1953 JEEP DJ key battery

H

ELECTRICAL
SYSTEM
the condenser. Replace the condenser. If there is
no jump to full voltage, overhaul or replace the

distributor.

k.
With the points closed, connect the voltmeter

from
a clean, paint-free
post
on the distributor
body to the negative
post
of the battery. The volt­
age drop should be practically zero, a hardly
readable deflection on the voltmeter. If the volt­ meter registers a
voltage
drop, perform the checks

in
steps
1
and m following.

I.
Check
for
voltage
drop in the battery ground
cable.
Clean
the battery
post,
cable terminals, and contact surface on the bellhousing, or on body if

a
noticeable deflection of the voltmeter occurs,
m.
Check
for any
voltage
drop
between
the dis­

tributor
body and a clean, paint-free
spot
on the

cylinder
block. If there is any
voltage
drop, remove
the distributor and clean the mounting surfaces of
distributor
body and cylinder block.

H-5.
SECONDARY
CIRCUIT
If
satisfactory ignition is not obtainable with cor­

rect
point gap and tension; satisfactory condenser;
sufficient primary voltage; and correctly cleaned, gapped, and installed spark plugs; the secondary

circiut
should be investigated.

a.
Test the coil.
Bring
the coil up to operating
temperature using the coil heat feature of a coil tester, if available. Refer to the coil tester manu­

facturer's
instructions for specific hook-ups for
performing the checks given in
steps
b, c, and d following.
b. Connect the positive lead of the tester to the
battery terminal of the coil primary winding.
Con­
nect the tester ground lead to the coil tower. Mea­

sure
the resistance of the secondary winding. If the
resistance is more than
20,000
ohms, a fault in the
secondary winding is indicated.
c.
Check
for a grounded secondary by touching the tester ground lead to the coil cover. If resistance
is not over
100,000
ohms, the secondary is grounded
to the cover.

d.
If the secondary winding is satisfactory, mea­
sure
the primary current draw in accordance with
the instructions of the
test
equipment manu­
facturer.

e.
Check
the secondary circuit for leakage. With the coil primary in the circuit with the breaker unit of the tester, connect a long, high-tension
test
lead
to the coil tower.
Check
the secondary circuit for
leakage by performing the checks given in
steps
f. g, h, and i following.

Note:
In the following
tests,
a slight sparking and
meter deflection
will
usually be
seen
just as contact
is made.
This
is caused by capacitance and
does
not
indicate defective insulation.
f.
Check
distributor cap. Remove the coil lead from the cap and touch the
test
lead to the center contact
inside the cap. If the meter reading drops when the contact is touched or if sparking is seen, a leakage
path is present
between
the center contact and one
of the plug towers.
This
leakage path
will
be in the

form
of a
crack
or carbon track in the cap. Discon­ nect the spark plug wires from the cap one at a
time and
test
each plug contact with the high-
voltage
lead and with all other plug wires con­
nected. Any sparking or meter drop indicates that

a
leakage path exists
between
that particular con­
tact and an adjacent one. Testing the adjacent contacts
will
determine which pair is at fault,
g-
Check
distributor rotor. Touch the
test
lead to
the spring contact in the center of the distributor
rotor.
Any leakage in the rotor insulation
between

the contact and the shaft
will
cause a drop in the meter reading and usually sparking
will
be seen.

h.
Check
spark plug wires. Disconnect the spark
plug wires from the plugs and
test
the plug terminal of each. The meter reading should not drop below
the open secondary value (value before making contact). If it
does
or if a large spark occurs when
the
test
lead and the plug wire are separated, there
is a break in the insulation on that wire.

i.
Check
the coil tower insulation. Remove the
high-tension
test
lead from the coil tower and touch
the ground lead of the coil tester to several points

around
the base of the tower. Any sparking or deflection of the meter indicates a leakage path in
the tower insulation.

H-6.
Alternator Charging System

All
Jeep
Universal
Series vehicles have, as standard
equipment a 35-amp., 12-volt, negative ground
alternator and a transistorized
voltage
regulator.
For
repairing the alternator, many of its major components are furnished as complete assemblies

including:
complete brush assembly which requires no soldering or unsoldering of leads; two complete
rectifying
diode
assemblies which eliminate the need for removing and replacing individual diodes;

a
complete isolation
diode
assembly; and a rotor assembly complete with shaft,
pole
pieces, field coil,

and
slip rings.

The
transistorized
voltage
regulator is an electronic
switching device. It
senses
the
voltage
appearing at the auxiliary terminal of the alternator and
supplies the necessary field current for maintaining the system
voltage
at the output
terminal.
The out­
put current is determined by the battery electrical

load;
such as headlights, heater, etc.
The
transistorized
voltage
regulator is a sealed unit,
has no adjustments, and must be replaced as a
complete unit.

