1953 JEEP DJ oil type

H

ELECTRICAL
SYSTEM
colder plug may be desirable. However, under- or
over-heating is usually caused by factors other than the type of
spark
plugs and the cause should be determined before changing plugs. The design of the
engine
calls for plugs equivalent to Champion

J-8
for F4
engines
and
A.C.
44S or
UJ12Y
Champ­

ion for the V6 engines, (as installed in production)
though any factor that consistently affects
engine
operating temperature may cause this requirement
to change. Overheating may be caused by in­ sufficient tightening of the plug in the head, which interferes with the flow of heat away from the firing

tip.
If this is the case, the plug gasket
will
show very
little flattening. Over-tightening, in
turn,
will
pro­ duce too easy a heat flow path and result in cold
plug operation.
This
will
be evident by excessive
flattening
and
deformation of the gasket.
Prevailing
temperatures, condition of the cooling system, and

air-fuel
mixture can affect the
engine
operating temperature and should be taken into consideration.
H-34.
GENERATOR
— F4
ENGINE

The
generator is an air-cooled, two-brush unit

which
cannot be adjusted to increase or decrease output. For replacement,
voltage
regulator and generator must be matched for
voltage
and capa­

city,
polarity, and common source of manufacture.
Otherwise,
either a
loss
of ampere capacity or a

burned
out generator
will
result. Generators for

these
vehicles are 12-volt. Par. H-l explains the 12-volt system. Refer to the specifications at the
end of this section for information on correct generator rating for a specific model series.
The
circuit
breaker,
voltage
regulator, and current-

limiting
regulator are built into one combination

unit.
Because the regulator and battery are part
of the generator
circuit,
the output of the generator
depends upon the
state
of charge and temperature
of the battery.
With
a discharged battery, the
output
will
be high, decreasing proportionally as the battery
becomes
charged. For service informa­
tion covering current regulator see Par. H-41.

H-36.
Generator
Maintenance

A
periodic inspection should be made of the charg­
ing
circuit,
Fig. H-l9. The interval
between
these
checks
will
vary
depending upon type of service.
Dust,
dirt
and high speed operation are factors 10541

FIG.
H-19—CHARGING
CIRCUIT

1—
Battery
4-—Starter Switch

2—
Voltage
Regulator 5-—Charge Indicator

3—
Generator
which
contribute to increased wear of bearings

and
brushes.

Under
normal conditions a check should be made
each 6000 miles
[9.600
km.].

A
visual inspection should be made of all wiring,
to be sure there are no broken or damaged wires.

Check
all connections to be sure they are tight and

clean.

Should
the commutator be rough or worn the
armature
should be removed and the commutator

turned
and undercut. See Par. H-37.
The
brushes should slide freely in their holders.

Should
they be oil soaked or if they are worn to

less
than one-half their original length they should
be replaced. When new brushes are installed they should be sanded to provide
full
contact with the
commutator. Generators should not be checked for
output until the brushes are seated.

Brush
spring tension is important. High tension causes
rapid
brush and commutator wear while
low tension causes arcing and reduced output.
Test
the tension with a spring scale.
Check
the
specifications section at end of this section for

correct
spring tension for generator in question.
H-36.
Generator Disassembly
•
Refer to Fig. H-20:
Before beginning disassembly of the generator to

correct
electrical system malfunctions proceed with
inspection and
test
procedures as detailed in Par.

H-46
thru
H-62. If it is definitely determined that trouble exists within the generator, which ne­cessitates dismantling, proceed as follows. Remove the two frame screws in the commutator
end plate and remove the end plate assembly. Next
pull
the armature and drive head complete

from
the generator housing. Remove the generator pulley from the armature by removing the nut

and
washer. Do not
lose
the Woodruff key when
the pulley is removed. After this, remove the drive
end head assembly which includes the oil seal and
bearing.
To remove the bearing, remove the three
screws and lockwashers in the grease retainer and remove the retainer and felt washer, after which,
remove the bearing, oil guard and felt washer.
H-37.
Armature

If
the commutator is rough or worn,
turn
it down

in
a lathe. After turning, the mica insulation be­ tween the
segments
should be undercut to a depth of 34* [0,8 mm.].
To
test
the armature for a ground, connect one

prod
of a
test
lamp to the core or shaft (not on

bearing
surface) and touch each commutator
seg­
ment with the other prod. If the lamp lights, the

armature
segment
is grounded and the armature must be replaced.

