Chevrolet Light Duty Truck 1973, Service Manual

Page: 551 / 979

E N G I N E E L E C T R IC A L 6 Y - 2 3
Check energizer. Test is not valid unless energizer is
good and fully charged.
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.
With ignition switch “on” connect a voltmeter from
generator “BAT” terminal to ground, generator No.
1 terminal to ground and generator No. 2 terminal
to ground. A zero reading indicates an open
between voltmeter connection and Energizer.
NOTE: An open No. 2 lead circuit on
generators will cause uncontrolled voltage,
Energizer overcharge and possible damage to
Energizer and accessories. Generators sup­
plied for current applications have a built-in
feature which avoids overcharge and acces­
sory damage by preventing the generator
from turning on if there is an open in the
wiring harness connected to the No. 2
generator terminal. Opens in the wiring
harness connected between the No. 2
generator terminal and Energizer may be
between the terminals, at the crimp between
the harness wire and terminal, or in the wire.
If previous Steps 1 through 5 check satisfactorily,
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 required,
and adjust carbon pile as required, to obtain
maximum current output.
f. If ampere output is within 10 percent 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 percent of
rated output, ground the field winding by
inserting a screwdriver into the test hole (Fig.
1C).
CAUTION:
Tab is within 3/4 inch of casting
surface. Do not force screwdriver deeper than
one inch into end frame.
h. Operate engine at moderate speed as required,
and adjust carbon pile as required to obtain
maximum current output.
i. If output is within 10 percent of rated output,
replace regulator as covered in the Overhaul Manual
and check field winding.
j. If output is not within 10 percent of rated
output, check the field winding, diode trio,
rectifier bridge, and stator as covered in the
Chassis Overhaul Manual.
k. Remove ammeter from generator and turn
accessories off.
OVERCHARGED ENERGIZER
CONDITION CHECK
1. Determine Energizer condition. Test is not valid if
Energizer is not good and fully charged.
2. Connect a voltmeter from generator No. 2 terminal
to ground. If reading is zero, No. 2 lead circuit is
open.
3. If Energizer and No. 2 lead circuit check good, but
an obvious overcharge condition exists as evidenced
by excessive Energizer water usage, proceed as
follows:
a. Separate end frames as covered in Delcotron
“Disassembly” section in the Overhaul Manual.
Check field winding for shorts. If shorted replace
rotor and regulator.
b. Connect ohmmeter using lowest range scale
from brush lead clip to end frame as shown in
Step 1, Figure
8
C, then reverse lead connections.
c. If both readings are zero, either the brush lead
clip is grounded, or regulator is defective.
d. A grounded brush lead clip can result from
omission of insulating washer (Fig.
8
C),
omission of insulating sleeve over screw, or
damaged insulating sleeve. Remove screw to
inspect sleeve. If satisfactory, replace regulator
as covered in the Overhaul Manual.
GENERATOR OUTPUT TEST
To check the generator in a test stand, proceed as
follows:
1. Make connections as shown in Figure 9C, except
leave the carbon pile disconnected. Use a fully
charged Energizer or battery, and a 10 ohm resistor
rated at six watts or more between the generator
No. 1 terminal and the Energizer.
2. Slowly increase the generator speed and observe the
voltage.
3. If the voltage is uncontrolled with speed and
increases above 16 volts, check for a grounded
brush lead clip as covered under heading of
“OVERCHARGED ENERGIZER”, Step 3. If not
grounded, replace the regulator.
NOTE: The Energizer must be fully charged
when making this check.
4. Connect the carbon pile as shown.
5. Operate the generator at moderate speed as
required and adjust the carbon pile as required to
obtain maximum current output.
LIGHT DUTY TRUCK SERVICE MANUAL