H-7.
Starting System

The
operation of the starter motor is controlled by
the ignition switch. The starter is made up of a
frame,
field coil, armature, and brushes.

The
starter solenoid electrically
closes
the circuit

between
the battery and the starter motor. When the ignition key is turned to its extreme right, the
solenoid is energized and
closes
the battery-to- starter-motor circuit.

Note:
All Jeep Universal Series vehicles have the

starter
solenoid switch secured to the starter motor
assembly. The Hurricane F4 and Dauntless V-6

engine
Prestolite starter drive is of the inertia type
(rexr
continued on
page
176) 174

H

ELECTRICAL
SYSTEM
11474

FIG.
H-3—WIRING
DIAGRAM—MODELS
CJ-5, CJ-6, DJ-5 AND DJ-6—F4
ENGINE
(Model CJ-5 after Serial No.
49248,
Model CJ-6 after Serial No.
12577)

1—
Left
Headlamp
B—Turn
Signal Indicator 17—Directional Signal Switch
2—
Left
Parking and Directional Lamp C—Instrument Lights 18—Light Switch
3— Right Parking and Directional Lamp
D—Oil
Pressure Indicator
19—Stop
Light Switch
4— Right Headlamp E—Charging Indicator 20—Foot Dimmer Switch
5— Battery Ground Cable F—Temperature Gauge 21—Directional Signal Flasher
6— Generator
G—Fuel
Gauge 22—Fuse 7— Distributor H—Instrument Voltage Regulator
23—Solenoid
Switch
8— Ignition
Coil
12—Right
Tail
and
Stop
Lamp 24—Temperature Sending Unit
9— Starting Motor 13—Left
Tail
and
Stop
Lamp 25—Oil Pressure Signal Switch
10— Voltage Regulator 14—Fuel Gauge
Tank
Unit 26—Horn
11— Instrument Cluster 15—Ignition and Starter Switch 27—Junction Block
A—Upper
Beam Indicator 16—Horn Button
whereas the Dauntless V-6
engine
Delco starter
ignition
switch. If trouble
develops
in this switch, drive is of the clutch
type.
it must be replaced.
The
ignition
switch
serves
both
to
energize
the

The
starter circuit is
opened
when the
ignition
key
ignition
system
and
also
to
engage
the starter
sole-

is allowed to return to the "Ignition On"
position.
miod switch. With the key in the vertical
position,
No repairs or adjustments can be
made
to the the electrical
system
is off. This is the
only
position
176

'Jeep*
UNIVERSAL
SERIES
SERVICE
MANUAL

H

12968
FIG.
H-4—WIRING
DIAGRAM—MODELS
CJ-5, CJ-6, DJ-5, DJ-6
LATE
F4
ENGINE

1—
Left
Headlamp
2—
Left
Parking and Signal Lamp
3— Right Parking and Signal Lamp 4— Right Headlamp
5— Generator
6— Ignition Distributor
7—
Oil
Pressure Sending Unit
8— Junction Block
9—
Horn

10— Foot Dimmer Switch 11—
Stop
Light Switch — Front
12— Temperature Sending Unit
13— Ignition
Coil

14— Starting Motor 15— Battery Ground Cable
16— Battery
17— Voltage Regulator 18—
Fuse

19— Instrument Cluster

A—Hi-Beam
Indicator

B—Auxiliary
C—Instrument
Lights

D—Oil
Pressure Indicator
E—Charging
Indicator
F—Temperature
Indicator

G—Fuel
Gauge
H—Instrument Voltage Regulator
20— Ignition and Starter Switch 21—
Flashei
(Directional Signal)
22—
Horn
Button 23— Directional Signal Switch
24— 4-Way Flasher Switch
25—
Flasher
(4-Way)
26—
Fuse

27—
Main
Light Switch 28—
Stop
Light Switch — Rear
29—
Fuel
Gauge
Tank
Unit
30—
Back-Up
Light Switch
31— Right
Tail
and
Stop
Lamp
32— Right Back-Up Lamp
33—
Left
Back-Up Lamp
34—
Left
Tail
and
Stop
Lamp

in
which the key can be removed. Turning the key
to the
left
energizes
auxiliary
equipment
such as
windshield wipers, radio, and heater. The turn
signal
lights
will
operate
with the
ignition
key in
either the
left
or right
position.
The
ignition
switch is held in
position
by a
tension
spring on the back
of the instrument panel and a
notched
bezel on
the front of the instrument panel.
H-8.
Lighting System

The
wiring for the lighting
system
is shown in the
wiring diagrams, Figs. H-2 thru H-7 of the manual,
which indicate the various units in relation to their

position
in the vehicle. The lighting circuit is pro­
tected
by an overload circuit breaker
mounted
on the rear of the light switch.
The
main light switch controls the lighting
system
177

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 DC
ammeter — 0 to 60 ampere

DC
ammeter — 0 to 5 ampere

DC
voltmeter — 0 to 16 volt
Rheostat — 40 ohm capable of
handling
3 amps.

