1998 BMW M3 key

600
Electrical
System-General

GENERAL
.
...........
.
.
.
.
.
.
.
.
.
...
.
...
600-1

Voltage
and
Polarity
........
.
.
.
.
.
.
.
.....
600-1

Ming,
Fuses
and
Relays
............
.
.
.
.
600-1

Electrical
System
Safety
Precautions
...
.
.
.
.
600-1

Electrical
Test
Equipment
.....
.
.
.
....
.
.
.
.
600-2

WIRING
DIAGRAMS
..
.
.
.
.
.
.
.
.
.
........
600-2

Ming
Codes
and
Abbreviations
..
.
...
.
....
600-2

ELECTRICAL
TROUBLESHOOTING
..
.
..
600-3

Voltage
and
Voltage
Drops
..........
.
.
.
.
.
600-4

GENERAL



Electrical
System
Safety
Precautions

A
brief
description
of
the
principal
parts
of
the
electrical
sys-
tem
is
presented
here
.
Also
covered
here
are
basic
electrical
system
troubleshooting
tips
.

Voltage
and
Polarity

The
vehicle
electrical
system
is
a
12-volt
direct
current
(DC)
negative-ground
system
.
A
voltage
regulator
controls
system
voltage
at
approximately
the
12-volt
rating
of
the
battery
.
Al¡
circuits
are
grounded
by
direct
or
indirect
connection
to
the

negative
(-)
terminal
of
the
battery
.
A
number
of
ground
con-

nections
throughout
the
car
connect
the
wiring
harness
to

chassis
ground
.
These
circuits
are
completedby
the
battery

cable
or
ground
strap
between
the
body
and
the
battery
nega-

tive
(-)
terminal
.

Wiring,
Fuses
and
Relays

Nearly
all
parts
of
the
wiring
harnessconnect
to
compo-

nents
of
the
electrical
system
with
keyed,
push-on
connectors

that
lock
into
place
.
Notable
exceptions
arethe
heavy
battery

cables
and
the
starter
wiring
.
The
wiring
is
color-coded
for
cir-

cuitidentification
.

With
theexception
of
the
battery
charging
system,
most

electrical
power
is
routed
from
the
ignition
switch
or
the
bat-
tery
through
the
main
fuse/relay
panel,
located
in
¡he
left
rear

comer
of
the
engine
compartment
.
Fuses
are
color
coded
to

indicate
current
capacities
.

The
relays
and
control
units/modules
are
mounted
in
vari-

ous
places
throughout
the
vehicle
.
See610
Electrical
Com-

ponent
Locations
.

ELECTRICAL
SYSTEM-GENERAL
600-1

Voltage,
measuring
.
.
.
................
.
.
600-4

Voltage
drop,
testing
.
.
.....
.
.....
.
......
600-4

Continuity,
checking
..
.
...
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
600-5
Short
Circuits
.
.
.
.
.
.
.
.
.....
.
...
.
.
.
.
.
.
.
.
.
600-5

Short
circuit,
testing
with
ohmmete'r
.
.
.
.
.
.
.
.
.
600-6

Short
circuit,
testing
with
voitmeter
.
.
.
.
.
.
.
.
.
600-6

TABLES
a
.
Terminal
and
Circuit
Numbers
..............
..
.600-3
Please
read
the
following
warnings
and
cautions
before
do-
ing
any
work
on
your
electrical
system
.

WARNING
-

"
The
cars
covered
by
this
manual
are
equipped
with
aSupplemental
Restraint
System
(SRS)
that
automatically
deploys
one
or
more
airbags
.
Each
airbag
unit
houses
an
explosive
powerful
charge
.
Any
work
involving
the
SRS
system
should
only
be
performed
byan
authorized
BMW
dealer
.
Making
repairs
without
the
proper
knowledge
and
special
test
equipment
may
cause
serious
per-
sonal
injury
.
See
721
Airbag
System
(SRS)
.

"
The
ignition
system
of
the
car
operates
at
lethal
voltages
.
People
with
pacemakers
or
weak
hearts
should
not
expose
themselves
to
the
ignition
sys-
tem
.
Extra
caution
mustbe
taken
when
working
on
the
ignition
system
or
when
servicing
theen-
gine
while
it
is
runningor
the
key
is
on
.
See
120
Ignition
System
for
additional
ignition
system
warnings
and
cautions
.

"
Before
operating
the
starter
without
starting
the
engine
(as
when
making
a
compressfon
test),
dis-
able
the
ignition
system
as
described
in
120
Igni-
tion
System
.

