1994 BMW 325i electrical

Fig
.
36
.
BMW
special
tool
no
.
11
2
300
installed
through
bellhousing
and
finto
flywheel
.

8
.
Remove
oil
line
fitting
from
VANOS
control
unit
.

NOTE-

Wrap
the
VANOS
oil
line
fitting
with
a
shop
to
absorb
leaking
oil
.

9
.
Using
hollow
bolt
and
seals
from
oil
supply
line,
instan

BMW
special
tool
no
.
11
3
450
(air
line
fitting)
and
con-
nect
a
supply
of
compressed
air
(30-115
psi)
to
VANOS

oil
fitting
.

10
.
Measure
and
record
distance
between
trigger
plate

edge
and
side
of
secondary
timing
chain
tensioner
.

See
Fig
.
37
.

Fig
.
37
.
VANOS
reference
measurement
(dimension
A)
between
trig-
ger
píate
(sender
gear)
and
side
of
secondary
chain
tensioner
.

CAMSHAFT
TIMING
CHAIN



117-
1
5

11
.
Disconnectharness
connector
from
VANOS
solenoid
.
Connect
BMW
special
tool
no
.
12
6
410
(electrical
test
lead)
to
VANOS
solenoid
connector
.

"
Connect
positive
(+)
test
lead
to
positive
(+)
terminal
ofbattery
Connect
negative
(-)
test
leadto
chassis
ground
.
solenoid
should
audibly
click
and
intake
cam-
shaft
should
advance
.

CA
UTION-

"
Be
sure
to
connect
the
test
hamess
polaritycor-
rectly
.
lf
the
polarity
is
reversed,
the
intemal
diode
in
the
VANOS
solenoid
will
be
destroyed
.
Although
the
solenoid
will
still
functionwith
a
faultydiode,
a
fault
code
may
be
set
in
the
ECM
memory
.

"
To
confirm
voltage
polarity,
turn
the
ignition
on
and
check
for
positive
(+)
batteryvoltage
at
the
terminal
corresponding
to
the
redlwhite
wire
in
the
main
harness
connector
.
Check
that
the
pos-
itive
terminal
(+)
in
the
main
connector
corre-
sponds
to
the
same
terminal
in
the
solenoid
connector
that
is
being
connected
to
the
battery
.

12
.
With
solenoid
actuated,
measure
and
record
new
dis-

tance
between
trigger
plate
edge
and
side'of
second-
ary
timing
chain
tensioner,
as
shown
in
Fig
.
37
.

13
.
Difference
between
first
measurement
(step
10)
andsecond
measurement
(step12)
should
be
at
least
8
.5
mm
(0
.3346
in
.)
.
lf
any
faults
arefound,
solenoid
may

be
faulty,
or
hydraulic
control
unit
may
be
faulty
or
incor-
rectly
installed
.

14
.
Check
VANOS
solenoid
byremoving
it
from
control
unit
.
Check
that
solenoid
plunger
and
control
unit

plunger
move
freely
.
Install
solenoid
using
tighteníng

torque
given
below
.

NOTE-

"
The
solenoid
is
available
asareplacement
part
.
lf
the
control
unit
plunger
is
sticking,
the
complete
control
unit
will
have
to
be
replaced
.

"lf
the
VANOS
system
does
not
advance
correctly
and
no
other
faults
can
be
found,
itis
possible
that
the
VANOS
control
unit
may
Nave
been
fnstalled
incor-
rectly-especially
if
the
camshaft
sprockets
have
pre-
víously
been
removed
for
other
repairs
.
Check
the
installation
by
removing
and
reinstalling
the
control
unit
as
described
later
.

VANOS
(VARIABLE
VALVE
TIMING)

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
.

120-2



IGNITION
SYSTEM

Fig
.1
.



Ignition
characteristic
map
.

Disabling
Ignition
System

WARNING
-

The
ignition
system
is
a
high-energy
system
operat-
ing
in
a
dangerous
voltage
range
that
couldprove
to
be
fatal
if
exposed
terminals
or
live
parts
are
con-
tacted
.
Use
extreme
caution
when
working
on
a
car
with
the
ignition
on
or
the
engine
running
.

