be
careful
not
to
damage
Airbag
system
wiring
har-

ness
when
servicing
the
ABS
sensor,
ABS
control
mod-

ule
and
hydraulic
control
unit
.

2
.
Pre-inspection
Before
performing
diagnostics,
check
the
following
items

which
might
affect
ABS
problems
:

A
:
MECHANICAL
INSPECTION

1
.
POWER
SUPPLY

1)
Measure
battery
voltage
and
specific
gravity
of
electro-

lyte
.

Standard
voltage
:
12
V,
or
more

Specific
gravity
:
Above
1
.260

2)
Check
the
condition
of
the
main
and
other
fuses,
and

harnesses
and
connectors
.
Also
check
for
proper
ground-

ing
.

2
.
BRAKE
FLUID

1)
Check
brake
fluidlevel
.

2)
Check
brake
fluid
leakage
.

3
.
BRAKEDRAG

Check
brake
drag
.
<
Ref
.
to
4-4
[K100].*1
>

4
.
BRAKE
PADAND
ROTOR

Check
brake
padand
rotor
.
<
Ref
.
to
4-4
[K100].*1
>

5
.
TIRE
SPECIFICATIONS,
TIRE
WEARAND
AIR

PRESSURE

Check
tire
specifications,
tire
wear
and
air
pressure
.
<
Ref
.

to
4-2
[S1
A1
],
[S1
A2]
.*1
>

2