Motor BMW 325i 1992 E36 Service Manual

541-2



CONVERTIBLE
TOP

Fig
.
2
.



Manually
operated
frontlatch
.
Loosen
mounting
nuts
(A)
and
locknut
(B),
then
adjust
latch
height
with
hex-bolt
(C)
.
(Fully
automatic
front
latch
height
adjuster
is
similar
.)
Latch
tension

ís
adjusted
at
rod
ball-joint
end
(D)
.

Convertible
Top
Lid
Release
Mechanism

The
convertible
lid
release
handle
is
situated
in
the
trim

panel
behind
the
driver's
seat
.
To
remove
thehandle,
pull
its

plastic
insert
forward
and
remove
the
triminsert
.
The
handle
is

mounted
with
a
single
screw
.

Abowden
cable
is
routed
from
the
handle
to
the
left
lid
latch
.

Another
cable
is
routed
from
the
left
tothe
right
latch
inside
the

luggage
compartment
.
It
is
accessed
by
pulling
down
the
trim

lining
off
the
front
wall
of
the
compartment
.

Convertible
top
and
frame,
replacing

1
.
Open
convertible
top
partially
.
Open
convertible
top
lid
.



J
I~I~KX
Open
back
windows
.



_

v
2
.
Remove
fasteners
in
compartments
behind
door
posts

and
lift
out
complete
top
.
Count
number
of
shims
on

horizontal
mounting
bolts
.
See
Fig
.
3
.

3
.
Installation
is
reverse
of
removal
.
Be
sure
to
replaceU-
shaped
shims
on
horizontal
mounting
bolts
.
See
Fig
.
4
.

Fig
.
4
.



Horizontal
positioning
bolt(A)
and
U-shaped
adjusting
shims4
.
To
adjust
position
and
fit
oftop,
remove
or
add
U-



(B)for
convertible
top
.
One
of
two
main
mounting
nuts
(ar
shaped
shims
until
top
is
properly
aligned
.
Tighten
nuts



rows)
also
visible
.

and
screws
.

POWER
CONVERTIBLE
TOP

The
semi-automatic
top,
installed
in
1996
convertibles,

must
first
be
manually
released
from
the
visor
latch
plates
and
pushed
back
past
the
"tension
point,"
wheréupon,
the
auto-
matic
retracting
motor
and
linkage
take
over
and
pull
it
into
the
storage
compartment
behind
the
back
seat
.

POWER
CONVERTIBLE
TOP

Fig
.
3
.



Mounting
nuts
(A)
for
convertible
top
(two
oneach
side)
.
There
is
also
a
horizontal
bolt
with
spacers
oneach
side
(B)
.

0012754

The
fully
automatic
top,
standard
on
1997
and
later
convert-

ibles,
allows
complete
operation
of
the
top,
from
fully
open
to
fully
closed,withthe
push
of
atoggleswitch
on
the
console
.

The
top
switch
incorporates
a
"top
unlatched"
warning
LED
.

A
schematic
representation
of
the
fully
automatic
convert-
ible
top
is
shown
in
Fig
.
5
.

KL
30
CONVERTIBLE
BATTERY

(ON
TOP
MOTOR)

UP

DOWN

S2
-I
(ON
TOP
MOTOR)

(IN
TOP
STORAGE
WELL)

S4
E36
AUTOMATIC
CONVERTIBLE
S5
(ON
TRUNK
LOCK)I
TOP
CONTROLMODULE

I
LH
SIDE
TOP
LATCH
DRIVE)
1

M-4
m
í
A
7--
Offi-

Íl

ít~~

ENSOR

H
ARD
T
OP
LOCK
SIGNAL
O

1~~11
:i
q
SIGNAL

TOP
MOTOR
POSITION
SIGNAL

Fig
.
5
.



Semi-automatic
and
fully
automatic
convertible
top
system
.
Main
ad-
ditional
components
in
fully
automatic
top
shown
inside
dashed
lines
.