To
test
for short in armature coils, a growler,

Fig.
H-21, is necessary. Place the armature on the growler and lay a thin steel strip on the armature

core.
The armature is then rotated slowly by hand

and
if a coil is shorted, the steel strip
will
vibrate.

Should
a coil be shorted the armature must be
replaced.

If
precision
test
equipment is available, the cus­

tomary
accurate
tests
can be made in accordance 188

H

ELECTRICAL
SYSTEM

FIG.
H-21—GROWLER
end so it rests on the pulley with the commutator
end up.

While
holding brushes clear of commutator with
the thumbs, place generator housing and field coils assembly in position, turning front end

bracket
so the dowel pin in housing enters
hole
in
end head. Place commutator end plate on shaft

and
install long frame screws.

When
reinstalling the generator on the engine, the

bracket
bolt torque wrench reading is 25 to 35 lb-ft. [3,4 a 4,8 kg-m.].

H-41.
CURRENT-VOLTAGE REGULATORS •
F4 Engine

H-42.
Description and
Operation
For
replacement,
voltage
regulator and generator must be matched for
voltage
and capacity, polarity,

and
common source of manufacture. Otherwise,
either a
loss
of ampere capacity or a burned out generator
will
result.

These
regulators are used with shunt-type gen­

erators
and have three units each with a separate function to perform. These units are the circuit

breaker
unit, the
voltage
regulator unit, and the

current
limiting regulator unit.

H-43.
Circuit
Breaker

It
consists of
an
electromagnet and a set of contacts.

The
contacts are mounted with one on a stationary

bracket,
and the other on a movable armature

which
is controlled by the electromagnet. The movable contact is mounted on a spring arm so that as the contacts open and
close
a slight wiping
action is produced.

The
electromagnet of the circuit breaker has two
windings, one, the shunt coil which is connected across the generator output like a voltmeter and
the other a series coil connected in series with the
generator output like an ammeter.These two coils

are
wound in the same direction so that when the
generator is charging the battery, the magnetism
of the series coil increases the total magnetism.

When
the battery discharges back through the generator, the magnetism of the series coil is re­ versed and the magnetism of the two coils is
opposed.
This
results in a decreased
pull
on the

armature
and spring action
opens
the contacts.
10240

FIG.
H-22—PRESTOLITE VOLTAGE REGULATOR
1—
"ARM"
Terminal

2—
"FLD"
Terminal

3— "BAT"
Terminal
The
sequence of operation of the circuit breaker is
as follows:

When
the generator is not running, the contacts
are
open. When the generator is started, the
voltage
builds up at the armature terminal and in the shunt

coil
and as
soon
as it reaches the value for which
the circuit breaker is calibrated, there is sufficient magnetism created by the shunt coil to
pull
down
the armature, closing the contacts which auto­
matically
connects the generator to the battery.

With
the contacts thus closed the current in the
series coil is flowing from the generator to the battery or in the same direction as the current in
the shunt coil, so that the
pull
on the armature is

increased
by the magnetism of the series coil.

When
the
engine
is stopped and the generator
loses

speed, the
voltage
falls, and as
soon
as the gener­
ator
voltage
drops below the battery terminal vol­
tage,
the current flows from the battery to the generator, reversing the direction of current in the
series coil so that the magnetism created by the series coil
opposes
and reduces the magnetism of
the shunt
coil.
This
reduces the
pull
on the
armature

to a point where spring action
opens
the contacts.

H-44.
Voltage
Regulator

The
function of the
voltage
regulator is to hold
the generated
voltage
at a predetermined value as 190

'Jeep*
UNIVERSAL SERIES SERVICE
MANUAL

H
long as the circuit values allow the voltage to build
up to the operating voltage.
The
electromagnet of the voltage regulator unit has

a
winding of many turns of fine wire and is con­
nected across the charging circuit so that the sys­ tem voltage controls the amount of magnetism.
The
contacts of the voltage regulator unit are con­
nected in the generator field circuit so that the field

circuit
is completed through the contacts when they

are
closed and through a resistor when the contacts
are
opened.

