JEEP CJ 1953 Service Manual

'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
Regulator
ground screw to battery ground post
—.03-volt maximum.

Generator
frame to battery ground post—.03-volt
maximum.

H-47.
Test Procedure

a.
Circuit
Breaker—Connect
an ammeter in series between the regulator B-terminal and the lead
wire
removed from that terminal. Connect a
voltmeter between the regulator
A-terminal
and the regulator mounting base. Disconnect the field lead

from
the regulator
F-terminal
and insert a variable resistance (3 amp., 50 ohm capacity) between the

lead
and the regulator terminal. Run the generator
at about 1000 generator rpm. Insert all the re­
sistance in the field
circuit,
then slowly reduce the
resistance noting the voltage reading just before the change caused by the closing of the circuit

breaker.
Increase the charging rate to the figure
specified for the regulator being tested then reduce
the charging rate by inserting resistance in the
field
circuit.
Note
the voltmeter and ammeter

reading
just before the circuit breaker
opens
and
the ammeter reading drops to zero. The closing voltage and the opening voltage or current should
be within the limits specified. An accurate method
for noting the exact instant of the opening or closing
of the circuit breaker is to connect a headphone (2000 ohms or higher) to the battery and armature

terminals
of the regulator. When the contacts
open or close a
click
will
be
heard
in the headphones.
To
adjust the closing voltage change the armature

spring
tension by bending the hanger at the lower end of the spring. Increase the spring tension to

raise
the closing voltage or decrease the tension
to lower the closing voltage. To adjust the opening voltage raise or lower the stationary contact
keeping the contacts perfectly aligned. Increasing
the contact gap lowers the opening
'
voltage.
Change
the contact gap by expanding or contract­
ing the stationary contact bracket, keeping the
contacts aligned. Do not adjust the gap between
the contacts to less than the specified minimum.

b.
Voltage Regulator—Connect the ammeter as in

step
a. Connect the voltmeter between the regulator
B-terminal
and the regulator base. Remove the

variable
resistance from the field
circuit.
Run the
generator at
half
output for 15 minutes to bring
the regulator to normal operating temperature.

Keep
the cover on the regulator during the
warm-

up period and also when taking readings.
Stop the engine then bring it up to approximately 2500 generator rpm. Adjust the amperage to
half

maximum
output by turning on lights or accessor­
ies and then
note
the voltmeter reading.
This
read­

ing should be within the limits specified for the voltage regulator operation. To adjust the oper­
ating voltage change the
armature
spring tension by
bending the hanger at the lower end of the
arma­

ture
spring. After each adjustment
stop
the engine then restart it.
Bring
it up to speed and adjust the

current
before taking a reading. In order to obtain

an
accurate indication of the operation of the volt­
age regulator unit connect a headphone (2000 ohm

or
higher) between the
F-terminal
and ground to

pick
up the sound of the opening and closing of the
contacts. The clicks should be regular and clear without irregularities or missing. If the
tone
is not

clear
and regular remove the regulator cover and
inspect the contacts. The contacts should be flat
and
not burned excessively and should be aligned
to make
full
face contact. If the contacts need
cleaning refer to paragraph d for the method.

c.
Current
Regulator—Connect the regulator and the
test
equipment as in
step
b. Running the generator at approximately 3000 generator rpm.,

turn
on lights and accessories so that the generator must charge at maximum rate. The ammeter should give a reading within the limits specified.

To
adjust opening amperage, change the armature

spring
tension by bending the hanger at the lower
end of the armature spring. After each adjustment,

stop
the engine, then restart it.
Bring
the engine up to speed and take an ammeter reading. Keep
the cover on the regulator when taking
these

readings.

Connect
a headphone (2000 ohms or higher) be­
tween the regulator
F-terminal
and ground to pick
up the sound of opening and closing of the contacts.