The
ignition
system
operates
in
a
lethal
voltage
range
and
should
therefore
be
disabied
any
time
senrice
or
repair
work
is
being
doneon
the
engine
that
requires
the
ignition
to
be
switched
on
.

The
engine
management
system
can
be
disabled
byremov-
ingthe
main
relay
.
The
relay
is
located
in
the
power
distribution
box
in
the
left
rear
of
the
engine
compartment
.
See
Fig
.
2
.

0013134
Fig
.
2
.



Maínsystem
relay
(arrow)
in
power
distribution
box
(left
rear
of
engine
compartment)
.

GENERAL

WARNING
-

"
Do
not
touch
or
disconnect
any
of
the
high
ten-
sion
cables
at
the
cotls
orspark
plugs
while
the
engine
ts
running
orbeingcranked
by
the
starter
.
Fatalvoltages
are
present
.

"
Before
operating
the
starter
without
starting
the
engine
(for
example
when
making
a
compression
test)
always
disable
the
ignition
.

CAUTION-

"
Prior
to
disconnecting
the
battery,
read
the
bat-tery
disconnection
cautions
gtven
at
the
front
of
thts
manual
on
page
viti
.

"
Do
not
attempt
to
disable
the
ignition
by
either
re-
moving
the
cotl
from
the
spark
plugs
(6-cylinder
engines)
or
disconnecting
the
coll
wires
from
the
plugs
(4-cylinder
engines)
.

"
Connect
or
disconnect
ignition
system
wires,
multiple
connectors,
and
ignition
test
equipment
leads
only
while
the
ignitionis
off
.
Switch
multtm-
eter
functions
or
measurement
ranges
onty
with
the
test
probes
disconnected
.

"
Do
not
disconnect
the
battery
while
the
engine
ts
running
.

"
Many
of
the
tests
of
ignition
system
components
require
the
use
of
high-impedance
test
equip-
ment
to
prevent
damage
to
the
electrical
compo-
nents
.
A
high
impedance
digital
multimeter
should
be
used
for
all
voltage
and
resistance
tests
.
AnLED
test
light
shouldbe
used
in
place
of
an
incandescent-type
test
lamp
.

"In
general,
make
test
connections
only
as
speci-fied
by
BMW,
as
described
inthis
manual,
or
as
described
by
the
instrumenta
manufacturer
.

IGNITION
SYSTEM
DIAGNOSTICS



IGNITION
SYSTEM
SERVICE

Poor
driveability
may
have
a
variety
of
causes
.
The
fault



On
4-cylinder
engines,
an
ignition
coil
pack
is
mounted
to

may
lie
with
the
ignition
system,
the
fuel
system,
parts
of
the



the
passenger
side
strut
tower
in
the
engine
compartment
.

emission
control
system,
or
a
combination
of
the
three
.
Be-



The
coil
pack
integrates
4
individual
coils
.

cause
of
these
interrelated
functions
and
their
effects
oneach

other,
it
is
often
difficult
to
know
where
to
begin
looking
for



On
6-cylinder
engines,
an
ignition
coil
is
located
directly

problems
.



above
each
spark
plug
.

For
this
reason,
effective
troubleshooting
should
alwaysbe-

gin
with
an
interrogation
of
the
On-Board
Diagnostic
(OBD)

system
.
The
OBD
system
detects
certain
emissions-related

engine
management
malfunctions
.
When
faults
are
detected,

the
OBD
system
stores
a
Diagnostic
Trouble
Code
(DTC)
in

the
system
ECM
.
In
addition,
the
Check
Enginewarning
light

will
come
on
if
an
emissions-related
fault
is
detected
.

Two
generations
of
OBD
areusedon
the
cars
coveredby

this
manual
.
See
100
Engine-General
for
OBD
information
.

On-Board
Diagnostics

"
1992-1995
models
............
...
.
..
...



