1994 BMW M3 check engine light
[x] Cancel search: check engine lightPage 164 of 759
130-18
FUEL
INJECTION
The
engine
coolant
temperature
(ECT)
sensor
sends
con-
tinuous
engine
coolant
temperature
information
to
the
ECM
.
Fig
.
26
.
Mass
air
flow
sensor
terminalidentifcation
on
carswith
DME
As
temperature
increases
sensor
resistance
decreases
.
M3
.1
fuel
injection
.
Mass
air
flow
sensor
(hot
film),
testing
and
replacing
MOTE-
A
burn-off
cycle
is
not
used
on
hot
film
sensors
.
8
.
With
ignition
off,
disconnect
harness
connector
from
air
ECT
Sensor
Location
flow
sensor
.
Using
a
digital
multimeter,
check
resis-
"
M50/S50US
engine
............
left
side
of
cylinder
tance
at
terminals
listed
.
head
under
intake
manifold
Air
Flow
Sensor
Test
Values
(DMEM3
.1)
"
Terminals
5
and
6
.
.
.
.........
..
.
..
....
3-4
ohms
If
any
faults
are
found,
check
wiring
lo
and
from
the
ECM
.
Make
ECM
pinout
test
as
listed
in
See
Table
i
.
Main
power
to
air
flow
sensor
comes
from
DME
main
relay
.
On
cars
with
DME
M3
.3
.1
a
hot
film
mass
air
flow
sensor
is
used
.
When
the
engine
is
running,
a
current
is
used
lo
heat
a
thinfilm
in
the
center
of
the
sensor
.
This
current
is
electroni-
cally
converted
into
a
voltage
measurement
corresponding
to
the
mass
of
intake
air
.
If
thehot
film
breaks
or
if
there
is
no
output
from
the
air
flow
sensor,
the
ECM
automatically
switches
to
a
"limp-home"
mode
and
tucos
on
the
Check
Engine
light
.
The
engine
can
usually
be
started
and
driven
.
The
air
flow
sensor
has
no
inter-
nal
moving
parts
and
cannot
be
senricedor
adjusted
.
CA
UTION-
Use
only
a
digital
multimeter
when
checking
the
mass
air
flow
sensor
.
An
analogmetercan
dam-
age
the
air
flow
sensor
.
BOSCH
DME
M3
.
1
AND
M32
.1
COMPONENT
TESTS
AND
REPAIRS
1
.
Disconnect
harnessconnector
from
air
flow
sensor
.
2
.
Turn
ignition
on
and
check
for
voltage
and
ground
at
connector
.
There
should
beground
at
pin
1
.
There
should
be
positive
(+)
battery
voltage
at
pin
3
.
If
any
faults
are
found,
check
wiring
to
and
from
ECM
.
Make
ECM
pinout
test
.
See
Table
j
.
NOTE-
Positive
(+)
battery
voltage
to
air
flow
sensor
comes
from
DME
main
relay
when
the
ignition
is
switch
on
orengine
running
.
Engine
coolant
temperature
(ECT)
sensor,
testing
and
replacing
0012704
Fig
.
27
.
Engine
coolant
temperature
(ECT)
sensor
(A)
is
located
be-
neath
top
engine
cover
(B)
and
crankcase
vent
hose
(C)
.
M52
engine
shown
.
M50
is
similar
.
1
.
Check
ECM
reference
voltage
to
sensor
:
"
Disconnect
harnessconnector
from
ECT
sensor
.
"
Turn
ignition
keyon
.
"
Check
for
5
volts
between
supply
voltage
wire
(brown/red)
wire
of
harness
connector
and
ground
.
"
Turn
ignition
key
off
.
"
If
voltage
is'
not
present
or
incorrect,
check
wiring
from
ECM
and
check
referencevoltage
output
at
ECM
(pin
78)
.
See
Table
i
(DM
E
3
.1)
or
Table
j
(DME
3
.3
.1)
2
.
Check
ECT
sensor
resistance
:
"
With
harnessconnector
disconnected,
check
resis-
tance
acrosssensor
terminals
.
"
Compare
tests
results
to
values
in
Table
f
.
Page 166 of 759
130-20
FUEL
INJECTION
Fig
.
29
.
Throttleposition
sensor
terminal
identification
on
M50
engine
.
Tableg
.
