1993 BMW 325i Engine wiring

Continuity,
checking
Short
Circuits

from
Battery

CAUTION-

Use
only
a
high
quality
digital
ohmmeter
having
high
input
impedance
when
checking
electronic
componente
.
The
internal
power
source
used
in
most
analog
(swing-need1e)
meterscan
damage
solidstate
components
.

0013239

Fig
.
2
.



Digital
multimeter
being
used
to
check
for
voltage
drop
across
a
switch
.

The
continuity
test
can
beused
to
check
a
circuit
or
switch
.
Because
most
automotive
circuits
are
designed
to
have
little

or
no
resistance,
a
circuit
or
part
of
a
circuit
canbe
easily

checked
for
faults
using
an
ohmmeter
.
An
open
circuit
or
a
cir-

cuit
withhigh
resistance
will
not
allow
current
to
flow
.
A
círcuit
with
little
or
no
resistanceallows
current
to
flow
easily
.

When
checking
continuity,
the
ignition
should
be
off
.
On
cir-
cuits
that
are
powered
at
all
times,
the
battery
should
be
dis-
connected
.
Using
the
appropriate
wiring
diagram,
a
circuit
can
be
easily
tested
for
faulty
connections,
wires,
switches,
relays,
and
engine
sensorsby
checking
forcontinuity
.
For
a
continu-
ity
check
on
a
brake
light
switch,
see
Fig
.
3
..

A
short
circuit
is
exactly
what
the
narre
implies
.
The
circuit
takes
a
shorter
paththan
it
was
designed
to
take
.
The
most

common
short
that
causes
problems
is
a
short
to
ground

where
the
insulation
on
a
positive
(+)
wire
wears
away
and
the

metal
wire
is
exposed
.
When
the
wire
rubs
against
a
metal

partof
thecar
or
other
ground
source,
the
circuit
is
shorted
to
ground
.
If
the
exposed
wire
is
live
(positive
battery
voltage),
a

Puse
will
blow
and
the
circuit
may
possibly
be
damaged
.

ELECTRICAL
SYSTEM
-
GENERAL
600-
5

Brake
light
switch

Brake
pedal
in
rest
position

Q

Brake
pedal
depressed
Brake
light
switch

Fig
.
3
.



Brake
light
switchbeing
tested
for
continuity
.
With
brake
ped-
alin
rest
position
(switch
open)
there
is
no
continuity
(infinite
ohms)
.
With
pedal
depressed
(switch
closed)
there
is
continu-
ity
(zero
ohms)
.

Shorts
to
groundcanbe
located
with
a
digital
multimeter
.
Short
circuits
are
often
difficult
to
locate
and
may
vary
in
na-
ture
.
Short
circuits
can
befound
using
a
logical
approach
based
onthe
current
path
.

CAUTION
-

"
On
circuits
protected
with
high
rating
fuses
(25
amp
and
greater),
the
wires
or
circuit
compo-
nents
may
be
damaged
before
the
fuse
blows
.
Always
check
for
damage
before
replacing
fuses
of
this
rating
.

"
When
replacing
blown
fuses,
use
only
fuses
hav-
ingthe
correct
rating
.
Always
confirm
the
correct
fuse
rating
printed
on
the
fuselrelay
panelcover

DC

ELECTRICAL
TROUBLESHOOTING

611-
4



WIPERS
AND
WASHERS

2
.
Remove
wiper
arms
as
described
earlier
.

3
.
Place
engine
hood
in
service
position
.
See
410
Fend-

ers,
Engine
Hood
.

4
.
Unclip
engine
bulkhead
plenum
grille
at
base
of
wind-

shield
and
pulí
it
away
from
rubbergasket
.
See
Fig
.
5
.

Fig
.
5
.



Detach
grill
clips
(arrows)
and
pull
upward
.

0012527

5
.
Remove
wiring
harness
retaining
clip
frombulkhead
in
rear
of
engine
bay
.
Remove
screws
retaining
wiring
harness
protective
cover
.
See
Fig
.
6
.

