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