Throttle
Position
Sensor
Tests
(DME3
.113
.3
.1)
Test
conditions
I
Terminals
I
Testvalue
Harness
connector
13
andground
15
VDC
(approx
.)
disconnected,
igni-
in
harness
tion
on
connector
Harness
connector
1
and3
at
sen-
14
k
ohms
(approx
.)
disconnected,
igni-
sor
terminals
tion
off
Throttle
plate
rotat-
1
and
2
at
sen-
Variable
from
1
-
4ked
from
¡dieto
full
sor
terminals
ohms
(approx
.)
with-
throttle
position
out
interruption
¡die
Speed
Control
Valve
Coil
Resistance
Values
"
M50/S50US
engine
NOTE-
Terminals
1
and
2
..
.
................
20
t
5
ohms
On
cars
with
tractioncontrol,
do
not
confuse
the
throttle
Terminals
2
and
3
...................
20
t5
ohms
position
sensor
on
the
main
throttle
body
with
the
throt-
Terminals
1
and
3
..
.
..
:
............
.40
t
5
ohms
tle
positionswitch
on
the
secondary
throttle
body,
where
applicable
.
¡die
speed
control
valve,
testing
¡die
speed
is
maintained
by
the
ECM
through
the
¡die
speed
control
valve
.
The
¡die
controlfunction
compensates
for
engine
load
and
engine
operating
conditions
.
¡die
speed
is
adaptive
through
the
ECM
and
no
¡die
speed
adjustments
can
be
made
.
NOTE-
Before
testing
the
valve,
confirm
that
the
throttle
position
The
idle
speed
controlvalve
receives
positive
(+)
bat-
sensor
is
working
correctly
.
tery
voltage
from
the
main
relay
.
BOSCH
DME
M3
.
1
AND
M3
.3
.1
COMPONENT
TESTS
AND
REPAIRS
NOTE-
"
The
tests
given
below
are
electrical
checks
only
.
They
do
not
check
the
mechanical
operation
of
the
valve
.
If
the
valve
is
suspected
of
causing
poor
idie,
substitut-
ing
a
known
good
valve
is
the
best
way
to
check
for
a
mechanical
fault
.
1
.
With
engine
running,
check
that
¡die
speed
control
valve
is
buzzing
.
2
.
Turn
on
A/C
or
shift
car
finto
drive
.
¡die
should
remain
steady
orincrease
slightly
.
3
.
If
valve
is
not
buzzing,or
if
¡die
decreases
in
step
2,
stop
engine
and
disconnect
harness
connector
from
valve
.
Check
resistance
of
valve
across
its
terminals
.
See
Fig
.
30
.
Test
values
are
listed
below
.
NOTE
-
If
you
suspect
an
intermittent
fault,
lightly
tapthe
valve
while
testing
resistance
.
11250
Fig
.
30
.
¡die
speed
control
valve
terminal
identification
.
4
.
With
valve
harnessconnector
disconnected,
check
for
battery
voltage
at
red/white
wire
in
connector
with
igni-
tion
tumed
on
.
"
If
there
is
no
voltage,
check
wiring
between
connec-
tor
and
main
relayterminal
87
.
See
Electrical
Wiring
Diagrams
.
5
.
If
voltage
is
presentas
described
above,
check
wiring
between
ECM
and
valve
.
If
no
wiring
faults
are
found,
check
ECM
signal
to
valve
.
Page 167 of 759
NOTE-
NOTE-
"
The
Ole
speed
control
valve
signal
can
be
checked
The
intake
manifold
is
held
in
place
with
7
nuts
from
using
a
duty
cycle
meter
(or
dwellmeter)
.
Connect
the
above
and
2
support
bracket
bolts
from
undemeath
.
On
meter
to
the
valve
following
the
manufacturer's
in-
DME
3
.1
cars,
carefully
disconnect
the
idleair
hose
from
structions
.
Turn
on
the
WC
or
create
a
larga
air
leak
theintake
manifold
when
lifting
the
manifold
off
.
For
more
and
check
that
the
meter
reading
reacts
while
the
idle
information,
sea
113
Cylinder
HeadRemovaland
In-
speed
remainssteady
.
stallation
.
"
There
are
some
additional
inputs
to
the
control
mod-
ule
that
affect
idle
speed
(Le
.
throttle
position,
AIC-on
5
.
Disconnect
al¡
necessary
hoses
andremove
idle
speed
signals,
andAIT
Drive
position)
.
Check
these
signals
control
valve
.
if
idle
problems
persist
.
