Service manual
ALTERNATOR
TESTING
DESCRIPTION
The
charging system consists of
an
alternator with a
voltage
regulator,
an
engine
DC
wiring
harness, a mounted
DC
cir-
cuit
breaker and a battery with connecting cables. Because of
the
use
of integrated circuits (IC's)
the
electronic
voltage
reg-
ulator
is
very
compact
and
is
mounted internally or
on
the
back
of
the
alternator.
#10
RED
CURRENT
MODEL
50
AMP
ALTERNATOR
Testing
the
Alternator
1.
Start
the Engine.
2.
After a
few
minutes of running measure
the
starting
bat-
tery
voltage at
the
battery terminals
using
a multi-meter
set on
DC
volts.
The voltage should
be
increasing
toward
14
volts.
If
it
is,
the alternator is working. Tum
to
Step
4.
TESTING
THE
STARTING
BATTERY
-
ALTERNATOR
{ENGINE
RUNNING)
MULTIMETER
#14
PURPLE
~~~~~~#10
RED
EARLY
MODEL
35AMP
ALTERNATOR
=
GROUND
TROUBLESHOOTING
A
WARNING:
A
failed
alternator
can
become
very
bot.
Do
not
touch
until
the
alternator
has
cooled
down.
This
troubleshooting section
is
to
determine
if
a problem
exists
with
the charging circuit or with the alternator.
If
it
is
determined
that the alternator or voltage regulator
is
bad,
it
is
best
to
have
a qualified technician check it
out.
The
alternator charging circuit charges the starting battery
and
the service
battery.
An isolator with a diode, a solenoid,
or
a battery selector switch
is
usually mounted in the circuit
to
isolate the batteries
so
the
service battery
is
not discharged
along
with
the
service
battery.
If
the
alternator
is
charging
the
starting
battery
but
not
the
service
battery,
the problem
is
in
the
service
battery
charging circuit
and
not
with.the
alternator.
A
WARNING~
Before
starting
the
engine
make
certain
that
everyone
is
clear
of
moving
parts!
Keep
away
from
sheaves
and
belts
during
test
procedures.
A
WARNING:
Multimeters
and
DC
Circuits:
DC
and
AC
circuits
are
often
mixed
together
in
marine
applications.
Always
disconnect
shore
power
cords,
isolate
DC
and
AC
converters
and
shut
down
generators
before
pertonning
DC
testing.
No
AC
tests
should
be
made
without
proper
knowledge
of
AC
circuits.
37
B+
OUTPUT
To
starter
motor
3.
If
the starting battery voltage remains around
12
volts
after the engine
is
started and run
for
a
few
minutes, a
problem exists with
the
alternator or
the
charging circuit.
a. Turn off the
engine.
Inspect all wiring and connections.
Ensure that the battery terminals and
the
engine ground
connections
are
tight and clean.
A
CAUTION:
To
avoid
damage
to
the
battery
charging
circuit,
never
shut
off
the
engine
battery
switch
when
the
engine
is
running!
b.
If
a battery selector switch
is
in the charging circuit,
ensure that it
is
on
the correct setting.
c.
Turn
on
the ignition switch,
but
do
not
start
the
engine.
d.
Check the battery voltage.
If
your
battery
is
in
good
condition the reading should
be
12
to
13
volts.
cmJ
0
TESTING
THE
COM
ALTERNATOR
VOLTAGE
{IGNITION
ON
-
ENGINE
OFF)
MULTIMffiR