Buick LeSabre 1965 Service Manual page 589

ELECTRICAL SYSTEMS
GENERATOR-TROUBLE SHOOTING 1 0 - 1 9
from direct current charging sys-
tem circuits. Therefore, none of
the troubleshooting checks used
for direct current systems can
be used. The diodes may be
burned out if you do not observe
the following precautions:
1. Never arc terminals. Never
short between terminals on the
generator or regulator; never arc
any terminal to ground. The field
has no residual magnetism and
therefore cannot be polarized; any
attempt to do so may c a u s e
damage.
2. Always observe polarity. Use
extreme caution before installing
a b a t t e r y , connecting a fast
charger or connecting a booster
battery to insure that the ground
polarity is matched to the ground
polarity of the generator and reg-
ulator. For example, if a battery
is accidentally installed in re-
verse, the diodes in the generator
may be burned out and the wiring
harness between the generator
and battery will be burned. The
generator charging system is a
negative ground system, just as
Buick's charging systems have
always been.
3. Always disconnect battery be-
fore doing any work on the gen-
erator or regulator.
Complaints on operation of the
charging system generally fall
into one of the following classi-
fications. Go through steps listing
possible troubles in order until
the trouble is found.
a. Battery Runs Down
1. Check generator belt tension.
Belt tension as measured with
Gauge J-7316 should be 80 pounds
with a single belt or 110 pounds
with a double belt.
2. Check battery condition. Light
load test battery to see if battery
is actually low (par. 10-9). If
low, quick-charge battery and re-
test to see if battery is defective.
A battery which is sulphated or
one with an intermittent internal
"open" will remain in an under-
charged condition. Replace a de-
fective battery.
3. Check for short or ground. To
c h e c k complete car electrical
system for a short or ground,
disconnect ground cable from bat-
tery and connect a voltmeter
between ground cable and battery
post. Make sure all lights and
accessories are off and that clock
is wound. If voltmeter reads bat-
tery voltage, there is a short or
ground which must be traced and
eliminated; any reading less than
battery voltage indicates current
leakage so slight that nothing need
be done about it.
4. Check generator output. Hook-
up test instruments and check
current output of generator as
described in Delcotron Generator
Tests paragraph. If output is low,
remove generator for disassem-
bly, test and repair. If generator
output tests okay, leave test in-
struments hooked up and proceed
with Step 5.
5. Check voltage regulator set-
ting, as described in Delcotron
Generator Tests paragraph. If
voltage fluctuates, look for loose
or corroded connections in the
charging system; if none, clean
voltage contacts as described in
paragraph on Cleaning Regulator
Contacts. If voltage setting is
low, a d j u s t to specifications
shown in Figure 10-21.
If voltage setting is within the
s p e c i f i e d limits, but battery
checked low in Step 2, raise volt-
age setting slightly as described
in paragraph on Tailoring The
Voltage Setting.
b. Battery Uses Too Much
Water
1. Check battery condition. Light
load test battery to see if there is
a shorted cell (par. 10-9). A
battery having a shorted cell will
use water excessively. Replace
a defective battery.
2. Check voltage regulator set-
ting, as described in Delcotron
Tests paragraph. If voltage set-
ting is high, adjust to specifica-
tions shown in Figure 10-21. If
voltage setting is within limits,
lower voltage setting slightly as
described in paragraph on Tailor-
ing Voltage Setting.
c. Faulty Indicator Light
Operation
There are three conditions of
indicator light operation which
indicate trouble in the charging
system.
1. Indicator light on - ignition
off. This is caused by a shorted
positive diode. There will be a
continuous drain on the battery
through the generator. Remove
generator for disassembly, test
and repair.
2. Indicator light off - ignition
on. Before the engine is started,
the indicator light should glow at
about 1/2 the brightness of the
oil pressure light. If the light
does not come on, check for either
a burned out bulb or an open
in the indicator light circuit. A
shorted diode as described in Step
1 will also cause the indicator
light to go off when the ignition
is switched on.
3. Indicator light on - engine run-
ning. This can be caused by a
loose or missing belt, a defective
field relay, or a defective gen-
erator. Determine s o u r c e of
trouble as follows:
(a) Check generator belt tension.
(b) Check voltage at field relay
coil by connecting a voltmeter
from regulator "2" terminal to
ground. If voltmeter reading is
above 5 volts and the indicator
light fails to go out, field relay
is defective. Check and replace,