See
Tabla
i
orTable
j
.
Idle
speed
control
valva,
replacing
The
idle
speed
control
valve
is
mounted
beneath
the
intake
manifold
.
Accessing
the
valva
is
best
accomplishedby
first
re-
moving
the
intake
manifold
.
NOTE-
¡tis
recommended
that
the
intake
manifold
gaskets
be
replaced
whenever
the
intake
manifold
is
removed
.
1
.
Remove
top
enginecovers
from
engine
.
See
Fig
.
31
.
FUEL
INJECTION
130-21
6
.
Installation
is
reverse
of
Removal
.
Use
new
gaskets
when
installing
intake
manifold
.
NOTE-
Poor
driveability
may
be
noticed
afterinstalling
a
re-
placement
idle
speed
control
valve
.
After
about
10
min-
utes
of
driving,
the
system
will
adapt
the
base
setting
of
the
valva
and
the
idle
speed
should
retum
to
normal
.
Tightening
Torque
"
Intakemanifold
to
cylinder
head
(M7)
........
..
.
15±2
Nm
(11
ti
ft-Ib)
BOSCH
DME
M5
.2
COMPONENT
REPLACEMENT
On-Board
Diagnostics
11
(OBD
II)
is
incorporated
into
the
Bosch
DME
M5
.2
engine
management
systems
used
on
the
M44
engine
.
OBD
II
is
capable
of
detecting
a
full
range
of
faults
.
When
faults
are
detected,
a
Diagnostic
Trouble
Code
(DTC)
is
stored
in
the
system
ECM
.
The
Check
Engine
warn-
ing
light
will
also
come
on
if
an
emissions-relatad
fault
is
de-
tected
.
The
most
efficient
way
to
diagnose
the
Bosch
OBD
II
sys-
tem
is
by
using
a
specialized
scan
tool
.
The
OBD
II
system
is
capable
of
storing
hundreds
of
faults,
making
diagnostics
with
a
scan
tool
the
only
viable
method
.
Therefore,
system
diag-
nostics
is
not
covered
here
.
Fi
31
.
Remove
to
en
ine
covers
b
in
out
caPs
and
removin
NOTE-
nuts
(A)
9
.
P
g
y
Pry
g
g
"
The
OBD
11
fault
memory
(including
an
iiluminated
Note
14
L-te
at
cover
edge
(arrows)
.
Check
Engine
light)
can
only
be
reset
using
the
spe-
cial
scan
tool
.
Removing
the
connector
from
the
ECM
2
.
Remove
two
hold
down
nuts
from
fuel
injector
wiring
or
disconnecting
the
battery
will
not
arase
the
fault
duct
.
Pry
back
injector
connector
retainers
and
lift
off
memory
.
wiring
duct
.
"
The
16-pin
OBD
Il
diagnostic
connector
is
located
on
the
lower
left
dash
panel
.
Refer
to
Fig
.
1
.
3
.
Disconnect
intake
air
bootfrom
throttle
housing
.
Where
applicable
disconnect
accelerator
cable
and
cruise
"
BMW
special
scan
tool
ora
`generic"OBD
II
scan
tool
control
cable
from
their
brackets
.
must
be
used
to
access
DTCs
.
4
.
Unbolt
intake
manifold
and
move
it
out
of
way
enough
to
access
idle
speed
control
valva
.
"
Tablak
lists
engine
control
module
(ECM)
pinouts
for
the
DMEM5
.2
system
BOSCH
DME
M5
.
2
COMPONENT
REPLACEMENT
Page 169 of 759
001ía4
i
Fig
.
34
.
Intake
air
temperature
(IAT)
sensor
in
top
section
of
air
filter
housing
.
¡die
speed
control
valve,
replacing
side
of
the
throttle
body
.
See
Fig
.
35
.
1
.
Disconnect
harness
connector
from
¡die
valve
.
0012725
Fig
.
35
.
M44
engine
:
Throttle
housing
showing
(A)
throttle
position
sensor
(fPS)
and
(B)
¡die
speed
control
valve
.
2
.
Remove
twomountingscrews
holding
sensor
to
throttle
housing
.
The
¡die
speed
valve
on
the
M44
engine
is
located
on
the
FUEL
INJECTION
130-23
2
.
Disconnect
vacuum
hose
and
retaining
screws
.
3
.
Pull
¡die
speed
control
valve
from
its
fittings
.
4
.
