1996 BMW 318i electrical wiring diagram ignition switch

General
Data
and



010
FundamentalsfortheDo-lt-YourselfOwner

Maintenance



020
Maintenance
Program

Engine

Transmission

Suspension,

Steering
and

Brakes

4
Body

100
Engine-General

110



Engine
Removal
and
Installation
113



Cylinder
Head
Removal
and
Installation
116



Cylinder
Head
and
Valvetrain
117



Camshaft
Timing
Chain

119



Lubrication
System

200
Transmission-General
210
Clutch
230
Manual
Transmission

510



Exterior
Trim,
Bumpers



520



Seats

Bo
y
Equipment



512
DoorWTdws



540



nr
t

513



InteriorTrim



541



Convertible
Top

515



Central
Locking
and
Anti-Theft

600



Electrical
System-General



620



Instruments

Electrical
S



stem
610
Electrical
Component
Locations



630
Exterior
Lighting

611



Wipers
and
Washers



640



Heating
and
Air
Conditioning

6



612



Switches
and
Electrical
Accessories



650



Radio

Equipment
and



720
SeatBelts

Accessories



721
Airbag
System
(SRS)

Electrical
Wiring

Diagrams

Foreword
.
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.
...
.
.
.
.
.
................
.
.
.
.....
.
......
.
................
.
.
.
.....
v

Warnings
and
Cautions
.....
.
...
.
.
.
.
.
..........
.
...
.
.
.
.
.
......
.
.........
.
.
.
...
.
.
.
......
.
.
.
.
.
............
.
.
.
.
.
.
.vii

Index
..............
.
.
.
.....
.
............
.
...
.
.
.
.
.
........
.
...
.
.
.
.
.
.......
.
......
.
...
.
.
.
.
.
.
.
........
.
.
.
..
back
of
book

300



Suspension,
Steering
and



330



RearSuspension

Brakes-General



331



Final
Drive

310



Front
Suspension



340



Brakes

320



Steering
and
Wheel
Alignment

400
Body-General



411
Doors

410



Fenders,
Engine
Hood



412



Trunk
Lid

120



Ignition
System
121



Battery,Starter,
Alternator
130



Fue¡
Injection
160



Fuel
Tank
and
Fuel
Pump
170



Radiator
and
Cooling
System180



Exhaust
System

240



Automatic
Transmission
250



Gearshift
Linkage

260
Driveshaft

119-2



LUBRICATION
SYSTEM

NOTE-
Component
Location



If
the
light
does
not
go
out,
thewiring
to
theswitch
is"
Oil
pressure
switch



most
likely
grounded
somewhere
between
the
switch

all
engines
.......
...
.
..
......
ora
oil
filter
housing



terminal
and
the
warning
light
.
Sea
Electrical
Wiring

Diagrams
atrearof
manual
for
electrical
schematics
.

CAUTION-

Some
oil
may
drain
out
as
the
oil
pressure
switch
is
removed
.
Use
a
rag
to
soak
up
any
spills
.

2
.
Install
pressure
gauge
in
place
of
switch
.

3
.
With
gauge
instalied,
start
engine
and
allow
to
reach

operating
temperature
.
Check
oil
pressureboth
cold

and
hot
.

NOTE-

For
the
most
accurate
test
results,
the
engine
oil
(and
filter)
shouldbe
newand
of
the
correct
grade
.

Oil
Pressure

"
¡dle
(mínimum)
..
.
.
..............
.
.
0
.5
bar
(7psi)

"
Regulated
pressure
(elevated
engine
speed)

4-cylinder
engines
..
......
4
.3
±
0
.2
bar
(63
t3
psi)

6-cylinder
engines
.
.
.............
.
4
.0
bar
(59
psi)

4
.
Remove
pressure
gauge
and
reinstall
pressure
switch
.

If
testing
shows
low
oil
pressure,
one
or
more
of
the
follow-

ing
conditions
may
be
indicated
:
OIL
PAN

"
Worn
or
faulty
oii
pump
.

"
Worn
or
faulty
engine
bearings



The
oil
pancan
be
removed
with
the
engine
instalied,
al-

Severe
engine
wear
.



though
specíal
enginesupport
equipment
will
be
needed
.

Al¡
of
these
conditionsindicate
the
need
for
major
repairs
.