When
the voltage rises to a predetermined value
there is sufficient magnetism created by the regu­

lator
winding to
pull
the
armature
down.
This
opens

the contacts and inserts resistance in the field
cir­

cuit
of the generator thus reducing the
field
current.
The
generated voltage immediately drops, which
reduces the
pull
on the
armature
to the point where
the spring closes the contacts. The output again

rises
and the cycle is repeated.

These
cycles occur at high enough frequencies to
hold the generated voltage at a constant value and

will
continue as long as the voltage of the circuit
is high enough to keep the voltage regulator unit

in
operation.
With
the addition of a current load great enough to lower the battery voltage below
the operating voltage of the unit, the contacts
will

remain
closed and the generator
will
maintain a
charging
rate as limited by its speed or the current

limiting
regulator.

Due
to the
effect
of heat on the operating
charac­

teristics of regulator windings it is necessary to
compensate for the changes in coil resistance when
the regulator is operating under varying tempera­

ture
conditions.
This
is accomplished through the
use of a nickel iron magnetic by-pass on the volt­
age regulator unit.
This
shunt by-passes
some
of
the magnetic flux when the unit is cold and allows most of the flux to act on the armature when the

unit
is hot.
Thus
when the coil is hot and not as
efficient, the magnetic shunt reduces the amount of flux needed to vibrate the armature.

The
compensation is usually more than enough to

offset
the changes in regulator coil resistance due
to heat. The excess compensation allows the regu­

lator
to operate at higher voltage under cold
operating conditions than under hot conditions.
This
is necessary as it requires a higher voltage to charge a battery with its internal resistance in­

creased
by low temperatures.

H-45.
Current-Limiting
Regulator

The
function of the current-limiting regulator is to limit the output of the generator to its maxi­

mum
safe output.

The
electromagnet of the current regulator unit
consists of
a
winding of heavy
wire
that is connected
in
series with the generator output. When the gen­

erator
output reaches a predetermined value, the
current
in the winding produces enough magnetism
to overcome the spring tension and
pull
the
arma­
ture
down.
This
opens
the contacts and inserts re­
sistance in the field circuit of the generator.
With
the field current reduced by the resistance, the
generator output falls and there is no longer enough
magnetism to hold the contacts open. As soon as
the spring closes the contacts, the output rises and the cycle is repeated. These cycles occur at high
enough frequencies to limit the output to a mini­
mum
fluctuation.

H-46.
Preliminary Inspection

a.
Wiring—Check
the wiring to see that it is prop­
erly
connected to the generator.

b.
Generator
Performance—Make
sure the genera­
tor operates correctly without the regulator in the
circuit.
Remove the armature and battery leads

from
the regulator and connect an ammeter be­
tween them. Remove the field lead from the regu­

lator
and while operating at idle speed touch the
field
lead
to the regulator base. Increase the speed slowly noting the charging rate.

CAUTION:
Do not increase the output above
the rated output of the generator.

If
the generator output
will
not build up inspect
the wiring harness for shorts and
opens
and remove the generator for an overhaul. To check the genera­
tor circuit when a suitable ammeter is unavailable,

Fig.
H-19, disconnect the armature cable at the

regulator.
Connect one lead of
a
12v
test
lamp to the regulator terminal marked "armature" and with
the engine running, ground the other lead. Should
the
test
light
fail
to
burn
there is a fault either in the generator or regulator. To localize the fault, discon­
nect both the
"Field"
and
"Armature"
cables at the generator. Connect a wire from the
"Field"
ter­
minal
to ground and use a 60 watt, 110 volt
test

lamp
to ground the
"Armature"
terminal. If the
generator is charging satisfactorily the
test
lamp

will
glow
at approximately 1500 rpm. engine speed
and
the fault
will
be definitely localized in the
regulator.

c.
Incorrect Regulator—Make sui he regulator
is the correct type for use with the generator.

d.
Battery—Check
the specific gravity and termi­

nal
voltage of the battery. If the \ ttery is not up
to specifications substitute temporarily
for
test
pur­
poses
a fully charged battery of the same type and
capacity.

e. High Resistance Connections—Inspect the
wir­
ing between the generator, regulator and battery for broken wires and high resistance connections.

Pay
special attention to the ground connections at
all
three units. Connect a reliable ammeter with 1-ampere graduations in series with the regulator

B-terminal
and the lead removed from this
terminal.
Run
the generator at a medium speed and
turn
on the lights or accessories until the ammeter shows a 10-ampere charging rate. At this charging rate
measure the voltage drop between the following
points using an accurate voltmeter graduated in
,1-volt divisions. The voltmeter should not show

a
reading above the maximum noted.
Generator
"A" terminal to regulator
"A"
terminal
—.1-volt maximum.