CONVERTIBLE
TOP



541-3

TOP
LID
MOTOR

EM
TOP
n

~
ll
í
9
.1

-----------
II



II
FRONT
I
M
LATCH
I

1



MOTOR
'I
I



1I
L---------
J
X

POWER
CONVERTIBLE
TOP

541-
4



CONVERTIBLE
TOP

Folding
roof

Frontlatches

Convertible
topframe

i

Lower
mounting
pata
Horizontal
positioning
~~-
bolt
Manual
front
8
e
latch



1
handle

~



O

Visor
latchplata

Fig
.
6
.



Mechanical
components
of
E36
convertible
top
.
Manual,
semi-automatic,
and
fully
automatic
tops
have
similar
mechanical
construction
.

NOTE-

The
electronic
circuits
used
to
controlconvertible
top
operation
arecomplex
.
Diagnosis
of
the
convertible
top
and
the
Rollover
Protection
System
are
beyond
the
scope
of
this
book
.
Your
authorized
BMW
dealer
has
the
proper
diagnostic
equipment
and
tools
to
carry
out
these
tasks
.

Front
Latching
Mechanism

A
close,
tight
fit
between
the
front
bow
of
the
convertible

roof
and
the
top
of
the
windshield
is
critical
for
preventing

moisture
and
wind
noise
from
intruding
into
the
passenger

compartment
.

Visor
Latch
Plate

The
left
and
right
visor
latch
plates
can
be
accessed
by
re-

moving
the
trim
and
moldings
aroundthe
sides
and
top
of
the
windshield
.
Each
latch
is
attached
to
thetop
of
the
windshield
using
three
bolts
.
Latch
position
is
adjusted
as
follows
:

"
Loosen
bolts

Latch
top

"
Align
top

"
Retighten
bolts
.
See
Fig
.
7
.

POWER
CONVERTIBLE
TOP

4
a

0012756

Visor
Latch

0012768

Fig
.
7
.



Visor
latchplate
is
heldto
top
of
windshieldwiththreebolts
(arrows)
.

The
semi-automatic
and
the
fully
automatic
top
front
latches

are
of
similar
design
.
For
the
automatic
latching
mechanism

an
additional
motor
has
been
installed
in
the
front
bow
of
the
convertible
top
.
This
releases
the
top
from
the
visor
latch

plates
and
pulís
it
back
far
enough
for
the
main
retracting
mechanism
to
complete
thejob
.

The
latches
and
the
motor
can
be
accessed
byremovingthe
front
cover
trim
from
the
convertible
top
.

The
left
latch
in
the
fully
automatic
version
hastwo
mi-
croswitches
(S7
and
S8)which
signal
open,
closed
and
latched
states
.
See
Fig
.
8
.

The
length
of
the
dead
center
point
rod
is
critica¡
lo
correct
opening
and
latching
of
the
convertible
top
.
See
Fig
.
9
.

Dead
Center
Point
Rod

"
Dimension
A
........
205
.5
f
1
mm
(8
.09
t0
.04
in)

Visor
Latch
Motor

The
fully
automatic
convertible
top
is
latched
and
unlatched
by
one
electric
motor
installed
in
the
front
roof
bow
.
To
re-
place,
remove
front
cover
trim
from
the
roof
.
Remove
electri-
cal
harness
connectors
from
motor,
andremove
mounting
screws
.
Slide
the
motor
off
the
output
shafts
to
the
left
and
right
latches
.

During
reinstallation,
theoutput
shafts
must
be
tumed
until
the
S8
microswitch
in
the
left
latch
is
tripped
.

Convertible
top
and
frame,
replacing

1
.
Open
convertible
top
partially
.
Open
convertible
top
lid
.



Fig
.
9
.



Preset
lengthof
dead
centerpoint
rod
.
Open
back
windows
.