Oil
pressure
warning
system,
testing

When
the
ignition
is
tumed
ora,
the
oil
pressure
warning
light

comes
ora
.
When
the
engine
ís
started
and
the
oil
pressure
ris-

es
slightly,
the
oil
pressure
switch
opens
and
thewarning
light

goes
out
.
Make
sure
the
oil
leve¡
is
correct
before
making

tests
.

1
.
Turra
ignition
switch
ora
.

"
Warning
light
ora
instrument
panel
must
light
up
.

2
.
Remove
connector
from
oil
pressure
switch
.

"
Warning
light
ora
instrument
panel
must
go
out
.

OIL
PAN

3
.
If
warning
light
does
not
light
when
ignition
is
ora,
re-

move
connector
from
oil
pressure
switch
anduse
a

jumper
wire
to
ground
connector
terminal
to
a
clean

metal
surface
.

NOTE
-

If
the
warning
light
comes
ora,
check
the
switch
as
de-
scríbed
in
the
nextstep
.
If
the
warning
light
does
not
come
ora,
thewiring
to
the
instrument
cluster
or
to
the

light
itself
isfaulty
.

4
.
To
test
switch,
connect
ara
ohmmeter
between
terminal

in
switch
body
and
ground
.
With
engine
off,
these

should
be
continuity
.
With
engine
running,
oil
pressure

should
opera
switch
and
there
should
beno
continuity

Replace
a
faulty
switch
.

WARNING
-

Keep
in
mind
that
low
oil
pressure
may
be
prevent-

ing
the
switch
from
tuming
the
light
out
.
If
the
light

remains
ora
while
the
engine
is
running,
check
the

oil
pressure
asdescribed
earlier
.
Do
not
drive
the
car
until
the
problem
is
corrected
.
Theengine
may
be
severely
damaged
.

Oil
pan,
removing
and
installing

(4-cylinder
engines)

1
.
Raise
car
arad
place
securely
ora
jackstands
.

2
.
Remove
splash
shíeld(s)
from
under
engine,
where
ap-

plicable
.

3
.
Drain
engine
oil
as
described
in
020
Maintenance
Pro-
gram
.

4
.
Disconnect
vacuum
hose
adapter
from
vacuum
brake

booster
at
rear
of
engine
compartment
.

5
.
Remove
oil
dipstick
guide
tube
mounting
nut
and
pull
guide
tube
from
oil
pan
.
See
Fig
.
2
.

120-
4



IGNITION
SYSTEM

2
.
Check
for
battery
voltage
o
cofs
.
If
voltage
is
not



Table
b
.
Ignition
Coil
Resistance

present,
check
wire
between
terminal
15
and
ignition



(M42
Engine)
switch
.
See
Electrical
Wiring
Diagrams
.

"
On
M42
engine,
connect
digital
multimeter
between
ter-

minal
15(+)
in
each
harness
connector
and
ground
.
See

Fig
.
4
.

"
On
M44
engine,
connect
voltmeter
between
terminal
2

(15+)
in
connector
and
ground
.
Turn
ignition
on
and

check
for
voltage
.
See
Fig
.
5
.

3
.
Turn
ignition
off
.

0
4a15

Fig
.
4
.



Ignition
coil
harness
connector
terminal
identification
for
M42

engine
.

Fig
.
5
.



Ignition
coil
harness
connector
terminal
identification
for
M44
engine
.

CAUTION-

The
wiring
to
the
coil(via
the
ignition
switch
15+)
is
not
fuse
protected
.
Use
care
when
testing
thiscircuit
.

4
.
Use
a
digital
multimeter
totest
coil
primary
resistance
.

"
On
M42
engine,
use
Table
b
asa
guide
to
check
coil

resistance
.
Make
checks
at
each
harness
connector
.

"
On
M44
engine,
use
Table,c
as
a
guide
to
check
coil
primary
resistance
.

5
.
Inspect
coil
housing
for
hairline
cracks
or
leaking
cast-
ing
material
.
See
Fig
.
7
.
A
leaky
ignition
coil
may
indi-



11502

cate
a
faulty
ECM
(engine
control
module)
.
Check
the
ECM
before
installing
a
new
coil
.



Fig
.
6
.



