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.
f14
BROWN·=~=:~-_
114
GREY==~=5:~",=-
......
1.
Start the
Engin~
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,
your
alternator
is working.
3. Turn to step 5 on the next page.
MULTI
METER
114
PURPLE==#i~iiiii®
;;;:"~
114
B~L~UE~~~.~~~
Gt'f'~=
1t4
BROWN
114
PINK·
to
Tachometer
to
Fuel
Solenoid
IFuel
Lift
Pump
51
AMP
ALTERNATOR
(GENERATOR)
\\...~~~~~~=
ItO
RED
11+
OUTPUT
TROUBLESHOOTING
A
WARNING:
A
failed
alternator
can
become
very
hot.
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 alterna-
tor.
Testing
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.
NOTE:
Multimeters and DC Circuits
DC and A
C circuits
are
often mixed together
in
marine
appli-
cations.
Always disconnect shore power
cords,
isolate
DC
and AC converters and shut down generators
before
per-
forming DC
testing.
No
AC
tests should
be
made
without
proper
knowledge
of
AC
circuits.
to
Starter
Motor
TESTING
THE
STARTING
BATTERY·ALTERNATOR
(ENGINE
RUNNINP)
GROUND
4.
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
otT
the engine. Inspect all wiring and connec-
tions. Insure 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
mnning!
B. If a battery selector switch is
in
the charging circuit,
insure 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.
TESTING
THE
ALTERNATOR
VOLTAGE
(IGNITION
ON
-
ENGINE
OFF)
aml
G
coM
MULnMETER
STARTING
BATTERY
Engines & Generators
_GROUND
46