2
.
Fully
automatic
power
convertible
top
:
Remove
front
cover
trim
from
top
.
Disconnect
electrical
harness
con-

nectors
from
frontlatch
motor
.
Disconnect
connectors

from
S7
and
S8
microswitches
at
left
latch
.

Motors
M1
Convertible
top
M2
Convertible
top
lid
M3Front
latch
(fully
automatic
top)

Microswitches
S1
&S2
In
convertible
top
motor
S3
In
convertible
top
storage
compartment
S4
In
top
linkage
(semi-automatic
only)
S5
In
luggage
compartment
latch
S6
In
right
convertible
top
lid
latch
S7&S8
In
left
conv
.
top
latch
(fully
automatic)

Fig
.
8
.



Locationof
automatic
and
semi-automatic
convertible
latch
mechanisms,
motors
and
microswitches
.

CONVERTIBLE
TOP



541-5

POWER
CONVERTIBLE
TOP

541-
6



CONVERTIBLE
TOP

3
.
Remove
headliner,
starting
from
front
and
working



7
.
Remove
fasteners
in
bottom
of
storage
compartments

backward
.
Note
arrangement
and
lacing
of
tensioning



behind
door
posts
and
lift
out
complete
top
.
Note
num

cable
so
it
can
be
reinstalled
in
its
original
configura-



ber
of
shims
on
horizontal
mounting
bolt
.
See
Fig
.
12
.

tion
.
See
Fig
.
10
.

0012748

Fig
.
10
.
Headliner
tensioning
cable
and
some
of
its
retaining
eyelets
(arrows)
.

4
.
Disconnect
electrical
harness
connector
from
S4
mi-

croswitch
in
middle
linkage
of
convertible
top
.

5
.
Disconnect
electric
motor
linkage
rods
in
convertible

top
storage
compartment
behind
left
rearseat
.
See
Fig
.

Vizib1

Fig
.
11
.
Convertible
top
linkage
rods(arrows)
in
compartment
behind
left
rear
seat
.

POWER
CONVERTIBLE
TOP

8
.
Installation
is
reverse
of
removal
.
Be
sure
to
replace
U-

shaped
shims
on
horizontal
mounting
bolts
.
See
Fig
.

13
.

0012754

Fig
.
13
.
Horizontalpositioning
bolt
(A)
and
U-shaped
adjusting
shims
(B)
for
convertible
top
.
One
of
two
main
mounting
nuts
(ar-
rows)
also
visible
.

6
.
Pull
electrical
harness
through
to
disengage
from
top
.



9
.
To
adjust
position
and
fit
oftop,
Rmove
or
add
U-
shaped
shims
until
top
is
properly
aligned
.
Tighten
nuts

and
screws
.

Convertible
top
drive
motor,
replacing



5
.
Working
in
convertible
top
storage
compartment
be-
hind
driver's
seat,
remove
convertible
top
linkage
rods
1
.
Open
convertible
top
partially,
stopping
when
convert-



from
top
of
motor
.
Refer
to
Fig
.
11
.
ible
top
lid
is
fully
upen
.
Remove
lid
.

2
.
Release
luggage
compartment
lock-out
by
pressing
on
microswitch
in
right
convertible
top
lid
latch
.
See
Fig
.

14
.

0012745

Fig
.
14
.
Rightside
convertible
top
lid
latch
.
Arrow
points
to
location
of
luggage
compartment
lock-out
microswitch
.

3
.
Open
luggage
compartment
.
Remove
trim
and
inner

lining
from
left
side
of
compartment
.

4
.
Disconnect
electrical
harness
connectors
at
top
motor
.

Release
emergency
release
cable
from
lever
.
Push
le-

ver
up
to
release
motor
.
See
Fig
.
15
.

uu12759

Fig
.
15
.
Convertible
top
motor
(A)
and
release
lever
(B)
in
luggage

compartment
.

CONVERTIBLE
TOP



541-
7

6
.
Remove
four
fastenersholding
motor
to
body
and
re-

move
motor
through
luggage
compartment
.
See
Fig
.