OBD
I

"
1996
and
later
models
.........
.......
..
OBD
II

NOTE-

"
On
carswith
OBD
ti,
specialized
OBD
11
scan
tool

equipment
mustbeused
to
access
DTCs,
either
using

the
BMW
special
tool
or
a
`generic"
OBD
11
scan
tool
.

"
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
dísconnecting
the
battery
will
not
erase
the
fault

memory
.

Basic
Troubleshooting
Principies

An
engine
that
starts
and
runs
indicates
the
ignition
system

is
fundamentally
working-delivering
voltage
toat
least
some

of
the
sparkplugs
.
A
hard-starting
or
poor-running
engine,

however,
may
indicate
ignition
coil
problems,
cracked
or
dete-

riorated
spark
plug
wires
(4-cylinder
engines
only),
and
worn

or
fouled
spark
plugs
.

WARNING
-

Inefficient
combustion
(richair/fuel
mixture)
can

cause
the
catalytic
converter
to
overheat
and
plug
.

An
overheated
catalytic
converter
can
also
bea
tire

hazard
.

Checking
for
Spark

IGNITION
SYSTEM



120-
3

WARNING
-

If
a
spark
test
is
done
incorrectly,
damage
to
theen-
gine
control
module
(ECM)
or
the
ignitioncoil(s)
may
result
.

Checking
for
spark
is
difficult
onengines
with
distributorless

ignition
systems
.

Try
Rmovng
the
plugs
and
inspecting
for
differences
be-

tween
them
.
A
poor-firing
plug
may
be
wet
with
fuel
and/or

black
and
sooty,
butnot
always
.
If
a
coil
is
not
operating,
the

engine
management
system
will
electrically
disable
the
fuel
injectorto
that
cylinder
.
The
key
is
to
look
for
differences
be-

tween
cylinders
.

Ignition
coil,
testing
and
replacing

(4-cylinder
engine)

1.
Disconnect
mainharness
connector
from
coils
:

"
On
M42
engine,
remove
plastic
covering
from
coils
and

disconnect
individual
harness
connectors
.

"
On
M44
engine,
disconnect
main
harness
connectorat

end
of
coil
pack
.
See
Fig
.
3
.

Fig
.
3
.



Ignition
coil
pack
for
M44
engine
(arrow)
.
Coil
harness
con-

nector
shown
at1
.

IGNITION
SYSTEM
SERVICE

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

CHARGING
SYSTEM

TROUBLESHOOTING
.............
.
.
.
.
.121-2

Charging
System
Quick-Check
...
.
..
.
...
.
121-2

Static
current
draw,
checking
........
.
...
.
121-2

BATTERY
SERVICE
....................
121-3

Battery
Testing
.
.
.
.
.
.........
.
........
.
121-3

Hydrometer
Testing
.
...
.
.
.
...
.
.........
121-3

Battery
Open-Circuit
Voltage
Test
....
.
....
121-4

Battery
Load
Voltage
Test
.
.
.
.
.
.
.........
121-4

Battery
Charging
.
.
.
.
...
.
.
.
.
.
.
.
.........
121-4

ALTERNATOR
SERVICE
.
.
.
.
.
.
.....
.
...
121-4

Chargingsystem,checking
.
.
.
.
.
.........
121-4

Alternator,
removingand
installing

(4-cylinder
engine)
....
.
.
.
.
.
.
.
.........
121-5

Alternator,
removingand
installing

(6-cylinder
engine)
..
.
.
.
.
.
.
.
.
.
.........
121-6

GENERAL

The
charging
system
consists
of
a
belt-driven
alternator

with
integral
voltage
regulator
and
a
battery
mounted
in
the

luggage
compartment
.

Various
versions
of
alternators,
voltage
regulators,
starters,

and
batteries
are
used
in
the
E36
cars
.
It
is
important
to
re-

place
components
according
tothe
original
equipment
speci-

fication
.
Check
with
an
authorized
BMW
dealer
for
specific

application
and
parts
information
.

WARNING
-

"
Weargoggles,
rubbergloves,
and
a
rubberapron
when
working
around
batteries
and
battery
acid
(electrolyte)
.