"
Keep
hands,
clothing
and
other
objects
clear
of
the
electric
radiator
coollng
fan
when
working
on
a
warm
engine
.
The
fan
may
start
at
any
tíme,
even
when
the
ignition
is
switched
off
.

GENERAL

600-
4



ELECTRICAL
SYSTEM-GENERAL

Voltage
and
Voltage
Drops

The
wires,
connectors,
and
switches
that
carry
current
are

designed
with
very
low
resistance
so
that
current
flows
with
a

minimum
loss
of
voltage
.
A
voltage
drop
is
caused
by
higher
than
normal
resistance
in
a
circuit
.
This
additional
resistance

actually
decreases
or
stops
the
flow
of
current
.
A
voltage
drop

can
be
noticed
byproblems
ranging
fromdim
headlights
to
sluggish
wipers
.
Some
common
sources
of
voltage
drops
are
corroded
or
dirty
switches,
dirty
or
corroded
connections
or

contacts,
and
loose
or
corroded
ground
wires
and
ground
con-

nections
.

A
voltage
drop
test
is
a
good
test
to
make
if
current
is
flowing
through
the
circuit,
butthe
circuit
is
not
operating
correctly
.
A
voltage
drop
test
will
help
to
pinpoint
a
corroded
ground
strap
or
a
faulty
switch
.
Normally,
there
should
be
less
than
1
volt

drop
across
most
wires
or
closed
switches
.
A
voltage
drop
across
a
connector
or
short
cable
shouldnot
exceed
0
.5
volts
.

Voltage,
measuring

1
.
Connect
digital
multimeternegative
lead
to
a
reliable
ground
point
oncar
.

NOTE-

The
negative
(-)
battery
terminal
is
alwaysa
good
ground
point
.

2
.
Connect
digital
multimeter
positive
lead
to
point
incir-
cuit
you
wish
to
measure
.
See
Fig
.
1
.
If
a
reading
is
ob-
tained,
current
is
flowing
through
circuit
.

NOTE-

The
voltage
reading
shouldnot
deviate
more
than
1
volt
from
the
voltage
at
the
battery
.
If
the
voltage
drop
is
more
than
this,
check
for
acorroded
connector
or
cose
ground
wire
.

ELECTRICAL
TROLIBLESHOOTING

from
Battery

Fig
.
1
.



Digital
multimeterbeing
used
to
test
voltage
.

No
voltage
r_l

-1
Load

LJ

Switch

NOTE-

The
maximum
voltage
drop
in
an
automotive
circuit,
as
recommended
by
the
Society
of
AutomotiveEngineers
(SAE),
is
as
follows
:
0
voltsfor
small
vire
connections
;
0
.1
Volts
for
high
current
connections
;
0
.2
volts
for
high
current
cables
;
and
0
.3volts
for
switch
or
solenoidcon-
tacts
.
On
longer
wires
or
cables,
the
drop
may
be
slight-ly
higher
.
In
any
case,
a
voltage
drop
of
more
than
1.0volt
usually
indicates
a
problem
.

0013238

NOTE-

"
A
voltage
drop
test
is
generally
more
accuratethan
a



Voltage
drop,
testing

simple
resistance
check
because
the
resistances
in-
volvedare
often
too
small
to
measure
with
most
ohm-



Voltage
drop
can
only
be
checked
when
current
is
running
meters
.
For
example,
a
resistance
as
small
as0
.02



through
the
circuit,
suchasby
operating
the
starter
motor
or
ohms
would
results
in
a
3
volt
drop
in
a
typical
150



turning
onthe
headlights
.
A
digital
multimeter
should
beused
amp
starter
circuit
.
(150
amps
x
0
.02
ohms
=3
volts)
.



lo
ensure
accurate
readings
.

"
Keep
in
mind
that
voltage
with
the
key
on
and
voltage
with
the
engine
running
arenotthe
same
.
With
the
ig-



1
.
Connect
digital
multimeter
positive
lead
to
positive
(+)
nition
on
and
the
engine
off
(battery
voltage),
voltage



battery
terminalor
a
positive
power
supply
close
lo
bat
should
be
approximately
12
.6volts
.
With
the
engine



tery
source
.
running
(charging
voltage),
voltage
should
be
approx-
imately
14
.0
volts
.
Measure
voltage
at
the
battery
with



2
.
Connect
digital
multimeter
negativelead
to
other
end
of
the
ignition
on
and
then
with
the
engine
running
to
get



cable
orswitch
being
tested
.
See
Fig
.
2
.
exact
measurements
.