Ignition
coil
harnessconnector
terminal
identification
for
6-
cylinder
engine
.

IGNITION
SYSTEM
SERVICE

11502

Terminals
Resistance
(refer
to
Fig
.
4
.)

Coil
primary



1
(-)
and
15
(+)



10
.4-0
.8
ohms

Coil
secondary



N
.A
.



N
.A
.

Table
c
.
Ignition
Coil
Resistance

(M44
Engine)

Terminais
Resistance
(referto
Fig
.
5
.)

Coil
#1
primary



1
(-)
and
2
(+)



0
.4-0
.8
ohms

Coil
#2
primary



6
(-)
and2
(+)



0
.4-0
.8
ohms

Coil
#3
primary



7
(-)
and
2
(+)



0
.4-0
.8
ohms

Coil
#4
primary



5
(-)
and2
(+)



0
.4-0
.8
ohms

Coil
secondary



N
.A
.



N
.A
.

NOTE-

If
a
single
coilís
faulty
on
M44
engines,
the
complete
coil
pack
will
have
to
be
replaced
.

Ignition
coil,
testing
and
replacing

(6-cylinder
engine)

CAUTION-

Use
a
digital
multimeter
for
the
following
tests
.

1.
Remove
plastic
enginecovers
from
top
of
engine
by

prying
off
nut
covers
and
removingcover
mounting

nuts
.
See
113
Cylinder
HeadRemoval
and
Installa-

tion
.

2
.
Disconnect
harnessconnectorfromcof
.
Connect
mul-
timeter
between
terminal
15
(+)
in
connector
and

ground
.
See
Fig
.
6
.

3
.
Turn
ignition
on
and
check
for
batteryvoltage
.

"
If
batteryvoltage
is
not
present,
check
wire
between

terminal
15
and
ignition
switch
.
See
Electrical
Wiring

Diagrams
.

"mozo

ELECTRICAL
CHECKS
AND
COMPONENT
TESTING

Main
relay,
testing

The
main
relay
is
energized
via
the
engine
control
module

and
supplies
plus
(+)
power
to
the
many
of
the
engine
man-

agement
components
and
subsystems,
including
the
fuel

pump
relay
.
If
this
relay
is
faulty,
the
engine
will
not
start
.

1
.
With
ignition
off,
remove
main
relay
.
See
Fig
.
6
.

.

iommooommmoi



~
"""

Fuel
DME
sensor

CA
UTION-

Relay
positions
can
vary
.
Be
sure
to
confirm
relay
position
by
identífyíng
the
wiring
in
the
socket
us-
ingthe
wiring
diagramsfound
at
the
rearof
this

manual
.

0013034)
Fuel
pump
relay,
testing

FUEL
INJECTION



130-
7

87

851186

30
~j

1
.
Remove
fuel
pump
relay
from
its
socket
.

87661

Fig
.
7
.



Check
for
battery
voltage
at
main
relay
terminals
30
and
86
.
Voltage
should
be
present
at
all
times
.

4
.
With
ignition
on
and
relay
installed,
check
for
battery

voltage
at
terminals
87
.

"
If
battery
voltage
is
present,relay
has
energized
and
is

functioningcorrectly
.

"
lf
battery
voltage
is
not
present
and
al¡
earlier
tests
are

OK,
relay
is
faulty
and
should
be
replaced
.

Fig
.
6
.



Engine
management
relays
in
the
power
distribution
box,
left
rear
of
engine
compartment
.



The
fuel
pump
relay
is
located
in
the
power
distribution
box
.

Refer
to
Fig
.
6
.

The
ECM
supplies
power
to
the
coil
side
of
the
fuel
pump
re-

lay
.
During
starting,
the
fuel
pump
runs
as
long
as
the
ignition

switch
isin
the
start
position
and
continues
to
run
once
theen-

gine
starts
.
If
the
relay
ís
faulty
the
fuel
pump
will
notrun
.

2
.
Check
for
voltage
at
terminal
30
and
terminal
86
of
re-

¡ay
socket
.
See
Fig
.
7
.



2
.
With
key
off,
check
for
batteryvoltage
at
socket
terminal

"
If
battery
voltage
is
present
continue
testing



30
.
See
Fig
.
8
.

