Chevrolet CHEVY VAN G10 SERIES Service Manual page 224

SYSTEM COMPONENT TESTS
D elcotron O u tp u t Test— A m m e te r M e th o d (Fig. 5c)
1. D isconnect the b attery ground cable at the battery .
2. D isconnect th e red wire at D elcotron b attery term inal
and connect an am m eter in series betw een th e wire and
term inal.
3. C onnect a voltm eter from b attery term inal to a good
ground on th e generator.
4. D isconnect the F-R term inal conn ecto r at the D elcotron.
5. C onnect the ju m per wire betw een D elcotron " F " and
b attery term inals.
6
. C onnect th e b a tte ry ground cable at th e b attery .
7. C onnect an adjustable carbon pile across the b attery
term inals.
8
. S tart the engine and slowly bring the speed to 1500 rpm
an d at th e same tim e adjust th e carbon pile load to hold
th e voltage at 14 volts.
9. R ead the am perage an d com pare w ith a specifications
chart.
10. T u rn o ff ignition, disconnect b attery ground cable, and
remove all test equipm ent.
11. I f the D elcotron m eets th e te st specifications, the p ro b ­
lem is n o t in the generator.
12. I f the D elcotron fails to m eet the test specifications,
remove it and perform bench tests and m ake repairs
needed.
In d ic a to r L a m p /In itia l Field
E xcita tion C irc u it Tests
On standard m odels th e indicator lam p circuit provides
initial field ex citatio n (causing lam p to glow). The light is
cancelled by closing the field relay w hich applies b attery
voltage to b o th side o f bulb (bulb goes out).
The indicator light should glow w hen ignition sw itch is
" ON" and go o u t alm ost im m ediately w hen engine starts.
A m m eter equipped vehicles use th e same initial field excita­
tio n and control circuits as th e indicator lam p except the lam p
is om itted. The co n tin u ity tests on b o th ty p e vehicles can be
made as follows:
If Lam p Fails to Glow or A m m eter Fails to F u n ctio n the
Possible Causes a re :
1. F aulty bulb or bulb socket.
2. F aulty am m eter.
3. An open circuit in wiring, regulator, or field.
4. A shorted positive diode— (m ay also cause glow w ith
ignition sw itch " O F F " ).
Fig. 6 c —In itial Field E xcitation C ircuit Tests
ENG INE E LE C TR IC A L 6Y-13
C H E V Y V A N SH O P M A N U A L