0012529

Fig
.
6
.



Engine
bulkhead
wiring
harness
cover
screws
(arrows)
.

WINDSHIELD
WIPER
ASSEMBLY

Fig
.
7
.



Right
side
plenum
retaining
screws
(arrows)
.

7
.
On
driver's
side
of
air
plenum,
push
aside
wiring
har-

ness
and
remove
screw
retaining
plenum
.
Pull
plenum

up
andremove
from
engine
compartment
.
See
Fig
.
8
.

001¿534

Fig
.
8
.



Remove
screw
at
A
and
pull
plenum
housing
upward
.

8
.
On
6-cylinder
models
:
Remove
plastic
top
engine
cov-
ers
.
See
110Engine
Removal
and
Installation
.

NOTE-

Cover
ínside
edges
of
cowlpanelsheet
metal
with
thick
tape
to
prevent
damage
during
wiper
assembly
remov-
al
.

9
.
Remove
large
nut
and
washer
at
base
of
wiper
arm

shafts
cowi
panel
.
See
Fig
.
9
.

10
.
Remove
wiper
assembly
support
.
See
Fig
.
10
.

6
.
On
passenger
side
of
air
plenum,
push
aside
wiring



11
.
Separateharness
at
bulkhead
connector
.
See
Fig
.
11
.

harness
and
remove
twoscrews
retaining
plenum
housing
.
See
Fig
.
7
.



12
.
Wrap
protective
tape
around
wiper
shaft
on
driver's
side
to
prevent
damaging
painted
metal
during
remov-
al
.

Fig
.
9
.



Wiper
shaft
nut
at
cowl
(arrow)
.

Fig
.
10
.
Wiper
assembly
support
bolts
(arrows)
.

0012533
0012535

Fig
.
11
.
Wiper
assembly
electrical
connector
(arrow)
.

0012536

13
.
Push
wiper
arm
shaft
down
into
cowl
area
and
maneu-

ver
wiper
assembly
out
of
cowl
.

WIPERS
AND
WASHERS



611-
5

14
.
Installation
is
reverse
of
removal,noting
the
following
:

"
Install
all
fasteners
finger-tight
first
.

"
Once
installed,
wiper
motor
should
first
be
run
to

parked
position
and
switched
off
.

"
Next,
instaf
wiper
arms
butnotblades
.

"
Close
hood
and
fit
wiper
blades
.

"
Check
all
electrical
harness
fittings
and
sealing
grom-

mets
for
correct
reinstallation
.
Replace
any
wire
ties

cut
off
during
removal
.

Tightening
Torques

"
Wiper
shaft
nut
at
cowl
.............
12
Nm
(9
ft-Ib)

"
Wiper
support
to
wiper
assembly

orto
body
..
..
..
.
...............
10
Nm
(89
in-lb)

"
Wiper
arm
to
wiper
shaft
..........
25
Nm
(18
ft-lb)

Windshieldwiper
assembly,
removing
and

installing
(2-door
modeis)

NOTE-

The
wiper
arms
should
be
in
the
parked
position
before
removing
the
wiper
assembly
.
To
avoid
damaging
the
wiper
arms
and
pivots,
donotmanually
sidde
or
force
the
wiper
arm
across
the
windshield
.

1
.
Disconnect
negative
(-)cablefrom
battery
.

CAUTION-

"
Prior
to
disconnectiog
the
battery,
read
the
bat-
tery
disconnection
cautionsgiven
at
the
front
of
this
manual
on
page
viii
.

"
Use
fendercover
to
protect
windshield
.

2
.
Remove
wiper
arms
as
described
earlier
.

3
.
Place
engine
hood
in
service
position
.
See410
Fend-

ers,
Engine
Hood
.

4
.
Remove
trim
retainers
at
left
and
right
side
and
remove

air
plenum
grill
.
See
Fig
.
12
.

