warning SUBARU LEGACY 1997 Service Repair Manual

4-4
LM13-1]
BRAKES
13
.
Anti-lock
Brake
System
(ABS)
[5
.3i
Type]

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

1
.
FEATURE

*
This
ABS
5
.3i
type
incorporates
the
hydraulic
control
unit,
ABS
control
module,
valve
relay
and

motor
relay
in
one
unit
for
betterproductivity
and
lightweight
.

*
The
ABS
(Anti-lock
brake
system)
electrically
controls
brake
fluid
pressure
to
prevent
wheel

"lock"
during
braking
on
slippery
road
surfaces,
thereby
improving
directional/steering
stability
as

well
as
shortening
the
braking
distance
.

*
If
the
ABS
becomes
inoperative,
the
fail-safe
system
activates
to
ensure
it
acts
asa
conventional

brake
system
.
The
warning
light
also
comes
on
to
indicate
that
the
ABS
is
malfunctioning
.

"
The
front-and-rear
wheels
utilize
a
4-sensor,
4-channel
control
design
:
the
front
wheels
havean

independent
control
design*1
and
the
rear
wheels
have
a
select
low
control
design*2
.

*1
:
A
system
which
independently
controls
fluid
pressure
to
left
and
right
front
wheels
.

*2
:
A
system
which
provides
the
same
fluid
pressure
control
for
the
two
rear
wheels
if
either
wheel

starts
to"lock
."

10
ABS
control
moduleand
hydraulic
control
unit
(ABSCM&H/U)
Proportioning
valve
OO
Diagnosisconnector
OO
ABS
warning
light

OO
Data
link
connector
(for
SUBARU
select
monitor)
OO
Transmission
control
module
(only
AT
vehicle)
Tone
wheel

OO
ABS
sensor
09
Wheel
cylinder
O
G
sensor
(only
AWD
vehicle)
>>
Brake
switch
D
Master
cylinder

?15A

2

BRAKES
IM13-21
4-4
13
.
Anti-lock
Brake
System
(ABS)
[5
.3i
Type]

2
.
FUNCTIONS
OF
SENSORS
AND
ACTUATORS

Name
Function

ABS
control
moduleand
hydraulic
ABSCM-
e
Calculates
and
determine
the
conditionsof
the
wheels
and
body
from
control
unit
(ABSCM&H/U)
section
the
wheel
speedsand
makes
a
proper
decision
suitable
for
the
current
situation
to
control
the
hydraulic
unit
.

In
the
ABS
operation
mode,
the
module
outputs
a
cooperative
control
signal
to
the
AT
control
module
.
(AT
vehicles
only)

Whenever
the
ignition
switch
is
placed
at
ON,
the
module
makes
a
self
diagnosis
.
When
anything
wrong
is
detected,
the
module
cuts
off
the
system
.

Communicates
with
the
Subaru
select
monitor
.

H/U-section
In
the
ABS
operation
mode,
the
H/U
changes
fluid
passages
to
control

the
fluid
pressure
of
the
wheel
cylinders
in
response
to
an
instruction
from
the
ABSCM
.

The
H/U
also
constitutes
thebrake
fluid
passage
from
the
master
cylin-
der
to
the
wheel
cylinders
together
with
pipings
.

Valve
relay-
Serves
asa
power
switch
for
the
solenoid
valve
and
motor
relay
coil
in
section
response
to
an
instruction
from
the
ABSCM
.

Motor
relay-
Serves
as
a
power
switch
for
the
pump
motor
in
response
to
an
instruc-
section
tion
from
the
ABSCM
.

Wheel
speed
sensor
(ABS
sensor)
Detects
the
wheel
speed
in
terms
of
a
change
in
the
magnetic
flux
den-
sity
passingthrough
the
sensor,
converts
it
into
an
electrical
signal,
and
outputs
the
electrical
signal
to
the
ABSCM
.

Tone
wheel
Gives
a
change
in
the
magnetic
flux
density
by
the
teeth
around
the
tone
wheel
to
let
the
ABS
sensor
generate
an
electrical
signal
.

G
sensor
(AWD
vehicle
only)
Detects
a
change
in
G
in
the
longitudinal
direction
of
the
vehicle
and
outputs
it
to
the
ABSCM
in
terms
of
a
change
in
voltage
.

Stop
light
switch
Transmits
the
information
on
whether
the
brakepedal
is
depressed
or
not
to
the
ABSCM
for
use
as
a
condition
in
determining
ABS
operation
.

ABS
warning
light
Alerts
the
driver
to
an
ABS
fault
.
When
the
diagnosis
connector
and
diagnosis
terminal
are
connected,
the
light
flashes
to
indicate
a
trouble
codes
in
response
to
an
instruction
from
the
ABSCM
.

AT
control
module
(TCM)
(AT
vehicles
only)
Provides
shift
controls
(fixing
the
speed
at
3rd
or
changing
front
and
rear
wheel
transmission
characteristics
on
4WD
vehicle)
in
response
to
an
instruction
fromthe
ABSCM
.