Generator
"F"
terminal to regulator
"F"
terminal
—.05-volt maximum.

Battery
terminal to regulator "B" terminal— .1-volt maximum.

Regulator
ground screw to generator frame— .03-volt maximum. 191

H

ELECTRICAL
SYSTEM
FIG.
H-38—WIRE
COLOR CODE
AND

LOCATIONS
FOR
ALTERNATOR HOOK-UP

1— Regulator (Auxiliary)
Terminal
(Cable —
Grey)

2— Output
Terminal:
(Red)

3—
Regulator
Terminal
(Cable —
Grey)

4—
Ground
Terminal
(Cable — Black-White
Tracer)
5—
Field
Terminal
(Cable — Green-White
Tracer)

6—
Ground
(Optional)
Terminal
(Cable — Black-White
Tracer)
REAR
VIEW

35
AMP.
ALTERNATOR
REAR
VIEW
40
& 55 AMP.
ALTERNATOR
given in Par. H-78, adjusting the fan belt to its
proper tension after the alternator is mounted, as described in Par. C-27. Wires should be connected
as shown in Fig. H-38.

When
the vehicle is equipped with a radio, a .55
mfd. capacitor is required on the alternator. Mount
the capacitor strap to a ground terminal and con­
nect the lead to the output terminal.
H-88.
STARTING
SYSTEM
SERVICE
H-89.
Ignition
Switch

The
ignition switch serves both to energize the
ignition system and
engage
the starter switch.
The
ignition switch has four positions: (1) AC­

CESSORY,
(2)
LOCK,
(3) ON, and (4)
START. The
key must be in the switch to turn it to any position other than
LOCK,
and the key can be
removed only in the
LOCK
position.
In "ACC",
a connection is made from the battery

terminal
to the accessory terminal of the switch to
allow accessories such as the radio, blower and/or
windshield wiper to be operated with the ignition, fuel
gauge
and indicator light circuits off.
In "LOCK",
no accessory supplied through the
ignition switch can be operated. Also, the ballast
resistor (V-6
engine
only) circuit to the ignition
coil
(IGN) is grounded.
In
"ON", a connection is made from the battery

terminal
to the accessory terminal so that all
ignition switch supplied accessories can be operated. Also the battery is connected to the ballast resistor
(V-6
engine
only) leading to the ignition coil

(IGN).
From
this same terminal, a lead
into
the
instrument cluster energizes the fuel
gauge
and
indicator lights.
In "START",
all ignition switch supplied acces­
sories are temporarily disconnected. A connection is made to the starter solenoid lead. The charge

and
oil indicator lamps
will
light until the
engine
is started.
H-90.
Ignition
Switch
Removal

a.
Remove the bezel nut and pull back the main
switch body.
Lower
the switch
body
from under the instrument panel so that the wiring harness plug

can
be removed from the prong connection,
b. If the lock cylinder is to be removed, turn the
ignition key to the right and insert a short
piece

of wire or end of a paper clip
into
the lock release

hole
in the switch body. Pressing on the lock
cyl­
inder retainer
will
allow the cylinder to be removed.
H-91.
Ignition
Switch
Installation

Before installing the lock cylinder
into
the main
switch body,
note
the position of the lock cylinder
retainer.

a.
Place the lock cylinder
into
the main switch
body
with the highest part of the lock cylinder
retainer in line with the lock release
hole
in the
main
switch body.
b. Compress the lock cylinder retainer so that the
lock cylinder can be installed all the way
into
the

main
switch
body
or until the retainer can be

seen
through the pin hole.

c.
Install
wiring harness plug
onto
switch
body

prong connection.

d.
Install
this main switch
body
into
the instru­
ment panel opening from the
rear.

e. To make sure that the switch is in its correct position, install the ignition key in the off position.
Then
turn the switch
body
until the key is straight
up and down. Remove the key, install the bezel
nut and secure.
H-92.
PRESTOLITE
STARTING
MOTOR
DAUNTLESS
V-6 and

HURRICANE
F4
ENGINE

The
Prestolite starting motor on the V6
engine
is

similar
in construction (with exception of pinion housings) to the starting motor installed on F4

engines.
The
starter solenoid switch is bolted to the starter
frame.