"
lf
battery
voltage
is
not
present
at
either
point,
check

large
red
wire
in
relay
socket
.
See
Electrical
Wiring



3
.
With
ignition
key
in
start
position
check
for
battery
volt-

Diagrams
.



age
at
terminal
86
.

NOTE-



4
.
With
ignition
key,
use
digital
multimeter
to
check
for

The
wiring
to
terminals
85
and
86
in
the
main
relay
may



ground
at
terminal
85
.

be
reversed
.
Electrically,
the
relay
functions
either
way
.

lf
voltage
ís
not
present
at
terminal
86,
check
for
volt-



NOTE-
age
at
terminal
85
.



The
ground
atterminal
85
is
switched
by
the
ECM
.
The

ECM
hamess
must
be
connected
to
check
the

3
.
Reinstall
relay
and
turn
ignition
on
.
Gainaccess
to
un-



switched
ground
connection
.

derside
of
relay
socket
and
check
for
ground
at
terminal

85
(brown
wire)
.



5
.
If
no
faults
are
found
up
tothis
point,
testfuel
pump
op-

"
lf
ground
is
present
continue
testing
.



eration
as
described
in
160
Fuel
Tank
and
Fuel
Pump
.

"
If
ground
is
not
present,
signal
from
ECM
is
missing
.

Check
wire
between
ECM
and
relay
.
If
no
faults
can

be
found,
ECM
may
be
faulty
.

ELECTRICAL
CHECKS
AND
COMPONENT
TESTING

0013ZIM
Fig
.
42
.
Engine
control
module
(ECM)
located
in
compartment
in
right-rearof
engine
compartment
(arrow)
.

NOTE-

Replacement
ECMs
must
be
coded
with
application
in-
formation
(Le
.
engine
code,
transmission
type,
etc
.)
pri-
or
to
installation
.
Consult
an
authorized
BMW
dealer
before
replacing
the
ECM
.

ECM
pin
assignments
are
given
in
Tables
h
through
Table
I.
This
information
can
be
helpful
when
diagnosing
faultsto
or
from
the
ECM
.
If
al¡
inputs
and
wiring
are
OK
butoperational
problems
still
exist,
the
ECM
itself
may
be
faulty
.

Fig
.
43
.
ECM
pin
numbers
as
seen
from
back
of
ECM
connector
.

FUEL
INJECTION



130-
2
7

Generally,
absence
of
voltage
or
continuity
means
there
is
a
wiring
or
connector
problem
.
Test
results
with
incorrect
values
do
notnecessarily
mean
that
a
component
is
faulty
:
Check
for
loose,
broken
or
corroded
connections
and
wiring
before
re-
placing
components
.
If
the
results
are
still
incorrect,
test
the
component
itself
.
For
engine
management
system
electrical
schematics,
see
Electrical
Wiring
Diagrams
.

CAUTION-

Always
waitat
least
40
seconds
after
tuniing
off
the
ignition
before
removing
the
connector
from
the
engine
control
module
(ECM)
.
If
the
connec-
tor
is
removed
before
this
time,
residual
power
in
the
system
relay
may
damage
the
ECM
.

"
Always
connector
disconnect
the
control
module
connector
and
meter
probes
with
the
ignitionoff
.

When
making
checks
at
the
ECM
itself,
a
breakout
box
should
be
used
to
allow
tests
to
be
made
with
the
connector
attached
to
the
ECM
.
This
also
prevents
damage
tothe
small
termínals
in
the
connector
.
As
an
alternative,
theharness
con-
nector
housing
can
be
separated
so
that
electrical
checks
can
be
made
from
the
back
of
the
connector
.
ECM
pin
numbering
is
shown
in
Fig
.
43
.

NOTE
-

On
cars
with
tractioncontrol,
do
not
confuse
the
throttle
position
sensor
on
the
main
throttle
body
with
the
throt-
tle
position
switch
on
the
secondary
throttle
body
.

27
Lb
2L4
LJ
22
©©®®17
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®®®®®®®®®®®®®®®IZA®®®®®®®®®®®®®®®®®

1
>I-
0013211

ECM
PIN
ASSIGNMENTS

NOTE-

Some
cars
covered
by
this
manual
may
have
an
alter-
nate
cooling
fan
switchwith
switching
temperatures
of
176%190W
(80%88°C)
.
When
replacing
the
switch
check
theswitching
specifications,
whichshouldbe
stamped
on
the
switch
body
.