4-4
[M13-21
BRAKES

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

O

BATTERY

B4H1216A

O
ABS
control
module
and
S
Front
right
outlet
solenoidvalve
D
ABS
warning
light
hydraulic
control
unit
(2
Rear
left
inlet
solenoid
valve'
0
Stop
light
switch
9
ABS
control
module
section
D
Rear
left
outlet
solenoidvalve
0
Stop
light
Valve
relay
0
Rear
right
inlet
solenoidvalve
(5
G
sensor
(only
AWD
model)
O
Motor
relay
8
Rear
right
outlet
solenoid
valve
0
Front
left
ABS
sensor
m
Motor
R
Transmission
control
module
Z
Front
right
ABS
sensor
Front
left
inlet
solenoid
valve
(only
AT
module)
Z
Rear
left
ABS
sensor
8
Front
left
outlet
solenoidvalve
(3
Diagnosis
connector
(8
Rear
right
ABS
sensor
Front
right
inlet
solenoidvalve
0
Data
link
connector

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

BRAKES
[M13-5]
4-413
.
Anti-lock
Brake
System
(AB
S)
[
5
.3i
Typ
e]

"
HYDRAULIC
CONTROL
UNIT
SECTION
(H/U)

The
H/U
is
a
fluid
pressure
controller
comprising
a
motor,
solenoid
valve,
housing,
relay,
etc
.
It

constitutes
two
diagonally
independent
brake
fluid
circuits
for
a
cross
piping
vehicle
.

"
The
pump
motor
rotates
an
eccentric
cam
to
let
the
plunger
pump
generatea
hydraulicpres-

sure
.

"
The
housing
accommodates
the
pump
motor,
solenoid
valve,
reservoir,
etc
.,
and
also
consti-
tutes
abrake
fluid
passage
.

"
The
plunger
pump
is
a
hydraulic
pump
which
drains
off
the
brake
fluid
which,
when
the
pressure

is
reduced,
is
discharged
to
the
reservoir,
and
sends
it
toward
the
master
cylinder
.

"
The
solenoid
valve
is
a
2-position
type
solenoidvalve
which
switches
the
brake
fluid
passages

between
the
wheel
and
master
cylinder
and
reservoir
sides
in
response
to
an
instruction
from
the

ABSCM
.

For
each
wheel
cylinder,
a
pairof
normally-closed
and
-opened
solenoid
valves
are
provided
.

*
The
inlet
solenoid
valve
is
duty-controlled
to
reduce
brake
fluid
pulsation
for
IowerABS
operation

noise
.

"
The
reservoir
is
a
fluid
chamber
which
temporarily
storesthe
brake
fluid
to
be
discharged
from

the
wheel
cylinder
when
the
pressure
is
reduced
.

"
The
damper
chamber
suppresses
thepulsation
of
the
brake
fluid
which,
when
the
pressure
is

reduced,
is
discharged
from
the
plunger
pump,
thereby
minimizing
the
kickbacks
to
the
brake

pedal
.

*
The
valve
relay
controls
the
solenoid
valve
and
motor
relay
energizing
power
supply
in
response

to
an
instruction
from
the
ABSCM
.
In
normal
(1G
ON)
condition,
the
relay
is
actuated
to
supply

power
to
the
solenoid
valve
and
motor
relay
.
When
an
error
occurs
in
the
system,
the
valve
relay

is
forced
to
OFF
to
keep
the
fluid
pressure
circuit
in
the
normal
mode
(normal
brake
mode)
and

also
constitute
the
ABS
warning
light
operating
circuit
.

"
The
motor
relay
supplies
power
to
the
pump
motor
to
operate
the
plunger
pump
in
response
to

an
instruction
from
the
ABSCM
in
the
ABS
control
mode
.

TheH/U
has
four
operating
modes
;
normal
mode
(control
OFF
:
normalbrake
mode),
"increase",

"hold"
and
"decrease"
modes
(control
ON
in
all
the
three
modes)
.

7

4-4
[M13-6l
BRAKES
13
.
Anti-lock
Brake
System
(
AB
S)
[5.3
i
Type]

6
.
ABS
CONTROL
CYCLE
CURVES

Refer
to
4-4
[M8-6]
-*1

7
.
ABS
WARNING
LIGHT

Refer
to
4-4
[M8-7]
-*1

S
.
G
SENSOR

Refer
to
4-4
[M12-8]
.*5

12

BRAKES
44

Page

S
SPECIFICATIONS
AND
SERVICE
DATA

1
.
Brakes

C
COMPONENT
PARTS
...........
.
.
.
.....................
.
.
......
..
.
.
.
..........................

1
.
FrontDisc
Brake

2
.
Rear
Disc
Brake

3
.
Rear
Drum
Brake

4
.
Master
Cylinder

5
.
Brake
Booster

6
.
ABS
System
7
.
Hill
Holder

8
.
Parking
(Hand)
Brake
9
.
ABS/TCS
System

10
.
ABS
System(ABS
5
.3i
Type)
...
....
.
...
..........................
.
.
...
.
.............