5
.
Remove
screws
retaining
wiring
harness
protective

cover
.
See
Fig
.
13
.

6
.
On
passenger
side
of
air
plenum,push
aside
wiring

harness
and
remove
two
screws
retaining
plenum

housing
.
See
Fig
.
14
.

WINDSHIELD
WIPER
ASSEMBLY

611-
6



WIPERS
AND
WASHERS

Fig
.
12
.
Left
side
air
plenum
grill
trim
retainers
(arrows)
.

uu12529
Fig
.
13
.
Engine
bulkhead
wiring
harness
cover
screws
(arrows)
.

WINDSHIELD
WIPER
ASSEMBLY

Fig
.
15
.
Remove
screw
at
A
and
pull
plenum
upward
.

0012635

Fig
.
14
.
Right
side
plenum
retaining
screws
(black
arrows)
.
Note
positive
leads
to
main
(+)
connector
(white
arrow)
.

7
.
On
driver's
side
of
air
plenum,
push
aside
wiring
har-

ness
and
remove
screw
retaining
pienum
.
Pull
plenum

up
and
remove
from
engine
bay
.
See
Fig
.
15
.

8
.
On
passenger
side
of
engine
compartment
bulkhead,

remove
engine
control
module
(ECM)
compartment

cover
.
See
Fig
.
16
.

9
.
Disconnectharness
connector(s)
from
ECM
and
auto-
matic
transmission
control
module
(if
applicable)
.
Care-
fully
pull
harness
and
wire
loomas
far
forward
as
possible
.
If
necessary,disconnect
positive
leads
at
main
(+)
connector
.

10
.
Remove
wiper
assembly
mounting
fasteners
.
See
Fig
.
17
.

640-2



HEATING
AND
AIR
CONDITIONING

3
.
Remove
wiring
harness
retaining
clip
at
bulkhead
.
Re-

move
screws
retaining
wiring
harness
cover
and
pull

cover
forward
.
See
Fig
.
2
.

0012529

Fig
.
2
.
Ming
harness
cover
screws
at
base
ofwindshield
(arrows)
.

4
.
On
passenger
side,
push
aside
wiring
harness
and
re-

move
two
screws
retaining
plenum
housing
.
See
Fig
.
3
.

Fig
.
3
.



Ríghtside
plenum
retaining
screws
(arrows)
.

VU1L535

5
.
On
driverside,
push
aside
wiring
harness
and
remove

screw
retaining
plenum
.
Pull
plenum
up
and
remove
from
engine
bay
.
See
Fig
.
4
.

6
.
Unclip
blower
motor
housing
cover,
disconnect
control

cable,
and
turn
center
retainer
1
/4
turn
to
remove
cover
.
See
Fig
.
5
.

7
.
Disconnect
electrical
connectors
from
blower
motor
.

8
.
Remove
left
upper
section
of
blower
housingby
detach-
ing
spring
clipsat
edge
of
housing
.
See
Fig
.
6
.

HEATER
AND
CONTROLS

Fig
.
4
.



Remove
screw
at
A
and
pull
air
plenumupward
.

0012534

0012636

Fig
.
5
.



Blower
motor
housing
clips
(A)
;
control
cable
(B)
;
and
center
retainer(C)
.

i
[u6,

Fig
.
6
.



Spring
clips
(arrows)
on
driver
sideof
blower
housing
.

640-4



HEATING
AND
AIR
CONDITIONING

Heater
box,
removing
and
installing

The
heater
box,
located
underneath
thecenter
of
the
dash-

board,
houses
theheater
core,
the
A/C
evaporator,
and
asso-

ciated
sensors
and
actuators
.
Removal
of
theheater
box

requires
that
the
A/C
refrigerant
be
discharged
.

CAUTION-

"
Removing
the
heater
box
requires
evacuating
the
AIC
system
.
DO
NOT
attempt
this
procedure
without
proper
tools
and
training
.

