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85)
ELECTRICAL SYSTEMS
TROUBLE
DIAGNOSIS
10 -9
out
relay (par. 10-29)
.
A high closing voltage
will cause drive pinion clash.
3. If battery and cutout relay are up to speci-
fications, test
cut-in
and cut-out voltages
of
solenoid swich relay (par.
10-38)
.
4. If
source
of trouble has not been found,
check accelerator vacuum switch timing (par.
10-32 or
10-33).
Clash of
drive
pinion
from
this
cause
usually
occurs while driving
at low speed
rather th
an
on in
itial
sta
rts.
d.
Delayed
Di
seng a gem ent of Drive
Pinio n
Delayed
disengagement of drive pinion from
flywheel ring gear can be identified by a "zoom-
ing" sound as cranking motor is speeded up by
the
engine.
This condition may be caused by
dirty
gen erator
commutator and brushes, oxi
-
dized volt ag e regulator contact points, sticking
sol
enoid
plunger or cranking motor
drive
as-
sembly,
or by a
weak
shift
lever
return spring.
1.
Inspect gen erator
commutator and brushes
and
clean
if dirty (par. 10-26)
.
2.
Inspect
voltage regulator contact points
and clean if oxidized or pitted (par.
10-30).
3. If
solenoid
plunger or cranking motor
drive
assembly is sticking, or shift lever r
eturn
spring is
weak,
cranking motor must
be r
e-
mo
ved
so that these parts may be
properly
in-
spected
and
cleaned .
See paragraph
10-39
(c)
for pinion
travel adjustment
and
pa ragraph
10-41 (b) for test of shift lever
retur n
spring.
10-10
IGNITION SYSTEM-TROUBLE
DIAGN OSIS
If engine trouble has arisen which
seems
to
be du
e
to improper operation of
the
ignition
system,
it may
be
desirable to make a quick
preliminary
ch
eck
of the
ignition
system before
making a
complete analysis,
in order to
deter-
mine
whether the
ignition
system
is actually at
fault. The quick checks described in this para-
graph may be used but it must be understood
that they are no substitute for the complete
ignition system inspection (par. 10-44) that
sho uld be used if it
appears
that ignition is
f
aulty. The
ch
ecks
to
be
made depend on
whether the
engine will or will not run.
a. Engine Will Not Run
1. Make qui
ck
check of battery and cables
(par. 10-7)
if
cranking motor does not turn en-
gine a
t normal cranking sp
eed.
2. Pull coil high tension cable from dis-
tributor cap and hold
the lead
terminal about
:%
6"
from a clean ground point on engine. If a
good
spark
occurs while engine is being
cranked,
the primary circuit and the secondary circuit
to th is point may be considered to be okay. Pro-
ceed with steps 3 through
6.
3. Re
move
distributor cap and check
inte-
rior fo
r
moist ur e, corroded
terminal
segments,
and check terminal sockets for corrosion. Check
rotor for corrosion. Clean off corrosion and
wipe distributor cap dry (par. 10-44)
.
4. Remove spark plug cover and
inspect
ignition cables for possible short circuits and
corroded
terminals.
Remove and inspect spark
plugs (par. 10-48).
5. If
cause
of
trouble
has not been found,
check centrifugal and vacuum advance
mechan-
ism (par. 10-44) and check ignition timing
(par. 10-47).
6.
If engine still fails to run,
the
trouble
is probably
du
e
to causes other than ignition,
such as lack of fuel, carburetion, or compres-
sion loss.
7.
If
spark
did not occur at coil high
ten-
si
on
lead
(step
2, above) then observe charge
indicator while cranking engine. A small fluc-
tuating reading indicates that the primary
cir-
cuit is
probably
okay. Check ignition coil
(par.
10-49) and ch
eck condenser
(par. 10-50).
8. If
charge
indicator does not register any
r
eading while
eng ine is
being
cr a nk ed, the
primary
ignition
cir cuit is
open. Check for loose
connections, broken leads, defective
switch, dis-
tributor contact points not making
contact,
and
open
primar y winding
in coil
(par.
10-49).
Vis":
ual
inspection
of points and the us
e
of a test
lamp or
voltmeter
will
locate
the source of this
trouble.
9. If
charge
indicator shows a
steady
read-
ing of
several a
mper es while
engine
is being
cranked, then the primary
circuit is not being
interrupted by t
he
contact
points in
the
normal
manner. Ch
eck contact
p
oint
adjustment
(par.
10-4
5) .
If
t
he y
are
properly adj usted check
primary circuit for ground in wiring, conden-
ser (par
.
10-50 )
or coil
(par.
10-49)
.
b. Engine Runs,
But
Not
Sa tisfactorily
1. When missing, loss
of
power, or hard
starting is
present
a
complete
ch
eckup
of the
ignition
system
is in
order,
since
these
condi-
tions may
r
esult
from
anything from a
low bat-
t
ery
to
defective
spark
plugs,
or from other
engine conditions not
related
to ignition. In this
case,
the
complete
periodic inspection of igni-
tion system given in paragraph
10-44
should
be used.
2. Detonation may
be
caused by improper
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