"
Battery
acid
contains
sulfuric
acid
and
can
cause
skin
irritation
and
burning
.
ff
acid
is
spilled
onyour
skin
or
clothing,
flush
the
area
at
once
with
large
quantities
of
water
.
lf
electrolyte
gets
into
your
eyes,flush
them
with
largequantities
of
clean
wa-
terfor
several
minutes
and
call
a
physician
.

"
Batteries
that
are
being
charged
or
are
fully
charged
give
off
explosive
hydrogen
gas
.
Keep
sparks
and
open
flames
away
.
Do
not
smoke
.

BATTERY,
STARTER,
ALTERNATOR



121-1

121
Battery,
Starter,
Alternator

GENERAL
..
.
...
.
........
.
...
.
.
.
.
.
.
.
.
.
121-1



Voltage
regulator,
removing
and
ínstalling
.
.
.
121-6

Alternator
brushes,
inspecting
and
replacing
.121-7

STARTER
SERVICE
....
.
.
.
.
.
..........
.121-7

Starter
Troubleshootíng



121-7



15
..
.
.
.
.
.
........
.
.
.

Starter,
removing
and
installing

(4-cylinder
engine)
....
.
.
.
............
.
121-8

Starter,
removing
and
installing

(6-cylinder
engine
with
manual
transmission)
..
.
...........
.
...
121-8

Starter,
removing
and
installing

(6-cylinder
engine
with

automatic
transmission)
................
121-9

Solenoid
switch,
removingand
installing
....
121-10

TABLES

a
.
Battery,
Starter
and
Charging
System

Troubleshooting
............
.
.
.
.
:...
........
121-2

b
.
Specific
Gravity
of
Battery
Electrolyte
at
80°F
(27°C)
...............
.
.
..
..........
121-3

c
.
Open-Circuit
Voltage
and
Battery
Charge
........
121-4

d
.
Battery
Load
Test-Minimum
Voltage
.
..........
121-4

CAUTION
-

"
Prior
to
disconnectiog
the
battery,
read
the
bat-tery
disconnection
cautions
given
at
the
front
of
this
manual
on
page
viii
.
"
Disconnecting
the
battery
cables
may
erase
fault
codes
stored
in
control
unit
memory
.

"
Always
disconnect
the
negative
()
battery
cable
first
and
reconnect
it
last
.
Cover
the
battery
post
with
an
insulating
material
whenever
the
cable
is
removed
.

"
After
reconnecting
the
battery,
the
power
window
motors
must
be
reinitialized
.
See
511
Door
Win-
dows
.

"
Never
reverse
the
battery
cables
.
Even
a
momen-
tary
wrong
connection
can
damage
the
alternatoror
other
electrical
components
.

"
Battery
cables
may
be
the
same
color
.
Label
ca-blebefore
removing
.

GENERAL

121-2



BATTERY,
STARTER,
ALTERNATOR

CHARGING
SYSTEM
TROUBLESHOOTING



Static
currentdraw,
checking

Charging
system
diagnostics
requires
special
test
equip-

ment
.
If
the
test
equipment
is
not
available,
charging
system

fault
diagnosis
can
be
performedby
an
authorized
BMW
deal-

eror
other
qualified
repair
shop
.
A
general
troubleshooting

guide
is
given
in
Table
a
.

Charging
System
Quick-Check

As
a
quick-check,
use
a
digital
multimeter
lo
measure
volt-



2
.
Disconnect
battery
negative
(-)
cable
.

age
across
the
battery
terminals
with
the
key
off
and
then

again
with
the
engine
running
.
The
battery
voltage
should
be



CAUTION-
about12
.6
volts
with
key
off
and
approximately
14
.0
volts
with



Prior
to
disconnecting
the
battery,
read
the
battery
the
engine
running
.
If
the
voltage
does
not
increase
when
the



disconnection
cautions
given
at
the
front
of
this
engine
is
running,there
is
a
fault
in
the
charging
system
.



manual
onpaga
viii
.

NOTE
-

The
regulated
voltage
(engine
running)
should
be
be-
tween
13
.5
and
14
.5,
depending
on
temperatura
and
operating
conditions
.
If
the
voltage
is
higher
than
14
.8,
the
voltage
regulator
is
most
Mely
faulty
.