The
starter is equipped with
sealed-type
absorbent
bronze bearings and no lubricant is required. Service procedures for the Prestolite starter are
given in
Pars.
H-93 to H-107. 202

'Jeep*
UNIVERSAL
SERIES SERVICE
MANUAL

H
13406

FIG.
H-39—STARTING
CIRCUIT

1—
Ground
Cable
2—
Battery

3—
Positive Cable
4—
Alternator
Wire
5—
Alternator

6— Ignition Switch
Wire

H-93.
Maintenance Procedure

A
periodic inspection should be made of the start­ ing circuit. Since the interval
between
these
checks

will
vary according to the type of service, it should, under normal conditions, be made every 500 hours
of operation. Inspect all starting circuit wiring for damage.
Check
for
loose
or corroded terminals and
for dependable operation of the starting motor.

H-94.
Wiring

Refer
to Fig. H-39. Inspect the starting circuit to make sure that all
connections are clean and tight.
Check
for worn or damaged insulation on the wires. Perform a volt­

age-loss
test
to make sure there is no
loss
of start­ ing motor efficiency resulting from high resistance
connections. Voltage
loss
from the battery ter­
minal
to the starting motor terminal should not
exceed .30 volts for each 100 amperes. Voltage
loss
between
the battery ground
post
and the start­ing motor frame should not exceed .10 volts for
each 100 amperes. If the
voltage
loss
is greater
than
these
limits, measure the
voltage
loss
over
each part of the circuit until the resistance causing the
voltage
loss
is located and corrected.

H-95.
Commutator
Sluggish starting motor operation may be caused by a dirty commutator or worn brushes. The com­mutator cannot be cleaned while the. starting motor is mounted on the
engine
and it
will
be necessary
to remove it and proceed as for an overhaul. Should 7— Ignition Switch
8— Solenoid
Wire

9—
Starter

10— Solenoid
11—
Connector
Strap
the commuator be rough or worn, it should be
removed for cleaning and reconditioning.
H-96.
Overhaul Procedure

At
periodic intervals the starting motor circuit
should be thoroughly checked and the motor re­ moved from the
engine
for cleaning and checking.

H-97.
Removal and Disassembly

Refer
to Fig. H-40 and H-41.
To
remove the starting motor from the engine, dis­
connect the leads and cover the battery lead ter­

minal
with a piece of
hose
or tape to prevent short

circuiting.
Remove the flange
bolts
holding the starting motor to the flywheel housing. Remove
the starting motor from the vehicle.

Each
part of the starting motor should be removed, cleaned, and inspected for evidence of wear or
damage. The Bendix
Folo-Thru
Drive should be
cleaned and inspected for evidence of wear or a distorted spring. Bearings should be checked for
proper clearance and fit. All insulation should be
free of oil and in
good
condition. The armature,
field coils, and brushes should be checked for
good
ground and lack of open circuits.

H-98.
Brushes

a.
The brushes should slide freely in their holders
and
make full contact on the commutator. Worn
brushes should be replaced.
b.
Check
brush spring tension with a spring scale.
Hook the scale under the brush spring near the 203

H

ELECTRICAL
SYSTEM

FIG.
H-42—GROWLER
d.
Install
the armature in starter motor frame,
using care to align the four brushes and brush
springs on the commutator so that they are free to
move
and are square on the commutator.

e.
Install
the thrust washer on the shaft.
Lubricate

the plug and bearing in the end plate.
Install
the
end plate.
Install
the two through
bolts
and tighten securely.

f.
On Prestolite V6 starting motors, check pinion position by measuring from the centerline of the
pinion housing mounting bolt
holes
to the outside

edge
of the pinion.
Correct
measurement with the
Bendix
drive retracted is [19,05 mm.] to
%"
[22,23 mm.]; with drive extended, 1%"

[34,93
mm.] to 1^" [38,10]. Adjust by installing

thrust
washers just inside the commutator end
head or intermediate bearing as required. The
Bendix
drive retaining pin must not project
beyond the outside diameter of the pinion
sleeve.

