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UNDERCHARGED BATTERY
This condition, as evidenced by slow
cranking and low specific gravity read-
ings, can be caused by one or more of
the following conditions even though
the indicator lamp may be operating
normally .
The following procedure
also
applies
to
circuits
with
an
ammeter :
1. Insure that the undercharged condit-
ion has not been caused by acces-
sories having been left on for ex-
tended periods .
2. Check the drive belt for proper
tension .
3. If a battery defect is suspected, see
"Battery
Service
And
Diagnosis"
earlier in this section.
4.Inspect
the
wiring
for
defects .
Check all connections for tightness
and cleanliness, including the slip
connectors at
the
generator
and
firewall, and the cable clamps and
battery posts.
5 . Check operation of diode assembly
as follows :
With the engine operating at fast
idle, use a voltmeter to measure
voltage at the three terminals of the
diode assembly. Attach the positive
lead to the indicated terminal, the
negative lead to chassis ground .
a. With positive lead to generator
terminal on diode assembly and
negative lead to ground, reading
should be 13.1 to 15.5 volts .
If
reading at generator terminal is
zero volts, check wiring to gen-
erator for open connection.
b. With positive lead to bat . No . 1
terminal on diode assembly and
negative lead to ground, reading
If ampere output is within
10 amps of rated output as
stamped
on
generator
frame,
generator
is
not
defective ; recheck Steps 1
through 6 .
If test hole is accessible,
ground the field winding by
inserting a screwdriver into
the test hole .
CAUTION :
Tab is within
3/4-inch of casting surface.
Do
not
force screwdriver
deeper than 1-inch into end
frame .
Operate engine at moderate
speed as required, and adjust
carbon pile as required to
obtain
maximum
current
output .
If output is not within 10
amps of rated output, check
the field winding, diode trio,
rectifier bridge, and stator
as covered in "GENERATOR
REPAIR ."
GENERATING SYSTEM DIAGNOSIS
should be 12 .1 to 14.5 volts.
c. With positive lead to bat. No . 2
terminal and negative lead to
ground, reading should be 12 .1 to
14.5 volts.
If reading on bat . terminal No . 1 or
No. 2 is zero volts, replace diode
assembly .
Reading at battery term-
inals No.
1 and No.
2
should
be
approximately 1 .0 volts less than read-
ing at generator terminal .
If reading
at bat . terminals is more than 1 .0 volts
less than generator terminal reading,
replace diode assembly.
If readings at generator terminal
and bat. terminals are identical, see
"Discharged Batteries" in this chart .
6 . With engine running, connect a volt-
meter from :
a . Generator
"BAT"
terminal
to
ground .
b . Generator
No .
1
terminal
to
ground.
c . Generator
No .
2
terminal
to
ground.
A zero reading indicates an open
between voltmeter connection and
battery .
7 . If previous Steps 1 through 6 check
satisfactorily, check generator as
follows :
a . Disconnect battery ground cable .
b . Connect
an
ammeter
in
the
circuit at the "BAT" terminal of
the generator .
c . Reconnect battery ground cable.
d . Turn on radio, windshield wipers,
lights
high
beam
and
blower
motor high speed .
Connect a
carbon pile across the battery .
e . Operate
engine
at
moderate
speed as
required, and adjust
carbon pile as required, to obtain
maximum current output .
If
amperes
output is not
within 10 amps of rated out-
put, determine if test hole is
accessible .
If test hole is not accessible,
disassemble
generator
and
make tests listed in "GEN-
ERATOR REPAIR ."
If output is within 10 amps
of rated output, test regu-
lator
with
an
approved
regualtor tester, and check
field winding as covered in
"GENERATOR REPAIR ."
ENGINE ELECTRICAL 6Y- 5
2 .
OVERCHARGED BATTERY
1 . To determine battery condition, see
"Battery
Service
And
Diagnosis"
earlier in this section.
2 . Connect a voltmeter from generator
No . 2 terminal to ground. If reading
is zero, No . 2 lead circuit is open .
3 . If battery and No . 2 lead circuit
check good, but an obvious over-
charge condition exists as evidenced
by excessive battery water usage,
proceed as follows:
a . Separate end frames as covered
in "Disassembly" under heading
of
"GENERATOR
REPAIR ."
Check field winding for grounds
and shorts, If defective, replace
rotor and test regulator with an
approved regulator tester .
b . Connect ohmmeter using lowest
range scale from brush lead clip
to end frame; then reverse lead
connections .
c . If both readings are zero, either
the brush lead clip is grounded or
regulator may be defective .
d. A grounded brush lead clip can
result from omission of insulat-
ing washer, omission of insulat
ing sleeve over screw, or dam-
aged insulating sleeve.
Remove
screw to inspect sleeve . If satis-
factory, test regulator with an
approved regulator tester .
DISCHARGED BATTERIES
This condition could exist if a failed
diode
assembly
allows
the
vehicle
automotive
battery
or
living
area
battery to be discharged by the other
circuit
(i .e.,
no
isolation
between
battery circuits) during times when the
engine is not in operation .
To check
diode continuity and resistance :
1 . Disconnect all leads to
diode
assembly .
Connect ohmmeter :leads to gen-
erator terminal and bat .
No . 1
terminal
at
diode
assembly .
Using appropriate scale, observe
reading . Reverse lead connect-
ions to terminals and observe
reading using appropriate scale .
If both readings are the same,
replace diode assembly .
A good
diode section will give one high
and one low reading .
3 . Repeat
above
procedure
with
ohmmeter leads connected to gen-
erator terminal and bat . No . 2 term-
inal .
Using
appropriate
scale,
observe reading . Reverse lead con-
nections to terminals and observe
reading using appropriate scale .
If
this test gives one high and one low
reading, diode assembly is good . If
both readings are the same, replace
diode assembly .
A-6193
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