Installation
is
reverse
of
rémoval
.
Always
replace
0-
rings
and
seals
.
NOTE
Poor
driveability
may
be
notíced
after
installing
a
re-
placement
¡dio
control
valve
.
After
about10
minutes
of
driving,
the
idie
speed
should
retum
to
normal
.
SIEMENS
MS
41
.1
COMPONENT
REPLACEMENT
On-Board
Diagnostics
II
(OBD
II)
is
incorporated
into
the
Si-
emens
MS
41
.1
engine
management
systems
used
in
the
M52
and
S52US
engine
.
Refer
to
Fig
.
36
.
OBD
11
is
capable
of
detecting
a
fui¡
range
offaults
.
When
faults
are
detected,
a
Diagnostic
Trouble
Code
(DTC)
is
stored
in
the
system
ECM
.
The
Check
Engine
warning
light
will
also
come
on
if
an
emissions-related
fault
is
detected
.
The
most
efficient
way
to
diagnose
the
Siemens
OBD
II
system
is
by
using
a
specialized
scan
tool
.
The
OBD
II
system
is
capa-
ble
of
storing
hundreds
of
faults,
making
diagnostics
with
a
scan
tool
the
only
viable
method
.
Therefore,
system
diagnos-
tics
is
not
covered
here
.
NOTE
-
"
The
OBD
11
fault
memory
(including
an
illuminated
Check
Engine
light)
can
only
be
reset
using
the
spe-
cial
scan
tool
.
Removing
the
connector
from
the
ECM
or
disconnecting
the
battery
will
not
erase
the
fault
memory
.
"
The
16-pin
OBD
11
diagnostic
connector
is
located
on
the
lower
left
dash
panel
.
Refer
to
Fig
.
1
.
"
BMW
special
scan
tool
ora
"generic"
OBD
11scan
tool
must
be
used
to
access
DTCs
.
3
.
Installation
is
reverse
of
removal
.
No
adjustment
is
nec
essary
.
"
Table
1
lists
engine
control
module
(ECM)
pinouts
forthe
MS
41
.1
systems
.
SIEMENS
MS
41
.
1
COMPONENT
REPLACEMENT
Page 217 of 759
Fig
.
3
.
Clutch
master
cylinder
mounting
bolts
.
Clutch
slave
cylinder,
replacing
0012589
Tightening
Torques
"
Clutch
master
cylinder
to
bulkhead
..
22
Nm
(17
ft-Ib)
"
Fluid
line
to
master
cylinder
orslave
cylinder
.................
16
Nm
(12
ft-1b)
The
clutch
slave
cylinder
is
mounted
on
the
left
side
of
the
transmission
.
CLUTCH
MECHANICAL
1
.
Remove
brake
fluid
reservoir
cap
.
Using
a
clean
sy-
ringe,
remove
brake
fluid
from
reservoir
.
2
.
Disconnect
fluid
hose
from
slave
cylinder
.
Place
a
pan
under
hose
to
catch
any
excess
fluid
.
3
.
Unbolt
slave
cylinder
from
transmission
.
See
Fig
.
4
.
4
.
Installation
is
reverse
of
removal,
noting
the
following
:
"
Check
for
wear
on
pushrod
.
Any
other
wear
except
on
tipis
caused
by
misalignment
of
clutch
components
.
"
Lightly
coat
pushrod
tip
with
molybdenum
disulfide
grease
(Molykote
0
Longterm
2
or
equivalent)
.
"
During
installation
be
sure
pushrod
tip
engages
recess
in
clutch
release
lever
.
"
Fill
fluid
reservoir
with
clean
fluid
.
"
Bleed
clutch
hydraulics
as
described
earlier
.
CLUTCH
210-
3
Fig
.
4
.
Clutch
slave
cylinder
mounting
bolts
(arrows)
.
Tablea
.
ClutchDisc
Diameter
Model
Diameter
3181/is/iC
215
mm
(8
.46
in)
325i/is/iC
228
mm
(8
.98
in)
323is/iC
328i/is/iC
240
mm
(9
.45
in)
M3
0012715
Tightening
Torques
"
Clutch
slave
cylinder
to
transmission
.
.
................
22
Nm
(17
ft
lb)
"
Fluid
line
to
slave
cylinder
......
.17
Nm
(10-12
ft
lb)
The
transmission
must
be
removed
from
the
engine
to
ac-
cess
the
clutch
mechanical
components
.