H-104.
Bench Test

The
motor should first be checked to see that the
free running
voltage
and current are within specifi­ cations. To
test,
connect the motor to a battery,
ammeter and voltmeter. If the current is too high
check
the bearing alignment and end play to make

sure
there is no binding or interference. Using a

spring
scale and torque arm check the stall torque to see that the motor is producing its rated
crank­

ing power. The stall torque
will
be product of the

spring
scale reading and the length of the arm

in
feet.
If the torque is not up to specifications

check
the seating of the brushes on the commutator
and
the internal connection of the motor for high
resistance. The Bendix
Folo-Thru-Drive
should be checked for correct operation. The Bendix pinion
should be checked to see that it shifts when the motor is operated under no load.

H-105.
Bendix Folo-Thru Drive (Prestolite)
The
Bendix
Folo-Thru
Drive is designed to over­

come
premature demeshing of the drive pinion
from
the flywheel ring gear until a predetermined

engine
speed is reached. See Fig. H-43. No repairs or adjustments are possible on this

drive
and a
complete
new unit must be installed

if
trouble develops.

H-106.
Lubrication
of
Folo-Thru Drive
A
periodic cleaning and relubrication of the drive is advisable, the frequency of which
will
depend on
the type of service to which the vehicle is sub­
jected and the locale of operation.

a.
Remove the starting motor from the
engine
and take off the outboard housing. The pinion and

barrel
assembly
will
be in the demeshed position
on the screwshaft. Do not
move
it forward
until
after
that portion of the armature shaft ahead
of the pinion has been cleaned. If accidentally ro­
tated to the outer end of the screwshaft it
will

lock
in that position and cannot be forced back.

b.
Do not disassemble the drive for any reason.

c.
Do not dip or wash the drive in any cleaning solution.

d.
Do not remove the drive from the armature
shaft. Remove
excess
oil, grease or foreign matter
from
the armature shaft by wiping it with a clean cloth.
3
10859
FIG.
H-43—BENDIX
FOLO-THRU DRIVE

Dampen
the cloth with kerosene if necessary. A
light film of
SAE
10 oil may then be applied to the shaft.

e.
Now rotate the pinion and
barrel
assembly to the
fully
extended position, thereby exposing the screw­ shaft triple threads. Use a cloth dampened with
kerosene to wipe them clean. Do not use
gaso­
line
or any
commercial cleaner.
If the dirt is

thick
and gummy, apply the kerosene with a small

brush.
Tilt
the starting motor so that a small
amount
will
run under the control nut. Relubricate

with
a thin film of
SAE
10 oil. Use SAE 5 at ex­ tremely low temperatures.

f.
Reassemble the starting motor to the
engine
with the drive in the extended position.
Carefully
mesh the pinion with the flywheel ring gear before
tightening the starter motor mounting bolts. It may 206

'Jeep'
UNIVERSAL
SERIES SERVICE
MANUAL

H
Note:
Pinion clearance cannot be adjusted. If
clearance is not correct, motor must be disassem­
bled and checked for the above mentioned defects.

Any
defective parts must be replaced.
H-118. Starting Motor Test —
Genera!

To
obtain
full
performance data on a starting motor, or to determine the cause of abnormal
operation, the motor should be submitted to no-
load and locked armature
tests,
with equipment designed for such
tests.
A high-current variable resistance is required to obtain the specified volt­
age at the starting motor.
This
is necessary since
a
small variation in the
voltage
will
produce a
marked
difference in the current
drawn.

H-119.
Starting Motor No-Load Test

This
test
requires a DC voltmeter capable of
read­

ing
voltages
in a 12-volt
circuit,
a DC ammeter

with
maximum range of several hundred amperes,
a
high-current variable resistance, an rpm. in­

dicator,
and a fully-charged, 12-volt battery.

a.
Connect a jumper lead
between
S terminal
and
large battery terminal of starter solenoid.
Con­
nect voltmeter
between
either of
these
terminals (positive) and motor frame (negative, ground).