3
.
With
power
on
and
circuit
working,
meter
shows
volt-
age
drop
(difference
between
two
points)
.
This
value
should
not
exceed
1
volt
.

00-
6



ELECTRICAL
SYSTEM-GENERAL

Short
circuit,
testing
with
ohmmeter



Short
circuit,
testing
with
voltmeter

1
.
Remove
blown
fuse
from
circuit
and
disconnect
cables



1
.
Remove
blown
fusefrom
circuit
.

from
battery
.
2
.
Disconnect
harness
connector
from
circuifs
loador

2
.
Disconnect
harness
connector
from
circuit's
loador



consumer
.

consumer
.

3
.
Using
an
ohmmeter,
connect
one
test
lead
to
loadside

of
f
use
terminal
(terminal
leading
to
circuit)
and
the
oth-

ertest
lead
to
ground
.
See
Fig
.
4
.

Load
disconnected
from
Battery

LO

n
I



~



Shotrouit
vu
.uto
earthth

Switch

Load

0013241

Fig
.
4
.



Digital
multimeter
being
usedasan
ohmmeter
to
find
short

circuit
.

4
.
lf
there
is
continuity
to
ground,
there
is
a
short
to

ground
.

ELECTRICAL
TROUBLESHOOTING

NOTE-

Most
fuses
power
more
than
one
consumer
.
Be
sure
aff

consumers
are
disconnected
when
checking
for
a
short
circuit
.

3
.
Using
a
voltmeter,
connect
test
leads
across
f
use
termi-

nals
.
See
Fig
.
5
.
Make
sure
power
is
present
ín
circuit
.

lf
necessary
turn
keyon
.

~2
.U

from
Battery

Load
disconnected

Short-circuit
to
earth

I



Fuse
box

0013240

5
.
If
there
is
no
continuity,
work
from
wire
harness
hearest



Fig
.
5
.



Digital
multimeter
being
usedas
a
voltmeter
to
find
short
cir

to
fuse/relay
panel
and
move
or
wiggle
wireswhile
ob-



cuit
.

serving
meter
.
Continue
to
movedown
harness
until

meter
displays
a
reading
.
This
is
the
location
of
short
to



4
.
lf
voltage
is
present
at
voltmeter,
there
is
a
short
to

ground
.



ground
.

Visually
inspect
the
wire
harness
at
this
point
for
any
faults
.



5
.
lf
voltage
is
not
present,
work
from
wire
harness
near-

If
no
faults
are
visible,
carefully
slice
open
the
harnesscover



est
to
fuse/relay
panel
and
move
orwiggle
wireswhile

or
the
wire
insulation
for
further
inspection
.
Repair
any
faults



observing
meter
.
Continue
to
move
down
harness
until
found
.



meter
displays
a
reading
.
This
is
the
location
of
short
to

ground
.

6
.
Visually
inspect
wire
harness
atthis
point
for
any
faults
.

lf
no
faults
are
visible,
carefully
slice
open
harness
cov-
erorwire
insulation
for
further
inspection
.
Repair
any

faults
found
.

612-4



SWITCHES
AND
ELECTRICAL
ACCESSORIES

Fig
.
6
.



Ignition
switch
set
screws
(arrows)
.

Ignition
lock
cylinder,
replacing

NOTE-

On
cars
with
EWS
11(production
date
1/95
and
later),
the
ring
antenna
surrounding
the
ignition
switch
must
be
removed
.
See
515
Central
Locking
and
Anti-theft
.

1
.
Insert
master
key
finto
lock
cylinder
and
turn
60°
to
"ra-
dio"
position
.
See
Fig
.
7
.

Fig
.
7
.



Turn
ignition
switch
60°
to
"radio"
position
(arrow)
.

2
.
Insert
a
thin
piece
of
stiff
wire
into
opening
in
lock
cylin-
der
and
pull
lockcylinder
out
.
See
Fig
.
8
.

NOTE-

On
early
cars
(up
to
production
date
1ol95),
turn
lock
cylinder
back
12°
to
release
.

INTERIOR
SWITCHES

0012555
0011807
0011808

Fig
.
8
.



With
ignition
key
in
"radio"position,
insert
stiff
wire
into
lock
opening
to
release
cylinder
.

Headlight
and
Foglight
Switch
Assembly

The
headlight
and
foglight
switches
are
retained
in
the
left

dashboard
insert
.
This
alsocontains
the
driver's
side
face
lev-

e¡
air
vents
.
To
service
either
switch,
remove
insert
byremov-
ing
a
single
screw
.
See
Fig
.
9
.