Carbon
Pile — 45 amperes

b.
Diode Rectifier Tester C-3829.

c.
12-volt DC
test
lamp.

d.
Ohmmeter of any commercial type is not ab­solutely necessary but can be helpful.

H-69.
Isolation Diode
Check

With
the ignition key in the off position the correct voltage at the auxiliary terminal is zero volts. If
voltage measured at auxiliary terminal is the same as voltage at output terminal, the isolation diode
is shorted. In most cases, the charge indicator lamp
would be glowing with the ignition off if the isola­ tion diode were shorted. Refer to Fig. H-23.
GREEN

DC
VOLTS
13401

FIG.
H-23—ISOLATION DIODE
TEST-
SHORTED DIODE
With
the engine running the correct voltage at the

auxiliary
terminal is 15.4 volts and at output ter­

minal
is 14.4 volts. If voltage of auxiliary terminal
is 15.4 volts, while at output terminal it is 12 volts

or
battery voltage, the isolation diode is open. In
most cases, this would be indicated by the charge

GREEN

TO
CHARGE
INDICATOR
LAMP1

15.4
VOLTS BLACK
VOLT

REG DC
VOLTS

BATTERY

DC
VOLTS
FIG.
H-24—ISOLATION DIODE
TEST-

OPEN DIODE
indicator
lamp glowing when the engine is running.

Refer
to Fig. H-24.

If
the isolation diode is shorted or open, the heat

sink
and diode should be replaced as an assembly.

At
the time of manufacture, the diode is pressed into the heat sink and the complete assembly is in­
sulated from the alternator housing.

H-70.
Alternator Output Test

This
test
excludes the regulator from the alternator
system, thereby isolating the problem to either the regulator or alternator. Disconnect field and voltage regulator plug and
connect jumper from auxiliary terminal to field

terminal.
Start
engine and run at idle. Refer to

Fig.
H-25.
DC
VOLTS

13403

FIG.
H-25—ALTERNATOR OUTPUT
TEST
If
voltage at auxiliary terminal rises to 15 or 16
volts now, when it did not with voltage regulator
connected, then defect is in regulator and it should
be replaced. If voltage
does
not rise at auxiliary

terminal,
defect is in alternator stator or rectifier diodes, if field circuit checked out properly. For
defects
in stator or diodes, remove alternator from vehicle.

If
rated current output is obtained with at least 13
volts but less than 15 volts at the output terminal,
the alternator is functioning properly.

Caution:
Do not exceed rated current output of
alternator
by increasing load on alternator.

If
rated
current
output cannot be obtained, proceed

with
the
tests
and checks given in the following
paragraphs
and isolate the cause.
Note: The system is designed to produce slightly
more output at low operating temperatures and less
at higher temperatures to accommodate the
varying
demands of electrical power normally consumed at

these
temperatures.

H-71.
Regulator Test

The
regulator should be checked with an alternator
that is functioning properly. If the alternator is questionable, perform the Alternator Output Test
(Par
H-70) which excludes the regulator from the

charging
system and, therefore,
tests
the condition
of the alternator alone. 196

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
require
a slight rotation of the pinion to index it
into the ring gear. When the
engine
starts the drive
pinion
will
automatically demesh from the ring
gear and return to its normal position.
H-107. Starter Solenoid Switch (Prestolite)
•
Refer to
Figs.
H-44 and H-45.

Should
a starting motor
fail
to deliver maximum power the fault may be due to
voltage
drop at the
starting switch contacts due to corrosion or
burn­

ing.
Check
the switch by comparing the
voltage

at the battery terminals and that at the starting 13407

FIG.
H-44—STARTER SOLENOID—HURRICANE
F4
FIG.
H-46—PRESTOLITE STARTER
AND SOLENOID—V-6 ENGINE
switch terminals. The
voltage
drop should not
exceed .05 volts per 100 amperes.
Should
it be impossible to file the switch contact
plates to obtain a clean
full
surface contact the
switch should be replaced.
Current
model starting switches are of the
solenoid type, mounted directly on the starting
motors.
This
type switch is energized by turning
the ignition key to the extreme right position.

Should
a solenoid switch
fail
in service it is neces­

sary
to install a new solenoid assembly,
a.
To remove the solenoid switch first remove the nut and lock washer securing the solenoid strap to the starter
post.
Then
remove nut and lock washer securing battery positive cable to solenoid
post.

Tape
end of battery cable to eliminate the pos- 207

'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