1997 SUBARU LEGACY brake sensor

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

BRAKES
[M13-4]
4-413
.
Anti-lock
Brake
System
(ABS)
[5
.3i
Type]

3
.
THEORY
OF
ABS
CONTROL

Refer
to
4-4
[M8-3]
.*1

4
.
ABSSENSOR

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

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
[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
Iwz7oo1
4-4

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

E
:
INSTALLATION

1)
Install
ABSCM&H/U
.

CAUTION
:

Confirm
that
the
specifications
of
the
ABSCM&H/U
con-

forms
to
the
vehicle
specifications
.

Tightening
torque
:

18
f
5
N~m
(1
.8
±
0
.5
kg-m,
13
.0
±
3
.6ft-Ib)
2)
Connect
brake
pipes
to
their
correct
ABSCM&H/U
con-

nections
.
<
Ref
.
to
[W18A4]
.*10
>

3)
Using
cable
clip,
secure
ABSCM&H/U
harness
to

bracket
.

4)
Connect
connector
to
ABSCM&H/U
.

CAUTION
:

9
Be
sure
to
remove
all
foreign
matter
from
inside
the

connector
before
connecting
.

9
Ensure
that
the
ABSCM&H/U
connetor
is
securely

locked
.

5)
Install
air
intake
duct
.

6)
Connect
ground
cable
to
battery
.

7)
Bleed
air
from
the
brake
system
.

26
.
ABS
Sensor
(ABS
5
.3i
Type)

<
Ref
.
to
4-4
[W1400]
.*1
>

27
.
G
Sensor
(ABS
5
.3i
Type)

Ref
.
to
4-4
[W2400]
.*5
>

15