NOTE-

Access
to
electrical
hamess
connectors
behind
dash
insert
may
be
easier
if
lower
left
dash
trim
and
driverside
knee
bolsterare
removed
.
See
513
Interior
Trim
.

Fig
.
9
.



Remove
retaíning
screw
to
pull
out
left
dash
insert
(arrow)
.

2
.
Using
special
hex
key,
turn
radio
mountingscrews

counterclockwise
to
loosen
.
See
Fig
.
4
.

0011845

Fig
.
4
.



Use
special
hexkey
or
Torx
driver
to
loosen/tighten
radio
mountingscrews
.

3
.
Pul¡
radio
out
of
instrument
panel
opening
.

4
.
Remove
connector(s)
from
rearof
radio
.
See
Fig
.
5
.

Fig
.
5
.



Radio
connector
being
removed
.

5
.
Installation
is
reverse
of
removal
.

0011846

Left
footweil
speaker,

removing
and
installing

Fig
.
6
.



Hood
release
lever
retaining
screw
(arrow)
.

RADIO
650-
3

1
.
Remove
screw
from
center
of
hood
latch
release
lever
.

Remove
lever
.
See
Fig
.
6
.

0012578

2
.
Rotate
plastic
trim
panel
retainer
1
/4
turn
.
Pul¡
off
door

sea¡
from
edge
of
speaker
cover
and
pull
speaker
trim

panel
back
toward
rear
of
car
.
See
Fig
.
7
.

0012579

Fig
.
7
.



Rotate
plastic
retainer
(black
arrow)
andremove
panel
in
di-

rection
shown
(white
arrows)
.

RADIO
AND
SPEAKER
SERVICE

721-2



AIRBAG
SYSTEM
(SRS)

Fig
.
1
.



Airbag
system
components
.

AIRBAG
SENSORSAND
ELECTRONICS

CA
UTION-

"
If
an
airbag
is
activated,
the
following
compo-
nents
must
be
replaced
:
Airbag
with
contact
ring
;
-Pyrotechnic
seat
belt
tensioners
(if
fitted)
;
-SRS
Control
module
;
-Impact
sensors
;
All
airbags
which
did
not
deploy
.

"
Consult
your
BMW
dealer
for
parts
and
service
information
.

TheE36
airbag
system
consists
of
the
following
compo-

nents
:
crash
sensors
(in
earlycars,
through
1993),
an
elec-

tronic
control/monitoring
module
(with
integrated
crash

sensor
in
ZAE
systems),
an
indicator
light
in
the
instrument
panel,
and
inflatable
airbags
equipped
with
gas
generators
in

the
steering
wheel
and
in
the
passenger
side
of
the
instrument

panel
(ZAE
systems)
.

Some
1997
and
al¡
1998
carsalso
have
side-impact
airbags

in
the
front
doors
.

AIRBAG
SENSORS
AND
ELECTRONICS

1.
Crash
sensors
(through
1993)



wheel
2
.



SRS
control
module
in
front
of



5
.



Side-impact
airbags
(1997/98)
glove
compartment
(through



6
.
ZAE
control
module
under
rear
1993)



seat
(from
1994)
3
.



Passenger
side
airbag
unit
in



7
.
Side-impact
airbag
crash
sensors
dashboard
(ZAE
system)



in
door
silis
(1997/98)
4
.



Driver
side
airbag
unitin
steering



8
.



Knee
bolsters

In
addition
to
the
airbags,
the
vehicles
are
equipped
wíth

knee
bolsters
for
extra
protection
.

SRS
Warning
Light
and
Fault
Display

The
airbag
system
utilizes
a
self-diagnostic
control
module

to
detect
and
store
system
faults
.
If
a
fault
is
detected,
the

SRS
indicator
in
the
instrument
cluster
comes
on
and
stays

on
.

When
the
ignition
key
is
tumed
on,
the
indicator
light
will
illu-

minate
for
approximately
4-6
seconds
.
The
illuminated
light

indicates
the
self-testof
the
electronic
control/monitoring

module,
the
ignítors
and
crash-sensorcircuits,
and
the
system

wiring
.
The
airbag
system
should
be
inspected
byan
autho-

rized
BMW
dealer
if
the
indicator
light
does
not
come
on,
ifit

does
not
go
out
in
approximately
4-6
seconds
after
switching

onthe
ignition,
or
if
the
light
comes
on
during
driving
.
If
the

system
has
detected
a
fault,
the
light
will
come
on
and
stay
on
.