W
SERVICE
PROCEDURE
...............
.
.
......
.
.
...
.
....................
.
.
.
.
.
.
...
.
...
.
.......

1
.
Front
Disc
Brake
2
.
Rear
Disc
Brake

3
.
Rear
Drum
Brake
4
.
Parking
Brake
(Rear
Disc
Brake)
5
.
Master
Cylinder

6
.
Brake
Booster

7
.
Brake
Hose
8
.
Hill
Holder

9
.
Parking
Brake
Lever

10
.
Parking
Brake
Cable

11
.
Air
Bleeding
(Without
TCS
model)

12
.
Brake
Fluid
Replacement

13
.
Proportioning
Valve

14
.
ABS
Sensor

15
.
Hydraulic
Unit
for
ABS
System

16
.
ABS
Control
Module

17
.
G
Sensor
for
ABS
System

18
.
Brake
Hose
and
Pipe
am
.
.
.....
.
.................................
.
.
...
.
.....
..

19
.
Air
Bleeding
(With
TCS
model)

20
.
Hydraulic
Unit
for
ABS/TCS
System

21
.
ABS/TCS
Control
Module

22
.
Hydraulic
Unit
for
ABS
System
(ABS
5
.3
Type)

23
.
ABS
Control
Module
(ABS
5
.3
Type)

24
.
G
Sensor
for
ABS
System
(ABS
5
.3
Type)

25
.
ABS
Control
Module
and
Hydraulic
Control
Unit
(ABSCM&H/U)
[ABS
5
.3i
Type]
.
.
.
.
.
.
.
...
.
.
.
.
.
..
.
.
...................................
.
...
.
.
.........
..........
26
.
ABS
Sensor
(ABS
5
.3i
Type)
....
...........................................
.
.
....
.
...
.
27
G
Sensor
(ABS
5
3i
T
e)

2

....
.2

....
.4

........
.
.
..
.4

....
..
.15

....
..
.15
yp
....
.
.
......
...
.
...................................
.
.
.
.
.......
.
.
.....

K
DIAGNOSTICS

1
.
Entire
BrakeSystem

2
.
Hill
Holder

PRECAUTION
FORSUPPLEMENTAL
RESTRAINT
SYSTEM
"AIRBAG"
The
Supplemental
Restraint
System
"Airbag"
helps
to
reduce
the
risk
or
severity
of
injury
to
the
driver
in
a
frontal
collision
.
The
Supplemental
Restraint
System
consists
of
an
airbag
module
(located
in
the
center
of
the
steer-
ing
wheel),sensors,
a
control
module,warning
light,
wiring
harness
and
roll
connector
.
Information
necessary
to
servicethe
safety
is
included
in
the"5-5
.
SUPPLEMENTAL
RESTRAINT
SYSTEM"
ofthis
Service
Manual
.
WARNING
:
"
To
avoid
rendering
the
Airbag
system
inoperative,
which
could
lead
to
personal
injury
or
death
in
the
event
of
a
severe
frontal
collision,
all
maintenance
must
be
performed
byan
authorized
SUBARU
dealer
.
"
Improper
maintenance,
including
incorrect
removal
and
installation
of
the
Airbag
system,
can
lead
to
personal
injury
caused
by
unintentional
activation
of
the
Airbag
system
.
"
All
Airbag
system
electrical
wiring
harnesses
and
connectors
are
covered
with
yellow
outer
insu-
lation
.
Do
not
use
electrical
test
equipment
on
any
circuit
relatedtothe
Supplemental
Restraint
System
"Airbag"
.

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

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

4-4
[W25D4]
SERVICE
PROCEDURE

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

4
.
CONDITIONS
FORABS
SEQUENCE
CONTROL

4
km/h

Speed
of
all
wheels

HIGF
Terminal
No
.3
and
No
.6
LOV1
Operational
guide
lineofIgnition
key
switch
O
sequence
OFF

control
O
ABS
warning
light
OFF

HIGF
Stop
light
switch
LO"

HIGF
AT
ABS
signal
LOW

Valve
relay
ON

OFF

FL
outlet
valve
ON
OFF

FL
inlet
valve
O
NOFF

Operational
FR
outlet
valve
ON
OFF
pattern
of
ON
sequence
FR
inlet
valve
OFF
control
RR
outlet
valve
OFF
RR
inlet
valve
ON
OAF

RL
outlet
valve
OFF

RL
inlet
valve
ONOFF

Pump
motor
OFF

Operational
Pressure
of
master
cylinder

pressure
of
Pressure
of
FLwheel
cylinder
Pressure
of
FR
wheel
cylinder
sequence
Pressure
of
RR
wheel
cylinder
control
Pressure
of
RL
wheel
cylinder

Unit
:
second

B4M1001A
I

NOTE
:

*
When
select
monitor
is
used,
control
operation
starts
at

point
A
.
The
patterns
from
IGN
key
ON
to
the
point
A
show

that
operation
is
started
by
diagnosis
connector
.

HIGH
means
high
voltage
.

LOW
means
low
voltage
.

14