It
is
recommended
that
the
clutch
disc,
pressure
plate
and
release
bearing
be
re-
placed
duringa
clutch
overhaul
.
Be
sure
to
check
the
bottom
of
the
bellhousing
for
oil
.
If
engine
oil
is
found,
check
for
a
faulty
rear
crankshaft
oil
seal
.
CLUTCH
MECHANICAL
Page 221 of 759
230
Manual
Transmission
MANUAL
TRANSMISSION
230-1
GENERAL
...
.
............
.
.......
.
.
.
.
230-1
Output
shaft
sea¡,
replacing
(transmission
installed)
....
.
.....
.
.....
.230-4
TRANSMISSION
FLUID
SERVICE
.
.
.
.
.
.
.230-1
Inputshaft
sea¡,
replacing
Transmission
fluid
leve¡,
checking
...
.
...
.
.
230-2
(transmission
removed)
.
.
.
.
...
.
.
.
.....
.
230-5
Transmission
fluid,
replacing
.........
.
.
.
.
230-2
TRANSMISSION
REMOVAL
AND
TRANSMISSION
SERVICE
.
.
.....
.
.
.
.
.
.
230-2
INSTALLATION
.
.
.
.
.
.
.....
.
.
.
.
.
.
.
.....
.
230-5
Back-up
light
switch,
replacing
.
.
.
...
.
.
.
.
.
.
230-2
Transmission,
removing
and
installing
...
.
.
.
.
230-6
_
Selector
shaft
sea¡,
replacing
(transmission
installed)
.
.
.
.
.
.
.
.
.
.
.
...
.
.
230-3
TAB
a
.
Manual
Transmission
Gear
Ratios
.
.
.
.........
.230-1
GENERAL
TRANSMISSION
FLUID
SERVICE
This
repair
group
covers
external
transmission
service,
in-
The
manual
transmissions
installed
in
the
E36
models
are
cluding
removal
and
installation
of
thetransmission
unit
.
Inter-
normally
filled
with
automatic
transmission
fluid
(ATF),
al-
nal
transmission
repair
is
not
covered
.
Special
press
tools
and
though
alternative
lubricants
may
have
beenused
from
the
procedures
are
required
to
disassemble
and
service
the
inter-
factory,
depending
on
transmission
type
and
model
year
.
For
nal
geartrain
.
example,
transmissions
fitted
to
the
M3
models
are
normally
filled
with
a
"lifetime"
manual
transmission
fluid
(BMW
MTF
Manual
transmissions
used
are
based
on
engine
applica-
LT-1)
and
do
not
require
periodic
fluid
changes
.
tion
.
Consult
200
Transmission-General
for
transmission
application
information
.
Table
a
lists
gear
ratio
specifications
.
NOTE-
The
transmission
lubricant
type
can
be
found
ona
label
NOTE-
on
the
sideof
the
transmission
.
Consult
an
authorized
Do
not
rely
on
forged
casting
numbers
for
transmission
BMW
dealer
for
altemate
fluid
use
and
the
most-up-to-
code
identification
.
date
information
regarding
transmission
operating
fluids
.
Tablea
.
Manual
Transmission
Gear
Ratios
Transmission
1
Getrag
S5D
200
G
1
Getrag
SSD
250
G
1
ZF
S5D
310
Z
1
ZF
S5D
320
Z
Gear
Ratios
:
1st
4
.23
4
.23
4
.20
4
.20
2nd
2
.52
2
.52
2
.49
2
.49
3rd
1
.66
1
.66
1
.66
1
.664th
1
.22
1
.22
1
.24
1
.24
5th
1
.00
1
.00
1
.00
1
.00
reverse
4
.04
4
.04
3
.89
3
.89
TRANSMISSION
FLUID
SERVICE
Page 291 of 759
Brake
rotor,
removing
and
installing
.
.
.
.
.
.
.
.
340-7
MASTER
CYLINDER
............
.
.
.
.
.
.
.340-7
Master
cylinder,
removing
and
installing
.
...
.
340-7
GENERAL
TROUBLESHOOTING
WARNING
-
"
Although
semi-metallic
and
metallic
Brake
friction
materials
in
Brake
pads
or
shoes
no
longer
con-
tain
asbestos,
they
produce
dangerous
dust
.
"
Brake
fluid
is
poisonous,
highly
corrosive
and
dangerous
to
the
environment
Wear
safety
glasses
and
rubber
gloves
when
working
with
Brake
fluid
.