Check
for
clean
and
tight
battery
cables
.
Check
the
ground

cable
running
from
the
negative
(-)
battery
terminal
lo
the

chassis
and
the
ground
cable
running
from
the
engine
lo
the

chassis
.
Check
the
alternator
drive
belt
condition
and
tension
.

If
the
battery
discharges
over
time,
there
may
be
a
constant

drain
or
current
draw
on
the
battery
.
A
small
static
drain
on
the

battery
is
normal,
but
a
largedrain
will
cause
the
battery
lo

quickly
discharge
.
Make
a
static
current
draw
test
asthe
first

step
when
experiencing
battery
discharge
.

1
.
Make
sure
ignition
and
al¡
electrical
accessories
are

switched
off
.

3
.
Connect
a
digital
ammeter
between
negative
battery

post
and
negative
battery
cable
lo
measure
current
.

See
Fig
.
1
.
Wait
at
least
one
minuta
lo
get
an
accurate

reading
.

A
range
of
about
0
lo
100
milliamps
is
normal,
dependingon

the
number
of
accessories
that
need
constant
power
.
A
current

of
400
milliamps
(0.4
amp)
or
more
may
indicate
a
problem
.

Table
a
.
Battery,
Starter
and
Charging
System
Troubleshooting

Symptom



1



Probable
Cause



1



Correctiva
Action

1
.
Engine
cranks
slowlyor
not



a
.
Battery
cables
loose,
dirty
orcor-



a
.
Clean
or
replace
cables
.
See020
Maintenance
Program
.
a
tall,
solenoíd
clicks
when



roded
.
starter
is
operated
.



b
.
Battery
discharged
.



b
.
Charge
battery,
test
and
replace
if
necessary
.
c
.
Body
ground
straploose,
dirty
or



c
.
Inspect
ground
strap,
clean,
tighten
or
replace
if
necessary
.
corroded
.
d
.
Poor
connection
at
starter
motor



d
.
Check
connections,
test
for
voltage
at
starter
.
Test
for
voltage
at
terminal
30
.



neutral
safety
or
clutch
interlock
switch
.
e
.
Starter
motor
or
solenoid
faulty
.



e
.
Test
starter
.

2
.
Battery
will
not
stay



a
.
Short
circuit
draining
the
battery
.



a
.
Test
for
excessive
current
drainwith
everything
electrical
in
the
charged
more
than
a
few



vehicle
off
.
days
.



b
.
Short
driving
trips
and
high
elec-



b
.
Evaluate
driving
style
.
Where
possible,
reduce
electrical
con
trical
drain
on
charging
system



sumption
when
making
short
trips
.
does
not
allow
battery
to
re-
charge
.
c
.
Drive
belt(s)
worn
or
damaged
.



c
.
Inspect
or
replace
multi-ribbed
belt(s)
.
See
020
Maintenance
Program
.
d
.
Battery
faulty
.



d
.
Test
battery
and
replace
íf
necessary
.
e
.
Battery
cables
loose,
dirty
orcor-



e
.
Clean
or
replace
cables
.
See
020
Maintenance
Program
.
rodad
.
f
.
Alternatoror
voltage
regulator



f
.
Test
alternator
and
voltage
regulator
.
faulty
.

3
.
Battery
losing
water
.



1
a
.
Battery
overcharging
.



1
a
.
Test
voltage
regulator
for
proper
operation
.

4
.
Lights
dim,
light
intensity



a
.
Drive
belt(s)
worn
or
damaged
.



a
.
Inspect
or
replace
multi-ribbed
belt(s)
.
See
020
Maintenance
varies
with
engine
speed
.



Program
.
b
.
Alternatoror
voltage
regulator



b
.
Test
alternator
and
voltage
regulator
.
faulty
.
c
.
Body
ground
straps
loose,
dirty
or



c
.
Inspect
ground
straps,
clean,
tighten
or
replace
as
necessary
.
corroded
.

CHARGING
SYSTEM
TROUBLESHOOTING

Fig
.1.