"
Any
person
who
services
a
motor
vehicle
air
con-

ditioner
must,
by
law,
be
properly
trained
and
cer-
tified,
and
use
approved
refrigerant
recycling
equipment
.
Technicians
must
complete
an
EPA-
approved
recycling
course
to
be
certified
UU12639

Fig
.
10
.
Heater
core
mounting
nuts
at
left
sideof
bulkhead
(arrow)
.

1
.
Drain
engine
coolant
.
See
170
Radiator
and
Cooling



wiper
assembly
shown
removed
for
clarity
.

System
.

2
.
Remove
complete
dashboard
.
See513
Interior
Trim
.

3
.
Remove
blower
motoras
described
earlier
.

4
.
Remove
nut
retaining
water
hose
flange
to
rear
bulk-
head
.
I'ush
flange
to
one
side
.
See
Fig
.
9
.

Fig
.
9
.



Nut
retaining
coolant
hose
flangeat
bulkhead
(arrow)
.

NOTE-

Clear
any
remaining
coolant
from
the
heater
core
by
blowing
compressed
air
finto
the
coolant
feed
hose
.

HEATER
AND
CONTROLS

0012638b

6
.
Cut
wire
tie
holding
wire
harness
to
heater
box
and
dis-

connect
cable
harness
connector
from
heater
box
.
See

Fig
.
11
.

0012647

Fig
.
11
.
Harness
connectors
(A)
and
cable
tie
(B)
at
heaterbox,
under
driver
side
dash
.

7
.
Followingmanufacturer's
instructions,
connect
ap-

proved
refrigerant
recovery/recycling/recharging
unitto

A/C
system
and
discharge
system
.

8
.
Unbolt
A/C
refrigerantlines
flange
from
engine
bay
bulkhead
.
See
Fig
.
12
.

9
.
On
models
with
rotary-knob
A/C
control
head
:
Discon-
5
.
Remove
nuts
from
heater
box
retaining
bracket
on
en-



nect
wiring
harness
connectors
to
A/C
control
module
gine
bulkhead
left
side
.
See
Fig
.
10
.
Repeat
procedure



in
center
console
and
remove
module
.
See
Fig
.
13
.
for
right
side
nuts
.

640-10



HEATING
AND
AIR
CONDITIONING

i

El
Radio

Antenna

Rear



.
,



si,-
Left
side



I
d

1
.
Rear
vents
2
.
Fresh
air
3
.
Face-level
vents
4
.
Recirculation
5
.
Footwell
vents
0013017

Fig
.
28
.
Location
oflate
production
air
distribution
motors
in
heater
box(shown
in
rear,
side
and
top
views)
.

Heater
andA/C
air
distribution
motor,

replacing
(rotary-knob)

1
.
Toaccess
left
side
motors
(dash
vent
mixing
or
recircu-

lation
flap),
remove
lower
dash
panel
and
knee
bolster

on
driver
side
.
See
513
Interior
Trim
.

2
.
To
access
right
side
motor
(fresh
air
flap),
remove
glove

compartment
.
See513
Interior
Trim
.

3
.
Each
motor
can
be
removed
after
its
electrical
wiring

harness
connector
has
been
removed
.
Squeeze
plastic

clip
to
release
motor
.
See
Fig
.
29
.

Fig
.
29
.
A/
C
air
distribution
motor
plastic
retaíning
clip
(arrow)
.
Re-
lease
clip
and
tilt
motor
out
of
housing
.

Rear
Window
Defogger

0011877

The
rear
window
defogger
switch
is
integrated
with
the
heating
andA/C
control
head
.

HEATER
AND
CONTROLS

Fig
.
30
.
Wiring
diagram
of
rear
window
defogger
and
radio
antenna
.