Do
not
siphonBrake
fluid
with
your
mouth
.
Immediately
clean
away
any
fluid
spilled
on
painted
surfaces
and
wash
with
water,
asBrake
fluid
will
remove
paint
.
"
Always
use
new
Brake
fluid
froma
fresh,
un-
opened
container
.
Brake
fluid
will
absorb
mois-
ture
from
the
air
.
This
canlead
to
corrosion
problems
in
the
brakingsystem,
and
will
also
low-
er
the
Brake
fluid's
boiling
point
.
Dispose
of
Brake
fluid
properly
.
"
Do
notreuse
self-locking
nuts,bolts
or
fasteners
.
They
are
designed
to
be
used
only
once
and
may
failif
reused
.
Always
replace
them
with
new
self-
locking
fasteners
.
BMW
E36
models
areequipped
with
vacuum
power-assist-
ed
four-wheel
disc
brakes
with
an
integral
Antilock
Brake
Sys-
tem
(ABS)
.
Single-pistoncalipers
act
on
solid
or
vented
front
rotors
and
solid
rear
rotors
.
A
brake
pad
wear
sensor
for
each
axle
indicates
when
brake
padsneed
replacement
.
The
dual
drum-type
parking
brakesystem
is
integrated
with
the
rear
brake
rotors
.
NOTE-
M3
models
havevented
directional
Brake
rotors
on
the
rearaxle
as
well
ason
the
front
.
340
Brakes
BRAKES
340-1
GENERAL
.
.
.
.
.
.
.........
.
.
.
..........
340-1
BRAKE
BOOSTER
.........
.
.
.
.
.
...
.
.
.
.
340-8
TROUBLESHOOTING
.......
.
......
.
...
340-1
Brake
booster,
removing
and
installing
....
.
.
340-8
PARKING
BRAKE
.
.....
.
...
.
.
.
.....
.
.
.
340-10
BLEEDING
BRAKES
.
.
.
.
.
.
.
.
..........
340-3
Parking
brake,adjusting
.
.
.
.
.
.
.
.
.
.
.....
.
340-10
Pressure
bleeding
brakes
Parking
brake
shoes,
removing
and
installing
.
340-11(except
cars
with
AST)
.
.
.
.
.
.
.
.
.
...
.
.
.
.
.340-3
Parking
Brake
cable,
replacing
.
.
.
.
.
.
.
.
.
.
.
.
340-11
BRAKE
PADS,
CALIPERS,
ANTILOCK
BRAKE
SYSTEM
(ABS)
.
.
.
.340-11
AND
ROTORS
..........
.
.......
.
.
.
.
.
.
.
340-3
ABS
System
Inspection
.
...
.
.......
.
.
.
..
340-12
Brake
pads,
replacing
............
.
.
.
.
.
.
.
340-4
ABS
wheel
speed
sensors,
replacing
.
.
.
.
..
340-12
Brake
caliper,
removing
and
installing
.
..
..
.
340-6
TABLES
a
.
Brake
System
Troubleshooting
.....
...
.
.
.....
.340-2
b
.
Brake
Rotor
Reconditioning
Specifications
.
.....
.340-7
Brakeperformance
is
mainly
affected
by
three
things
:
the
leve¡
and
condition
of
the
brake
fluid,
the
system's
abilíty
to
create
and
maintain
hydraulic
pressure,
and
the
condition
of
the
friction
components
.
Air
in
the
Brake
fluid
will
make
the
Brake
pedal
feel
spongy
during
braking
or
will
increase
the
Brake
pedalforce
required
to
stop
.
Fluid
contaminated
by
moisture
or
dirt
can
corrode
the
system
.
Inspect
the
Brake
fluid
inside
the
reservoir
.
Ifit
is
dirty
or
murky,
or
is
over
a
year
old,
the
fluid
should
be
replaced
.
Visually
check
the
hydraulic
system
startingat
the
master
cylinder
.
To
check
the
function
of
the
master
cylinder
hold
the
brake
pedal
down
hard
with
the
engine
running
.
The
pedal
should
feelsolid
and
stay
solid
.
If
the
pedal
slowly
falls
to
the
floor,
either
the
master
cylinder
is
leaking
internally,
or
fluid
is
leaking
externally
.
If
no
leaks
canbe
found,
the
master
cylin-
der
is
faulty
and
should
be
replaced
.