Connect
ammeter and variable resistance in series

between
positive terminal of battery and battery

terminal
of solenoid. Set up rpm. indicator to show starting motor speed.
b.
Initially,
adjust variable resistance to a value of
approximately .25 ohm. To complete the
circuit,

connect negative terminal of battery to motor

frame.
Adjust variable resistance to obtain a volt­ meter reading of 10.6 volts;
note
speed of starting motor and ammeter reading. Motor speed should
be
6750
to
10,500
rpm.; ammeter reading should
be 50 to 80 amperes.
c. Rated speed and current indicate normal condi­
tion of the starting motor. Low speed and high
cur­
rent
may show friction; this could be caused by
tight, dirty, or worn bearings, bent armature shaft,

or
a
loose
field
pole
shoe
dragging against the

armature.
It could also be caused by a short-cir­ cuited armature, or by grounded armature or field
coils.

d.
Failure
to operate and high current indicates

a
direct short circuit to ground at either the battery

terminal
or field coils.
e.
Failure
to operate and no current are usually
caused by broken brush springs, worn brushes, high insulation
between
commutator
bars,
or
some
other
condition preventing
good
contact
between
the brushes and commutator. It can also be caused by
open circuit in either the field coils or armature coils.
f. Low speed and low current show high resistance due to poor connections, defective leads, dirty com­
mutator, or one of the conditions mentioned in e,
above.
g. High speed and high current indicates a short
circuit
in the field coils. H-120-
Locked
Armature Test

This
test
requires a DC voltmeter with range ap­

propriate
to read
voltages
in a 12-volt
circuit,
a DC
ammeter with maximum range of several hundred
amperes, a high-current variable resistance, a
clamping fixture to lock
together
the motor shaft

and
case, and a fully-charged 12-volt battery.

a.
Connect a jumper lead
between
S terminal and
large battery terminal of starter solenoid. Connect
voltmeter
between
either of
these
terminals (posi­
tive) and motor frame (negative, ground). Connect
ammeter and variable resistance in series
between
positive terminal of battery and battery terminal
of solenoid.
Install
clamping fixture to lock motor
shaft and case
together
securely.
b.
Initially,
adjust variable resistance to approxi­
mately .05 ohm. To complete the
circuit,
connect
negative terminal of battery to motor frame. Ad­

just
variable resistance to obtain a voltmeter
read­
ing of 4.0 volts. Ammeter reading should be 280
to 320 amperes.

H-121.
Solenoid Starter Switch — Delco

The
solenoid-type switch is mounted directly on
the starting motor.
This
type of switch is energized
by turning the ignition key to the extreme right position. Should the solenoid switch
fail
in service

it
is necessary to install a new assembly.

Should
a starting motor
fail
to deliver maximum power the fault may be due to
voltage
drop at the

starter
switch contacts due to corrosion or burning.

Check
the switch by comparing the
voltage
at the
battery across the terminals. The
voltage
drop
should not exceed .05 volts per 100 amperes.
In
order to remove the starter solenoid, it is neces­

sary
to remove the starter assembly.

H-122.
ELECTRICAL
INSTRUMENTS

H-123.
Fuel
Gauge —
CJ-3B

The
fuel
gauge
circuit is composed of the indicating

unit,
mounted on the instrument panel, and the
fuel tank unit, connected by a single wire through the ignition switch.

Should
the
gauge
fail
to register, check all wire con­ nections to be sure they are tight and clean; also
be sure both units are well grounded. If, after this
check, the
gauge
does
not indicate properly, remove
the wire from the tank unit and connect it to a
new tank unit which must be grounded to the tank

or
frame for
test.
Turn
the ignition switch "ON"
and
move
the float arm through its range of travel,
watching the dash unit to determine if it indicates
correctly.
If it fails to do so the trouble is probably

in
the dash unit and it should be replaced.

Should
a new tank unit be unavailable for this
test,
disconnect tank unit wire at the instrument panel

gauge.
Connect one lead of a 12 V, 1 CP
test
light
to the instrument panel unit terminal and with the
ignition switch
"ON"
ground the other lead. If the
unit is operating correctly the pointer
will
move

approximately three-quarter across the
dial.
Do not attempt to repair either unit; replacement
is the only precedure. 211

H

ELECTRICAL
SYSTEM
H-124. Testing Indicators and Gauges

Two
gauges
(fuel and temperature) and two in­ dicators (oil pressure and battery charge) that are
located in the instrument cluster are electrically operated.

The
fuel
gauge
is connected by a single wire to a
float-and-slide-rheostat sending unit in the fuel
tank.

The
temperature
gauge
is connected by a single

wire
to a resistance-type sending unit mounted on the engine.

The
battery charge indicator operates when there
is a difference in potential
between
the generator
and
the battery
.The
battery charge indicator lights
when the generator is not charging the battery. The
indicator
light
goes
out when the generator
begins

to charge the battery.