Electrical
system
static
current
draw
being
measured
.

To
determine
the
circuit
or
component
causing
the
problem,

remove
one
Puse
at
a
time
until
the
current
drops
to
a
normal
range
.

BATTERY
SERVICE

The
E36
uses
a
six-cell,
12-volt
leadacid
battery
mounted

in
the
luggage
compartment
.
See
Fig
.
2
.

NOTE-

E36
convertible
models
require
a
specialbattery
which
is
designed
for
constant
vibratfon
.
A
battery
not
de-signed
for
this
will
fail
much
earlier
.

Battery
capacity
is
determined
by
the
amount
of
current

needed
tostart
the
vehicle,
and
by
the
amount
of
current
con-
sumed
by
the
electrical
system
.

BMW
batteries
are
rated
by
ampere/hours
(Ah)
and
cold

cranking
amps
(CCA)
rating
.
The
Ah
rating
is
determined
by

the
average
amount
of
current
the
battery
can
deliver
over
time
without
dropping
below
a
specified
voltage
.
The
CCA
is

determined
by
the
battery's
ability
to
deliver
starting
current
at

0°
F
(-18°
C)
without
dropping
below
a
specified
voltage
.

Battery
Testing

noN~A

B9517

Battery
testing
determines
the
state
of
battery
charge
.
On

conventional
or
low-maintenance
batteries
the
most
common

method
of
testing
the
battery
is
that
of
checking
the
specific

gravity
of
the
electrolyte
using
a
hydrometer
.
Before
testing

the
battery,
check
that
the
cables
are
tight
and
free
of
corro-

sion
.
See
Fig
.
2
.

Hydrometer
Testing

The
hydrometer
consists
of
a
glass
cylinder
with
a
freely

moving
float
inside
.
When
electrolyte
is
drawn
into
the
cylin-

der,
the
levelto
which
the
float
sinks
indicates
the
specific

BATTERY,
STARTER,
ALTERNATOR



121-
3

Fig
.
2
.



Battery
in
right
sideof
luggage
compartment
.

gravity
of
the
electrolyte
.
The
more
dense
the
concentration
of
sulfuric
acid
in
the
electrolyte,
the
less
the
float
will
sink,
result-

ing
in
a
higher
reading
and
indicating
a
higher
state
of
charge)
.

NOTE-

Electrolyte
temperature
affects
hydrometer
reading
.
Check
the
electrolyte
temperaturewith
a
thermometer
.
Add
0
.004
to
the
hydrometer
reading
for
every
10°F
(6°C)
that
the
electrolyte
is
above
80°F
(27°C)
.
Sub-
tract
0
.004
from
the
reading
for
every
10°F
(6°C)
that
the
electrolyte
is
below
80°F
(27°C)
.

Before
checking
the
specificgravity
of
a
battery,
load
the
battery
with
15
amperes
for
one
minute
.
lf
the
battery
is
in-

stalled
in
the
vehicle,
this
can
be
done
by
turning
on
the
head-

lights
without
the
engine
running
.
Table
b
lists
the
percentage

of
charge
based
on
specific
gravity
values
.

Table
b
.
Specific
Gravity
of
Battery
Electrolyteat

80
°
F
(27°C)

Specific
gravity



1



Stateof
charge

1
.265



Fully
charged
1
.225



75%
charged
1
.190



50%
charged
1
.155



25%
charged
1
.120



Fully
discharged

The
battery
isin
satisfactory
condition
if
theaverage
specif-

ic
gravity
of
the
six
cells
is
at
least
1
.225
.
If
the
specific
gravity

is
above
this
leve¡,
butthe
battery
lacks
power
for
starting,
de-

termine
the
battery's
senrice
condition
with
a
load
voltage
test,

as
described
below
.
If
the
average
specific
gravity
of
the
six

cells
is
below
1
.225,
remove
the
battery
from
the
luggage

compartment
and
recharge
.
If,
after
recharging,
the
specific
gravity
varies
by
more
than
0
.005
between
any
two
celis,
re-

place
the
battery
.

CHARGING
SYSTEM
TROUBLESHOOTING