ENGINE-ELECTRICAL 6Y-10
a. 12-1/2 volts or more, turn off electrical loads,
stop engine and proceed to Step 7.
b. Less than 12-1/2 volts, perform "Delcotron Out
put Test-Ammeter Method” .
(1) Delcotron tests bad-refer to "The Overhaul
Manual” and repair Delcotron, then repeat
Step 6.
(2) Delcotron tests good - disconnect regulator
connector, remove regulator cover and re
connect the connector. Then repeat Step 6 and
turn voltage adjusting screw (fig. 3c) to raise
setting to 12-1/2 volts. Turn off loads, stop
engine and proceed to Step 7. If 12-1/2 volts
cannot be obtained, install a new regulator and
repeat Step 6.
Adjusting Regulator Voltage
7. Connect a 1/2 ohm-25 watt fixed resistor (purchased
commercially) into the charging circuit at horn relay
junction block as shown in Figure 4c.
NOTE:
Between both leads and the terminal.
8. Run engine at 1500 rpm or above for at least 15
minutes of warm-up, then cycle regulator voltage
control (by disconnecting and re-connecting regulator
connector) and read voltage.
If voltage is 13.5 to 15.2 the regulator is okay.
a. Disconnect four terminal connector and reinstall
regulator cover. Then re-connect four terminal
connector and adjust voltage to 14.2 and 14.6
(Refer to Step 6 and fig. 3c).
b. Disconnect four terminal connector and reinstall
regulator cover, then reinstall connector.
c. Continue running engine at 1500 rpm for 5-10
minutes to re-establish regulator internal tem
perature.
d. Cycle regulator voltage by disconnecting and re
connecting regulator connector. Read voltage. A
reading between 13.5 and 15.2 indicates a good
regulator.
CAUTION:
Be_ sure four terminal regulator con
nector is disconnected when removing or install
ing cover. This is to prevent regulator damage
by short circuits.
SYSTEM CO M PO NENT TESTS
Delcotron Output Test— Ammeter Method (Fig. 5c)
1. Disconnect the battery ground cable at the battery.
2. Disconnect the red wire at Delcotron battery ter
minal and connect an ammeter in series between the
wire and terminal.
3. Connect a voltmeter from battery terminal to a good
ground on the generator.
4. Disconnect the F-R terminal connector at the Del
cotron.
5. Connect the jumper wire between Delcotron " F ” and
battery terminals.
6. Connect the battery ground cable at the battery.
7. Connect an adjustable carbon pile across the battery
posts.
8. Start the engine and slowly bring the speed to 1500
rpm and at the same time adjust the carbon pile load
to hold the voltage at 14 volts.
9. Read the amperage and compare with a specifications
chart.
10. Turn off ignition, disconnect battery ground cable,
and remove all test equipment.
11. If the Delcotron meets the test specifications, the
problem is not in the generator.
12. If the Delcotron fails to meet the test specifications,
remove it and perform bench tests and make repairs
needed.
Delcotron Diode and Field Test (Fig. 6c)
NOTE:
These tests will indicate good, shorted
or open field or shorted diode but will not indi
cate a failed open diode. If output was low and
following tests show good, refer to service opera
tions to determine cause and repair.
1. Disconnect battery ground cable at battery.
2. Positive diodes (Test A) - connect an ohmmeter be
tween " R ” and "BAT” terminal and note reading,
then reverse the leads at same terminals and note
this reading. Meter should read high resistance in
one direction and low in the other.
c u L J
Fig. 5c-Am m eter Method Output Test Connection
Fig. 6c -D e lcotron Diode and Field Tests
10-30 CHEVROLET TRUCK SERVICE MANUAL
Summary of Contents for 10 1971 Series
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