Rear
Window
Blower
(Convertible
Models)

A
blower
fan,
fitted
into
the
rear
seatback,
defogs
therear

window
.
It
will
only
operate
with
the
engine
nunning
and
the

top
raised
.
A
microswitch
behindthe
rear
seats
provides
the

signal
that
thetop
is
raised
.

To
access
the
blower
fan
motor,
it
is
necessary
to
remove

four
screwsfrom
the
center
seat
back
.
Remove
the
wiring
har-

ness
connector
and
motor
mounting
boits,
then
remove
motor

by
pulling
it
down
and
forward
.
See
Fig
.
31
.

ri

Suppressor
filter

1
0013005

Fig
.
31
.
Rear
window
blower
in
center
of
rear
seat
back
(arrow)
.

The
electric
rear
window
defogger
is
integrated
with
the
ra-

dio
antenna
.
See
Fig
.
30
.



y



/f



0013014

721-
6



AIRBAG
SYSTEM
(SRS)

5
.
Carefully
lift
airbag
unit
off
steering
wheel
and
discon-



6
.
Installation
is
reverse
of
removal
.
Tighten
right
side
nect
orange
harness
connector
from
rear
of
airbag
unit
.



screw
on
airbag
first
(as
viewedfrom
driver's
seat),

See
Fig
.
10
.



then
left
side
screw
.

NOTE-



NOTE-

In
some
models,
theairbag
electrical
connection
to
the



If
there
is
no
electrical
harness
connector
between
the
steering
wheel
isvia
aplug
in
back
of
the
airbag
unit
.



airbag
and
the
steering
wheel,
be
sure
to
fit
the
push
There
is
no
wire
harness
to
disconnect
.



in
electrical
plug
in
back
of
the
airbag
finto
the
proper
re-
ceptacle
in
the
steering
wheel
.

Fig
.
10
.
Driver
sideairbag
unit
harness
connector
(arrow)
.

AIRBAGS

WARNING
-

"
Store
the
removed
airbag
unit
with
the
horn
pad
facing
up
.
If
stored
facing
down,
accidental
de-
ployment
couldpropel
it
violently
into
the
air,
causing
injury
.

"
Once
an
airbag
is
removed,
the
car
must
not
be
driven
.

"
Do
not
connect
the
battery
with
the
airbag
dis-
connected
.
A
fault
code
will
be
stored,
setting
off
the
SRS
warning
light
.
Special
tools
are
needed
to
reset
the
fault
memory
.

"
Special
instructions
apply
when
installing
an
air-
bag
equipped
steering
wheel
.
See
320
Steering
and
Wheel
Alignment
.

"
Once
the
airbag
unit
is
installnd
and
all
other
ser-vice
procedureshave
been
completed,
start
the
engíne
and
check
that
the
SRS
warning
light
goes
out
.
If
the
warning
light
stays
on,
the
SRS
system
will
not
function
as
designed
.
Have
the
system
diagnosed
and
repaired
by
an
authorized
BMW
dealer
.

0013184

Tightening
Torque

"
Airbag
unitto
steering
wheel
........
8
Nm
(71
in-lb)

Passenger
side
airbag,

removing
and
installing

1
.
Disconnect
negative
(-)
cable
from
battery
and
cover
negative
terminal
with
insulating
material
.

2
.
Remove
glove
compartment
.
See
513
Interior
Trim
.

3
.
Lift
cover
from
topof
passenger
sideairbag
on
dash-
board
.
See
Fig
.
11
.

0013108
Fig
.
11
.
After
removing
glove
compartment,
lift
out
passenger
side
air-
bag
cover
.
Note
airbag
mounting
bolts
(A)
and
airbag
electri-
cal
connector
(B)
.

4
.
Remove
passenger
sideairbag
mounting
bolts
.
Dis-
connect
electrical
harness
connector
from
rear
of
air-
bag
unit
and
remove
airbag
.

5
.
Installation
is
reverse
of
removal
.
Make
sure
wiring
har-
ness
is
not
pínched
when
installing
airbag
unit
in
dash-board
.