The
oil pressure indicator is connected by a single

wire
to a diaphragm switch located on the engine.
When
engine
oil pressure is low or zero and the
ignition switch is on, the oil pressure indicator
will

light. When
engine
speed is increased slightly above idle speed, raising the oil pressure to approximately 6 psi. [0,2 kg-cm2], the diaphragm switch
will
open the circuit and the indicator light
will
go out.

A
voltage
regulator maintains a constant
voltage
to the
gauges
in normal operation. On early vehicles,
this
voltage
regulator was mounted on the
rear
of
the instrument cluster. On current vehicles, the
voltage
regulator is integral with the fuel
gauge.

Should
trouble
develop
in the
gauges,
first check the regulator (fuel
gauge
on current production vehicle). If the
voltage
to the regulator is below 10 volts system low
gauge
readings
will
result.
Voltage in
excess
of 16 volts
will
not affect
gauge

readings but may result in premature wear of the
regulator contacts. If the
voltage
to the regulator is

within
the above limits, check the electrical con­ nections to the regulator (or fuel gauge), especially
the ground connection. If the readings of all the
gauges
is too high, or they all read too low, replace
the regulator (or fuel gauge).

If
the temperature
gauge
or heat indicator in the
instrument cluster have failed, the cause may
originate from the jumper bar shorting out against the instrument case.
Check
the jumper bar
between

the temperature
gauge
and heat indicator at the

rear
of the instrument case. On later production vehicles, the jumper bar is covered with an in­
sulating
sleeve
to protect it from shorting out
against the instrument case. If the jumper bar

does
not have this
sleeve,
either install one or

wrap
the bar with plastic electrical tape to
half

an
inch [12,7 mm.] from each end. When installing the jumper bar, be sure the curved
segment
is
closest to the fuel
gauge.

Should
only one of the two
gauges
register incor­
rectly,
check the lead wire from the
gauge
to the
sending unit for shorts or open connections. Next disconnect the
gauge
from the sending unit, and
connect the
gauge
to a new fuel tank sending unit

which
has been grounded to the vehicle.
If
the
gauge
registers incorrectly when operating the new unit,
replace the
gauge;
if correctly, replace the sending

unit.

Should
a new fuel tank unit not be available for testing, use a 12-volt
test
light in its place. When
the
gauge
is operating correctly, the pointer
will

move
approximately three-quarters across the
dial.

On
some
vehicles, the temperature
gauge
may
register on or
close
to the H (hot)
mark
when
coolant temperature is
190°F.
to
200°F.
[88°C.
a

93°C.].
In such cases, a 25-ohm,
1-watt
resistor
may be installed on the temperature
gauge
which

will
place the pointer just beyond the center
mark
at a coolant temperature of
190°F.
to
200°F.
Install

the resistor
between
the two terminals on the back
of the
gauge.
Insulate the
exposed
leads of the resistor with electrical tape.

If
the oil pressure indicator
does
not indicate cor­

rectly,
first check the light bulb. Next check all
connections and lead wires. If, after all possible

defects
are corrected, the indicator light
does
not go on and off properly, then the diaphragm type
switch in the cylinder block should be replaced.

H-12S.
LIGHTING SYSTEM The
wiring of the lighting systems is shown in
the wiring diagrams, which indicate the various units in relation to their positions in the vehicle.
The
wires in the various circuits are of different
colors or are marked by tracers to aid when check­
ing individual circuits.

The
lighting circuits of all models are protected by

an
overload circuit breaker mounted on the back of the main light switch and no replaceable fuse is
required.

The
upper and lower headlight beams are con­
trolled by a
foot
switch located on the toe board
to the left of the clutch pedal.
H-126.
Main
Light
Switch

This
switch is a dual functioning unit having two

push-pull
positions and a rotary action. When
pulled out to the first position, the front parking
and
tail
lights are turned on. When pulled all the
way out to the second position, the headlights and
tail
lights are turned on. Rotating the switch to
the right dims the instrument cluster lighting.

The
switch may be removed from the instrument
panel by first loosening the set screw in the control
knob and removing the knob. The retaining nut may then be removed and the switch removed
through the
rear
of the instrument panel.
FIG.
H-51—MAIN
LIGHT
SWITCH
(EARLY)

1—
Battery
4—Parking Lights
2—
Rear
Lights 5—Auxiliary

3—
Head
Lights
212