Installation manual
DC
ELECTRICAL
SYSTEM
7.
Now check the voltage between the alternator output
ter-
minal (B+) and ground.
If
the circuit
is
good, the voltage
at
the alternator will be the same as the battery, or
if
an isola-
tor
is
in
the
circuit the alternator voltage will be zero.
If
neither
of
the above
is
true, a problem exists in the circuit
between the alternator and the battery. Check all the
connections - look for an opening in the charging circuit.
TESTING
THE
STARTING
BATTERY/ALTERNATOR
(ENGINE
RUNNING)
MULTIMETER
ENGINE
-c==>-'
GROUND
8. Start the engine again. Check the voltage between the
alternator output and ground.
The voltage reading for a properly operating alternator
should be between 13.5 and 14.5 volts.
If
your alternator
is over- or under-charging, have it repaired at a reliable
service facility.
NOTE:
Before removing the alternator
for
repair; use a
voltmeter to ensure that
12
volts DC excitation is present
at
the EXC terminal if the previous test showed only bat-
tery voltage at the B output terminal.
If
12
volts is not present
at
the
EXC
terminal, trace the
wiring and
lookfor
breaks
and
poor
connections.
Checking
the
Service
Battery
Check the voltage
of
the service battery. This battery should
have a voltage between
13
and
14
volts when the engine
is
running.
If
not, there
is
a problem in the service battery
charging circuit. Troubleshoot the service battery charging.
circuit by checking the wiring and connections, the
solenOId,
isolator, battery switch, and the battery itself.
MUlTIMETE.
i
COM
GROUND
SERVICE
BATTERY
TESTING
THE
SERVICE
BATTERY
(ENGINE
RUNNING)
A
CAUTION:
To
avoid
damaging
the
alternator
diodes,
do
not
use
a
high
voltage
tester
(i.e.
a
megger)
wilen
performing
tests
on
the
alternator
charging
circuit.
Engines & Generators
29