Chevrolet 70 Series 1970, Service Manual

Page: 550 / 841

ENGINE ELECTRICAL 6Y-9
IMPORTANT
To prevent engine starting while p er­
form ing these checks, disconnect p rim a ry
lead at distributor on gasoline engine
models. On diesel engine models, pull
stop knob on instrum ent panel out to set
injector rgcks in NO F U E L position, or
disconnect w ire from full shut-off solenoid.
Figure
1 —Voltm eter Connections fo r Checking Circuits
STARTER REPLACEMENT
CHECK V -l (Fig. 1, View A)
Check V -l with v o ltm e te r lead s connected to
b a tte ry p o sitiv e (+) post and the b a tte ry te rm in a l
on the s t a r t e r solenoid. On v eh icles equipped with
a solenoid and a m agnetic sw itch, connect volt­
m e te r leads a s noted above, then connect vo ltm eter
lead s to b a tte ry p o sitiv e (+) p o st and th e b a tte ry
te rm in a l on the m agnetic sw itch.
CHECK V-2 (Fig. 1, View B)
Check V -2 with v o ltm e te r lead s connected to
b a tte ry te rm in a l and to m o to r te rm in a l on solenoid.
On vehicles equipped with a solenoid and a m ag­
netic sw itch, connect v o ltm e te r leads a s n o te d p re -
viously, then connect v o ltm e te r leads to b a tte ry
te rm in a l and to m otor te rm in a l on m agnetic sw itch.
CHECK V-3 (Fig. 1, View C)
Check V-3 with v o ltm e te r leads connected to
b a tte ry negative (-) p o s ta n d th e s ta r te r f ie ld f r a m e .
CHECK V-4 (Fig. 1, View C)
On vehicles equipped with a solenoid and a
m agnetic sw itch, check V -4 with v o ltm eter lead s
connected to m otor te rm in a l on m agnetic sw itch
and to b a tte ry te rm in a l on s t a r t e r solenoid.
If v o ltm e te r reading in any of the above checks
exceeds 0.5 volt, ex c essiv e re s is ta n c e is indicated
in the p a r t of the c irc u it being checked. Locate
and elim inate the cau se of excessive voltage drop
in th e se c irc u its in o rd e r to obtain m axim um effic­
iency fro m the sta rtin g sy stem . Cause of excessive
re s is ta n c e may be loo se, corrod ed, o r d irty con­
nections, o r fray ed cab les.
If s t a r t e r fa ils to cran k engine, f i r s t m ake
s u re b a tte ry is not disch arg ed , then check solenoid
o r m agnetic sw itch operation. If the solenoid fa ils
to o p erate, the tro u b le m ay be due to ex cessive
re s is ta n c e in the s t a r t e r control c irc u it. Check all
w iring and connections fro m ignition o r control
sw itch to solenoid fo r lo o se o r corro d ed connec­
tio n s. If the cause of excessiv e re s is ta n c e is not
ap p a ren t, connect a sh o rt jum per lead a c ro s s the
solenoid b a tte ry and sw itch te rm in a ls . If solenoid
o p e ra te s with jum per lead connected, tro u b le is in
the co ntro l c irc u it. Check fo r defective ignition o r
co n tro l sw itch. If solenoid does not o p erate with
ju m p er lead connected, solenoid o r m agnetic sw itch
is defective and m ust be replaced.
REMOVAL
1. Rem ove ground s tra p fro m b a tte ry negative
(-) po st o r tape end of b a tte ry cable when discon­
n ected fro m s t a r t e r solenoid to p re v en t d isch arge
of b a tte ry by d ire c t sh o rt.
2. D isconnect a ll w ire s fro m s t a r te r solenoid
te rm in a ls .
3. Rem ove b o lts, nuts, and w a sh e rs attaching
s t a r t e r to flywheel housing and pull s t a r t e r f o r ­
w a rd to rem ove.
INSTALLATION
1. On a ll v ehicles equipped with the T o ro -F lo w
D iesel engine, p osition s p a c e r between flywheel
housing and s ta rtin g m otor, then in sta ll s t a r t e r to
flywheel housing mounting bo lts and w a sh e rs. T ig ht­
en b olts to to rq ue recom m ended in "Specifications"
a t end of th is section .
On a ll o th er engine m odels, position s t a r t e r
ag a in st flywheel housing and s e c u re with b olts,
nuts, and w a sh e rs. Tighten s t a r t e r to flyw heel
housing mounting bolts o r nuts to torqu e re c o m ­
m ended in "Specifications" a t end of th is sectio n .
2. Connect a ll w ire s to s t a r t e r s o le n o id te rm -
in a ls re fe rrin g to p ro p e r w iring d iagram in ap p lic­
ab le "W iring D iag ram s" booklet to m ake s u re of
p ro p e r connections. Tighten te rm in a l nuts firm ly .
CHEVROLET SERIES 70-90 HEAVY DUTY TRUCK SHOP MANUAL