1
.
If
coolant
is
circulating
at
normal
operating
tempera-
ture,
but
auxiliary
cooling
fan
does
not
run,
disconnect
connector
from
radiator
temperature
switch
and
make
tests
listed
in
Table
c
.

Table
c
.
Auxiliary
Cooling
Fan
Temperature

Switch
Tests

Wires
jumpered



Test



Test
resuits
conditions

Black/green
(terminal2)
and



Ignition
ON



Fan
runs
on
brown
(terminal
1)



low
speed

Black/gray
(terminal
3)
and



Ignition
ON



Fan
runson
brown
(terminal



I
1)



high
speed
2
.
If
fan
runs
only
when
powered
directly
by
jumpered
connector
and
hot
coolant
is
circulating
through
radia-
tor,
radiator
temperature
switch
is
most
likelyfaulty
.
Use
a
new
sealing
ring
when
replacing
switch

Tightening
Torque

"
Temperature
switch
to
radiator
......
15
Nm
(11
ft-Ib)

3
.
If
auxiliary
fan
does
notrun
when
powered
directly,
check
for
battery
voltage
at
temperature
switch
connec-
tor
(black/green
wire)
with
ignition
on
.
If
battery
voltage
is
not
present,
check
fuses
.
See
610
Electrical
Com-
ponent
Locations
.

RADIATOR
AND
COOLING
SYSTEM



170-
5

~r~nmm
a
00
0

Fig
.
4
.



Auxiliary
radiator
cooling
fan
low
speed
relay
(1)
and
high
speed
relay
(2)
in
power
distribution
box
.
(Relay
locations
may
vary
.)

Auxiliary
Cooling
Fan
Circuit
Fuses



Fig
.
5
.
Auxiliary
radiator
fan
resistor
(arrow)
.
"
Fuse16
.
...................
..
..
...
...
.5
amp

"
Fuse
41
(ex
.
M44
w/man
.
trans)
.
..
.
..
.....
30
amp

"
Fuse
48
(M44
w/man
.
trans
.
only)
..
.
..
.....
40
amp



COOLING
SYSTEM
SERVICE

0013034

4
.
If
no
faults
are
found,
remove
low
speed
relay
and
turn



Coolant,draining
and
filling

ignition
ON
.
See
Fig
.
4
.



1
.
Remove
expansion
tank
cap
.
Set
temperature
controls
"
Check
for
power
at
terminal
30
and
terminal
86
of
relay



to
full
warm
.
socket
.

"
Reinstall
low
speed
relay
and
repeat
testat
high
speed



WARNING
-
relay
socket
.
Fix
any
wiring
faults
found
.



Allow
the
cooling
system
to
cool
before
openlng
or

On
early
productioncars
(up
to
9/92)
:
If
fan
operates
only
on



draining
the
cooling
system
.

high
speed
and
no
electrical
faults
have
been
foundup
to
this
point,
usean
ohmmeter
to
check
that
fan
resistor
is
not
electri-



2
.
Place
3
ra
allo

ug
.



beneath
radiator
drain
plug
and
re-

cally
open
.
Resistor
is
mounted
on
auxiliary
cooling
fan
housing



move
drain
plg
.
See
Fig
.
6
.

behind
front
grille
.
See
Fig
.
5
.
Wiring
diagrams
for
the
radiator

cooling
fan
canbefoundunder
Electrical
Wiring
Diagrams
.



3
.
Place
3-g



pail
beneath
rear
of
engine
blo
.
Loos-
en
and
re

mlon

ove
engine
blockcoolant
drain
plug
k
.

COOLING
SYSTEM
SERVICE

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

600-2



ELECTRICAL
SYSTEM-GENERAL

CAUTION
-

"
Always
turn
off
the
engine
and
disconnect
the

negative
()
cable
from
the
batterybefore
remov-

ing
any
electrical
components
.
Disconnecting
the

battery
may
erase
fault
code(s)
stored
in
control

module
memory
.
Check
for
fault
codes
using
spe-
cial
BMW
diagnostic
equipment
.

"
Prior
to
disconnecting
the
battery,
read
the
bat-

tery
disconnection
cautions
given
at
the
front
of

this
manual
onpage
viii
.

