Chevrolet 30 Series 1967 Service Manual page 358

ENGINE-ELECTRICAL 6Y-10
4. Excessive generator noise or vibration.
Described below are a series of on-the-vehicle quick
checks which are designed to assist the service techni­
cian in locating troubles within the various components
of the engine electrical system. Additional checks, ad­
justments and overhaul procedures of these components
are also described in the " Charging System s-Service
Operations Section" and
necessary.
STATIC CHECKS
Before making any electrical checks, perform the
following static checks:
1. Check for loose fan belt.
2. Check for defective battery. (Refer to Battery.)
3. Inspect all connections, including the slip-on con­
nectors at the regulator and Delcotron.
NOTE: Do not short field to ground to check if
generator is charging since this will seriously
damage the charging system.
SYSTEM CONDITION TEST
(5.5"-6.2" DELCOTRON SYSTEMS)
This test is used to indicate the overall condition of
the charging system (both good and defective) and to
isolate the malfunctioning unit if the system is defective.
1. With ignition off, perform the prescribed Static
Checks outlined in this section. Then set hand brake
and shift transmission into neutral.
2. Connect a voltmeter from junction block on horn
relay to ground at regulator base.
CAUTION: Be sure meter clip does not touch
a resistor or terminal extension under regulator.
3. Connect a tachometer on engine.
4. Turn ignition switch to " ON" and check indicator
lamp. If lamp fails to glow, perform appropriate
tests and corrections (see Indicator Lamp Circuit
tests) before continuing test.
5. If lamp glows, start the engine and run it at 1500
rpm or above. Check indicator lamp. If lamp fails
to go out, perform appropriate test and corrections
(see Indicator Lamp Circuit tests) before continuing
test.
DO NOT TURN THIS NUT
UNDER ANY CONDITION
should be referred to as
ADJUSTING SCREW
(Turn To Adjust
Voltage Setting)
Fig . 6 c —Adjust V oltage Setting
NOTE: At this point a field circuit has been
established and any other problem will lie in
generator or regulator.
. Turn on high-beam headlights and heater blower
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motor to high speed, run engine at or above 1500
rpm (for a few minutes, if necessary) and read the
voltage on meter.
NOTE:
Voltage will not greatly exceed 12-1/2
volts until the battery develops a surface charge,
a few minutes generally, unless the battery is
severely discharged or is hot.
If reading is:
a. - volts or more, turn off electrical loads,
1 2 1 / 2
stop engine and proceed to step 7.
b. Less than 12-1/2 volts, perform " Delcotron Out­
put Test-V oltm eter Method."
(1) Delcotron tests bad - refer to " Service Op­
erations" and repair Delcotron, then repeat
Step .
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(2) Delcotron tests good - disconnect regulator
connector, remove regulator cover and re ­
connect the connector. Then repeat step
and turn voltage adjusting screw (fig.
raise setting to 12-1/2 volts. On transistor
regulator remove pipe plug (fig.
screwdriver into slot and turn clockwise one
or two notches to increase setting. Turning
counterclockwise decreases setting. For each
notch moved, the voltage setting will change
approximately .3 volt. 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
ADJUSTING REGULATOR VOLTAGE
7. Connect a 1/4 ohm-25 watt fixed resistor (purchased
commercially) into the charging circuit at horn relay
junction block as shown in Figure 7c.
NOTE: Between both leads and the terminal.
c) to
6
c), insert
6
.
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CHEVROLET TRUCK SERVICE MANUAL
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