16
.

0012761

Fig
.
16
.
Convertible
top
motor
mountingscrews
(arrows)
.
Gasket
(A)
mustbe
renewed
when
motor
is
replaced
.

7
.
Installation
is
reverse
of
removal
.
Keep
the
following
in

mind
:

"
Replace
sealing
gasket
between
top
of
motor
and

body
.

"
Securemotormountingscrews
with
Locktite
®
270
or
equivalent
.

Tightening
Torque

"
Convertible
top
motor
to
body

mountingscrews
...
...
.
.
.........
10
Nm
(7
.5
ft-Ib)

Convertible
Top
Emergency
Operation

A
malfunction
in
the
electrical
system
or
another
fault
in
the

convertible
top
mechanism
can
cause
the
automatic
or
semi-
automatic
top
to
be
stuck
in
open,
shut,
or
intermediate
posi-

tion
.
The
following
general
procedures
are
suggested
in
order

to
close
the
top
in
an
emergency
situation
.
Resetting
proce-

dures
for
convertible
top
synchronization
after
emergency
clo-

sure
are
beyond
the
scope
of
this
manual
.

Main
Motor
.
To
release
thetop
linkage
from
the
motor,
lift

the
left
comer
of
the
rearseat
to
access
emergency
release

handle
.
See
Fig
.
17
.

POWER
CONVERTIBLE
TOP

541-
8



CONVERTIBLE
TOP

CAUTION-

In
caseof
failure
of
the
automatic
or
semi-auto-
matic
convertible
top
function,
only
use
the
emer-
gency
procedure
to
close
the
top,
never
to
open
it
.
An
authorized
BMW
dealer
should
then
be
con-
sulted
.

0012764

Fig
.
17
.
Convertible
topmotor
emergency
release
handle
under
rear
seat
.
Pull
in
direction
of
arrow
to
release
top
.

It
is
then
possible
to
push
thetop
manually
to
a
near
closed
position
.
In
the
case
of
the
semi-automatic
top,
simply
attach

and
lock
the
front
latches
.

Front
Latches
.
Once
the
fully
automatic
convertible
top
has
been
released
from
the
motor
and
manually
pushed
to
near-closure,
emergency
latchíng
ofthetop
is
possible
by
us-
ing
the
S-shaped
hex
key
provided
in
the
emergency
tool
kit
.

First,
remove
the
plastic
cover
over
the
latch
motor
in
the
front
bow
of
the
convertible
top
.
See
Fig
.
18
.

Next,
use
the
hex
key
from
tool
box
to
crank
the
front
latch-
es
shut
.
See
Fig
.
19
.

Luggage
Compartment
Cover
.
A
microswitch
in
the
right
convertible
top
lid
latch
prevents
the
luggage
compartment
from
being
opened
whilethe
lid
is
up
.
This
lockout
can
be
overridden
by
pressing
on
the
microswitch
.
Refer
toFig
.
14
.

POWER
CONVERTIBLE
TOP

Fig
.
18
.
Remove
plastic
cover
from
center
of
convertible
roof
front

bow
to
access
latching
motor
drive
.

0012762

Fig
.
19
.
Using
emergency
hexkey
to
move
front
part
of
convertible
top
.

CAUTION-

The
convertible
top
lid
and
the
luggage
compart-
ment
cover
interfere
with
each
other
and
cannot
beopen
at
the
same
time
.
To
avoid
damage
to
painted
surfaces,
an
assistant
should
keep
the
lid
down
until
the
luggage
compartment
cover
can
beclosed
.

Convertible
Top
Lid

The
components
of
the
convertible
top
lid
are
shown
in
Fig
.
20
.

Fig
.
20
.
Components
of
the
convertible
top
lid
.

ROLLOVER
PROTECTION
SYSTEM

The
lid
latches
are
cable
operated
by
a
drive
motor
located
in
the
left
sideof
the
luggagecompartment,
behind
the
trim
lin-

er
.
The
same
motor
is
used
to
raise
and
lower
the
lid
during

automatic
convertible
topoperation
.