"
Connect
and
disconnect
ignition
system
wires,
multiple
connectors,
and
ignition
test
equipment
leads
only
while
the
ignition
is
off
.

"
Do
not
disconnect
the
battery
with
engine
run-

ning
.

"
Do
not
quick-charge
the
battery
(for
boost
start-
ing)
for
longer
than
one
minute,
and
do
not
ex-
ceed
16
.5
volts
at
the
battery
with
the
boosting
cables
attached
.
Wait
at
feast
one
minute
before
boosting
the
battery
a
second
time
.

"
Do
not
usea
test
famp
that
has
a
normal
incan-

descent
bulb
to
test
circuits
contafning
electronic
components
.
The
high
electrical
consumptionof
these
test
lamps
may
damage
the
components
.

"
Do
not
use
an
analog
meter
.
Use
onfy
a
digital
multimeter
.

"
Many
of
the
solid-state
modules
are
static
sensi-
tive
.
Static
discharge
will
permanently
damage
them
.
Always
handle
the
modules
using
proper
static
prevention
equipment
and
techniques
.

"
To
avoid
damaging
harness
connectors
or
relay
panel
sockets,
use
jumper
wires
with
flat-blade
connectors
that
are
the
same
size
as
the
connec-
tor
or
relay
terminals
.

"
Always
switch
a
digital
multimeter
to
the
appropri-
ate
function
and
range
before
making
test
con-
nections
.

"
Do
not
tryto
start
the
engine
of
a
carwhich
has
been
heated
above176°F
(80°C),
(for
example,
in
a
paint
dryingbooth)
.
Allow
it
to
cool
to
normal
temperature
.

"
Disconnect
the
battery
before
dolng
any
electric
welding
on
the
car
.

"
Do
not
wash
the
engine
while
it
is
runnfng,
or
any-
time
the
ignition
is
switched
on
.

WIRING
DIAGRAMS

Electrical
Test
Equipment

Many
of
the
electrical
tests
described
in
this
manual
call
for

measuring
voltage,
currentorresistanceusing
a
digital
multi-

meter
(DMM)
.
Digital
meters
are
preferred
for
precise
mea-

surements
and
for
electronics
work
because
they
are
generally
more
accuratethan
analog
meters
.
The
numerical

display
is
alsoless
likely
to
be
misread,
since
there
is
no
nee-

dle
position
to
be
misinterpreted
by
reading
at
an
angle
.

An
LED
test
light
is
a
safe,
inexpensive
tool
that
can
be
used

to
perform
many
simple
electrical
tests
that
would
otherwise

require
a
digital
multimeter
.
The
LED
indicates
when
voltage

is
present
between
anytwo
test-points
in
a
circuit
.

CA
UTION-

"
Choose
test
equipment
carefully
.
Use
a
digital

multimeter
with
at
leadt
10
megaohm
input
im-

pedance,or
an
LED
test
light
.
An
analog
meter
(swing-need1e)
ora
test
light
with
a
normal
incan-
descent
bulb
may
draw
enough
current
to
dam-
age
sensitive
electronic
components
.

"
An
ohmmeter
must
not
beused
to
measure
resis-
tance
on
solidstate
components
suchas
controlunits
or
time
delay
relays
.

"
Always
disconnect
the
battery
before
making
re-

sístance
(ohm)
measurements
on
the
circuit
.

WIRING
DIAGRAMS

The
wiring
diagrams
shown
in
Electrical
Wiring
Diagrams

have
been
specially
designed
to
enable
quick
and
efficientdi-

agnosis
and
troubleshooting
of
electrical
malfunctions
.

Wiring
Codes
and
Abbreviations

A
lot
of
information
is
included
in
each
wiring
diagram
if
you
know
how
to
read
them
.
Wire
colors
in
the
diagrams
are
ab-

breviated
.
Combined
color
codes
indicate
a
multi-colored
wire
.
For
example
the
code
BLU/RED
indicates
a
Blue
wire

with
a
Red
stripe
.

Many
electrical
components,
connectors,
fuses,
and

ground
locations
are
identified
using
a
unique
number
.
Each

of
there
numbers
corresponds
to
a
particular
part
in
the
circuit
commonly
found
in
Electrical
Wiring
Diagrams
.