Specifications
ALTERNATORS
TESTING/TROUBLESHOOTING
PRELIMINARY
INSPECTION
Before starting the actual alternator and voltage regulator,
testing the following checks are recommended.
1. Make certain your alternator is securely mounted.
2. Check the drive belts for proper tension. Replace the
~lt
if
it is worn or glazed.
3. Check that all terminals, connectors and plugs are clean
and tight. Loose or corroded connections cause high
resistance and this could cause overcharging,
undercharging
or
damage to the charging system. Badly
corroded battery cables could prevent the battery from
reaching a fully charged condition.
4. Check the condition
of
the battery and charge
if
necessary.
A low or discharged battery may cause false or misleading
readings in the tests.
TESTING
THE
ALTERNATOR
A
CAUTION:
Before
starting
the
engine
make
certain
that
everyone
is
clear
of
moving
parts!
Keep
away
from
sheaves
and
belts
during
test
procedures.
1.
Start
the
Engine.
2. After the engine has run for a few minutes, measure the
starting battery voltage at the battery terminals using a
multimeter set on
DC
volts.
a.
If
the voltage is increasing toward
14
volts, the
alternator is working.
b.
If
the voltage remains around
12
volts, a problem
exists with either the alternator or the charging circuit;
continue with Steps 3 through
8.
MUlTIMETER
~ir!j-
'ij~~~~~~
MEASURING
~
BAlTERY
~-,.
-
YOLTAGE
ENGINE
RUNNING
3.
'fum
off
the
engine.
Inspect
all wiring and connections.
Ensure that the battery terminals and the engine ground
connections are tight
and
clean
s.
'fum
on
the
ignition
switch,
but
do
not
start
the engine.
6. Check the battery voltage.
If
your battery is in good
condition the reading
should
be
12
to
13
volts.
TESTING
THE
OUTPUT
CIRCUIT
MEASURING
BATTERY
VOLTAGE
(IGNITION
ON
ENGINE
OFF)
1. Connect the positive
probe
to the output terminal B and
connect the negative
probe
to the ground terminal E on
the alternator.
2. Wiggle the engine
wiring
harness while observing the
voltmeter. The meter
should
indicate the approximate
battery voltage, and
should
not vary.
If
no reading is
obtained,
or
if
the
reading
varies, check the alternator
output circuit for loose
or
dirty connections
or
damaged wiring.
3.
Start
the
engine.
4. Repeat the same measurement, the negative probe to
E,
the positive probe
to
B
with
the engine running. The
voltage reading should
be
between 13.5 and 14.5 volts.
If
your alternator is
over
or
under-charging, have
it
repaired at a reliable service shop.
S.
If
the
prev~ous
test reads only battery voltage at
terminal B, use the
meter
to
measure the
DC
excitation
terminal.
If
12
volts is
not
present at exciter terminal R,
inspect the wiring
for
breaks and poor connections.
Jump
12
volts from a 12 volt source (such
ad
the
battery) and operate
the
alternator.
If
the voltage output
is
13~14
volts,m then
the
alternator is OK.
Engines & Generators
29