GMC 1976 ZEO 6083 Maintenance Manual page 402

6Y- 22
ENGINE ELECTRICAL
battery may be between the terminals, at the crimp
between the harness wire and terminal, or in the
wire .
Generator on Vehicle Output Test
6. If previous Steps 1 through 5 check satisfac-
torily, check Delcotron 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 re-
quired, and adjust carbon pile as required, to obtain
maximum current output .
f. If ampere output is within 10 amperes of
rated output as stamped on generator frame, genera-
tor is not defective; recheck Steps 1 through 5 .
g. If ampere output is not within 10 amperes
of rated output, determine if test hole (figure 25) is
accessible .
If accessible go to Step h. If not accessible go
to Step 1 .
h. Ground the field winding by inserting a
screwdriver into the test hole (figure 25). CAU-
TION : Tab is within 3/4 inch of casting surface. Do
not force screwdriver deeper than one inch into end
frame.
i. Operate engine at moderate speed as re-
quired, and adjust carbon pile as required to obtain
maximum current output .
j. If output is within 10 amperes of rated out-
put, check field winding as covered in "GENERA-
TOR REPAIR" section, and test regulator with an
approved regulator tester .
k. If output is not within 10 amperes of rated
output, check the field winding, diode trio, rectifier
bridge, and stator as covered in "GENERATOR
REPAIR" section.
1. If test hole is not accessible, disassemble
generator and make tests listed in "GENERATOR
REPAIR" section.
OVERCHARGED BATTERY
1 . To determine battery condition, check per ap-
plicable battery device and diagnosis given 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 overcharge condition exists as evi-
denced by excessive battery water usage, proceed as
follows:
a. Separate and flames as covered in "Disas-
sembly" section 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 as shown in
Step 1, Figure 26, 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 insulating washer (figure 26), omission
of insulating sleeve over screw, or damaged insulat
ing sleeve . Remove screw to inspect sleeve . If satis-
factory, test regulator with an approved regulator
tester .
Figure 25-End View of Generator (Typical)