The
latch
cables
must
be
adjusted
so
that
the
lidfits
snugly
against
the
body
when
locked
.

The
lid
drive
motor
can
be
removed
and
replaced
from
the

luggage
compartment
.

Two
spring-locaed
cassettes
are
mounted
behind
the
rear
seat
.
A
single
rollover
sensor,
mounted
on
the
left
cassette,
signals
the
convertible
top
module
(CVM)
of
animminent
roll-
over,
whereupon
the
module
triggers
both
cassettes
within

3j10th
of
a
second
.
See
Fig
.
21
.

Once
the
cars
ignition
has
been
switched
on,
the
rollover

sensor
performs
a
self-test
lasting
6
seconds
.
During
this
time

a
yellow
warning
light
is
lit
on
the
dashboard
.
If
thewarning
lightfails
to
go
out
after
6
seconds,
this
means
that
a
fault
has

been
detected
in
the
system
.
The
fault
is
stored
in
the
CM

Faults
canbe
retrieved
and
diagnosedby
special
diagnostic

equipment
.

NOTE-

Diagnosis
of
the
convertible
top
and
the
Rollover
Pro-
tection
System
are
beyond
the
scope
of
this
book
.
Your
authorized
BMW
dealer
has
the
proper
diagnostic
equipment
and
tools
to
carry
out
these
tasks
.

CONVERTIBLE
TOP



541-
9

Fig
.
21
.
Construction
of
the
rollover
protection
cassette
.

After
deployment,
thedetent
pawl
in
a
rollover
protection
cassette
can
be
retracted
using
the
special
tool
in
the
tool
kit,
fitted
to
the
screwdriver
handle
.
The
rear
seatheadrest
needs
to
be
raised
for
this
procedure
.

WARNING
-

Ensure
that
the
area
above
and
adjacent
to
the
roll-
over
bars
remains
clear
and
unobstructed
at
all
times
.

CAUTION-

"
Itis
not
possible
to
close
the
convertible
top
with
the
rollover
bars
extended
.

"
If
a
hardtop
is
mounted,
be
sure
to
install
the
pro-
tective
rollover
bar
covers
provided
with
the
hard-
top
to
prevent
damaglng
the
rear
window
in
case
of
deployment
.

0012744

ROLLOVER
PROTECTION
SYSTEM

NOTE
-

Sometimes
the
color
of
en
installed
wire
may
be
differ-
ent
than
the
one
on
the
wiring
diagram
.
Don't
be
con-
cerned
.
Just
be
sure
lo
confirm
that
the
wire
connects
lo
the
proper
terminals
.

Wire
color
codes

"
BLU
.........
.
..
..
...
.
.................
Blue

"
BRN
....:....
.
..
..
...
..
...............
Brown

"
YEL
.........
.
..
..
...................
.Yellow

"
GRN
.........
.
..
..
...
.
................
creen

"
G
RY
.......
.
.
.
..
..
.....................
G
ray

"
ORG
.........
.
..
..
...
.
..............
.Orange

"
RED
......
...
.
.
..
.....................
.Red

"
BLK
.........
.
..
..
...
.
................
Black

"
VIO
..........
.
..
...
..
..
.......
.
.......
Violet

"
WHT
.........
.
.
....
.
...
:..............
White

Table
a
.
Terminal
and
Circuit
Numbers

Number



1
Circuít
description

1



j
Low
voltage
switched
terminal
of
coi¡

4



1
High
voltage
center
termina¡
of
coi¡

+x



Originates
atignition
switch
.
Supplies
powerwhen
the
ignition
switch
is
in
the
PARK,
RUN,
or
START
position

15



Originates
atignition
switch
.
Supplies
powerwhen
ignition
switch
is
in
RUN
or
START
position