Check
all
Brake
fluid
lines
and
couplings
for
leaks,
kinks,
chafing
and
corrosion
.
Check
the
Brake
booster
by
pumping
the
Brake
pedal
ap-
proximately
10
times
with
the
engine
off
.
Hold
the
pedal
down
and
start
the
engine
.
The
pedal
should
fa¡¡
slightly
.
If
not,
check
for
any
visiblefaults
before
suspecting
a
faulty
brake
booster
.
Check
for
strong
vacuum
at
the
vacuum
hose
fitting
at
the
booster,
and
check
the
non-retum
valve
for
one-way
flow
.
Worn
or
contaminated
brake
pads
will
cause
poor
braking
performance
.
Oil-contaminated
or
glazed
pads
will
cause
stopping
distances
to
increase
.
Inspect
the
rotors
for
glazing,
discoloration
and
scoring
.
Steering
wheel
vibration
while
braking
at
speed
is
often
caused
by
warped
rotors,
but
can
also
be
caused
byworn
suspension
components
.
TROUBLESHOOTING
Page 299 of 759
6
.
Disconnect
ABS
electrical
connectors
.
Label
and
then
disconnect
brake
lines
from
hydraulic
brake
unit
.
Plug
openíngs
.
See
Fig
.
12
.
~
~
A
1/
B
'1v
C
~
F
lu
11
-ri
J
.
0013244
A
.
Right
front
F
Front
from
master
cylinder
B
.
Leftfront
R
.
Rear
from
master
cylinder
C
.
Rear
Fig
.
12
.
Brake
fluid
linesat
ABS
hydraulic
unit
.
WARNING
-
"
On
cars
with
All
Season
Traction
(AST),
special
BMW
service
equipment
is
required
to
properly
bleed
the
Antilock
Brake
System
(ABS)
.
Removal
of
the
ABS
hydraulic
unit
is
not
recommended
un-
less
this
equipment
is
available
.
For
safetyrea-
sons,
the
brake
system
on
cars
with
ABS
must
not
be
bled
using
the
procedures
described
inthis
repair
group
.
"
Do
not
mix
up
the
fluid
fines
at
the
ABS
hydraulic
unit
Label
all
connections
before
disconnecting
.
7
.
Remove
ABS
hydraulic
unit
from
engine
compartment
.
8
.
Working
inside
car,
remove
panel(s)
frombeneath
steering
column
to
access
pedal
assembly
.
See513
In-
terior
Trim
.
12
.
Make
sure
al¡
nuts,
fluid
couplings,
thread
bores
and
mating
surfaces
are
clean
.
BRAKES
340-
9
0011261
Fig
.
13
.
Brake
pedal
clevispin
and
retaining
clip
(A)
.
Brake
booster
mounting
nuts
shown
at
arrows
.
13
.
If
necessary,
mount
master
cylinder
to
vacuum
booster
using
a
new
O-ríng
and
newself-locking
nuts
.
CAUTION-
Do
not
over-torque
the
master
cylinder
mounting
bolts
.
This
could
damage
the
brake
booster
and
prevent
proper
vacuum
build-up
.
14
.
Installation
is
reverse
of
Rmoval
.
"
Bleed
brakes
as
described
earlier
.
"
Check
and,
if
necessary,
adjust
brake
light
switch
above
brake
pedal
.
Tightening
Torques
"
Brakemaster
cylinder
to
brake
booster
...........
.
..
..
...
26
Nm
(18
ft-Ib)
"
Brake
booster
to
bulkhead
.
.
..
..
...
22
Nm
(16
ft-Ib)
"
Brake
fluidline
to
master
cylinder
or
ABS
hydraulic
unit
.......
.
..
17-19
Nm
(13-14
ft-lb)
9
.
Remove
clip
and
clevis
pin
from
brake
booster
pushrod
and
disconnect
it
from
brakepedal
.
Remove
brake
booster
mounting
nuts
.
See
Fig
.
13
.
NOTE-
10
.
Working
in
engine
compartment,
remove
brake
booster
When
replacing
the
brake
booster
one-way
valve
or
together
with
master
cylinder
.
vacuum
hose,
install
the
valve
so
that
the
molded
arrow
is
pointing
toward
the
intake
manifold
.
Use
new
hose
11
.
If
booster
or
master
cylinder
O-ring
is
being
replaced,
clamps
.
disconnect
master
cylinder
from
brake
booster
.
BRAKE
BOOSTER