30



Battery
positive
(+)
voltage
.
Supplies
power
whenever
battery
is
connected
.
(Not
dependent
on
ignition
switch
position,
unfused)

31



1
Ground,
battery
negative
(-)
terminal

50



Supplies
power
from
battery
to
starter
solenoid
when
ignition
switch
isin
START
position
only

+54



Originates
atignition
switch
.
Supplies
power
when
ignition
switch
isin
the
RUN
position
only

85



1
Ground
side
(-)
ofrelay
coil

86



1
Power-in
side
(+)
ofrelay
coil

87



1
Relay
actuatedcontact

D



Alternator
warning
light
and
field
energizing
circuit

ELECTRICAL
SYSTEM-GENERAL
600-
3

Additional
abbreviations
shown
in
the
wiring
diagrams
are

given
below
.

Abbreviations

"
ABS
........
.
...
.
...
.
..........
antilock
brakes

"
A/C
........
.
...
..
..
.
.........
.airconditioning

"
AST/ASC+T
.......
...
.
.
.......
al¡
season
traction

"
CONV
.......
.
.
...
.................
convertible

"
DME
........
.
.
...
.......
digital
motor
electronics

"
ECM



.......
.
...
..
..
.
..
electronic
control
module

"
EWS/EWS
II
......
...
.
.
coded
driveaway
protection

"
SRS
........
.
supplemental
restraint
system-airbag

"
TCM
........
.
..
....
.
transmission
control
module

"
ZKE
(94-98
models)
..
..
.
...
central
body
electronics

"
ZVM
(92-93
models)
...
.
.
..
.
.......
central
locking

ELECTRICAL
TROUBLESHOOTING

Most
terminals
are
identified
by
numbers
on
the
compo-

nents
and
harness
connectors
.
The
terminal
numbers
for
ma-



Four
things
are
required
for
current
toflow
in
any
electrical

jor
electrical
connections
are
shown
in
the
diagrams
.
Though



circuit
:
a
voltagesource,
wires
or
connections
to
transport
the

many
terminal
numbers
appear
only
once,
severa¡other
num-



voltage,
a
load
or
device
that
uses
the
electricity,
and
a
con-
bers
appear
in
numerous
places
throughout
the
electrical
sys-



nection
to
ground
.
Most
problemscanbefound
using
a
digital

tem
and
identify
certain
types
ofcircuits
.
Some
of
the
most



multimeter
(volt/ohm/amp
meter)to
check
for
voltage
supply,

common
circuit
numbers
are
listed
below
in
Table
a
.



for
breaks
in
the
wiring
(infinite
resistance/no
continuity),
orfor

a
path
to
ground
that
completesthe
circuit
.

Electric
current
is
logical
in
its
flow,
always
moving
from
the

voltage
sourcetoward
ground
.
Electricalfaults
can
usually
be

located
through
a
process
of
elimination
.
When
troubleshoot-

ing
a
complex
circuit,
separate
the
circuit
into
smaller
parts
.

The
general
testsoutlined
below
may
be
helpful
in
finding

electrical
problems
.
The
information
is
most
helpful
when

used
with
the
wiring
diagrams
.

Be
sure
to
analyze
the
problem
.
Use
the
wiring
diagrams
to

determine
the
most
likely
cause
.
Getan
understanding
of
how

the
circuit
works
by
following
the
circuit
from
groundback
to

the
power
source
.

When
making
test
connections
at
connectors
andcompo-

nents,
use
care
to
avoidspreading
or
damaging
the
connec-

tors
or
terminals
.
Some
tests
may
require
jumper
wires
to

bypass
components
or
connections
in
the
wiring
harness
.

When
connecting
jumper
wires,
use
bladeconnectors
at
the

wire
ends
that
match
the
size
of
the
terminal
being
tested
.
The

small
interna¡
contacts
are
easily
spread
apart,
and
this
can

cause
intermittent
or
faultyconnections
that
can
leadto
more

problems
.

ELECTRICAL
TROUBLESHOOTING

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
.