Clear,
regular clicks should be heard over the
headphones; they should not be
irregular
or missing.
If
the
tone
is not clear and regular remove the
regulator cover and inspect the contacts. The
contacts should be flat and not burned excessively

and
should be aligned to make
full
face contact. If
the contacts need cleaning refer to paragraph d.
below for the method.

d.
Contacts—Inspect the contacts on all three
units.
In normal use the contacts
will
become

grayed.
If the contacts are burned or dirty or if they are not smooth, file the contacts with a #6

American,
Swiss cut, equalling file. Move the file

parallel
and lengthwise to the armature.
File
just
enough so that the contacts present a smooth
sur­

face toward each other. It is not necessary to remove every trace of pitting. After filing, dampen

a
piece of linen or lintless bond tape in refined

carbon
tetrachloride and draw the tape between
the contacts. Repeat with a dry piece of tape. Use
clean
tape for each set of contacts.
e. Recheck—Operate the unit at
half
maximum
output for five minutes with the cover on the regu­

lator.
Repeat the testing procedure for all units as described in a, b, c above. Be sure cover is on regu­

lator
when taking readings.

H-48.
Quick
Checks

H-49.
Low Charging Rate with a
Fully
Charged
Battery

A
fully charged battery and a low charging rate
indicates normal regulator operation.
A
further check of the regulator operation can be
made by using the starting motor for 5 to 10
seconds with the ignition switch in the "off" posi­ tion.
Then
start the engine and operate at a genera­
tor speed of 2500 to 3000 rpm. The charging rate should rise to its maximum value then taper off to

a
minimum charge as the battery becomes charged.

H-50.
High Charging Rate with a
Fully
Charged
Battery

This
is usually an indication that the voltage regu­

lator
is not operating correctly. The high voltage 192

'Jeep1
UNIVERSAL
SERIES SERVICE
MANUAL

H
will
cause the battery to gas excessively and
will

shorten the life of the ignition contacts and, in

general,
will
have a detrimental
effect
on all con­
nected load.

Connect
an ammeter in series with the regulator
"B"
terminal and the lead removed from the termi­

nal.
Run the generator at a medium speed and per­

form
the following operation. After each
test
is
completed reconnect whatever leads have been opened.

H-51.
Test One
Disconnect the field lead at the generator.

a.
Output drops to zero—shorted field circuit in regulator or in wiring harness. See
test
2.

b.
Output
does
not drop—shorted field circuit in
generator. Inspect generator.

H-52.
Test Two
Disconnect the field lead at the regulator.

a.
Output drops to zero—shorted field in regulator.
See
test
3.

b.
Output
does
not drop—shorted wiring harness.

Repair
or replace wiring harness.

H-53.
Test
Three

Remove the regulator cover and hold the
voltage

regulator contacts open.

a.
Output drops to zero—regulator contacts stick­

ing,
regulator out of adjustment, or regulator in­ operative.
Check
operation
(test
5), check for high
resistance
(test
4), and clean contacts per instruc­
tions in Par. H-56.

b.
Output
does
not drop—shorted field circuit in
the regulator.
Clean
the regulator contacts and in­ spect the regulator visually for incorrect wiring be­
tween units and shorted leads.

H-54.
Test
Four

Operate
the units at 10 amperes output and meas­

ure
the
voltage
drop from the regulator base to
the generator frame.

a.
Voltage reading below .03 volts—ground
cir­
cuit
is satisfactory. See
test
5.

b.
Voltage reading above .03 volts—Inspect ground

circuit
for poor connections and eliminate the high
resistance. See
test
5.

H-56.
Test
Five

Connect
a headphone from the regulator field ter­
minal
to the base and hold the current regulator
contacts closed.

a.
A steady beat is heard—voltage regulator oper­
ating.
Reset regulator as in the operation
test,

Par.
H-47.

b.
An unsteady beat is heard—dirty or sticking
contacts.
Clean
contacts per instructions in Par.

H-56.
c.
No beat is heard—inoperative
voltage
regulator
unit.
Adjust regulator operation as in the operation

test.
If the regulator cannot be adjusted within
limits,
remove for overhaul.
H-56.
Cleaning of Contacts

Clean
the
voltage
regulator contacts with a #6

American
Swiss cut equalling file.
File
lengthwise

and
parallel to the armature and then clean the
contacts with clean linen tape.
First
draw a piece
of tape that has been wet with carbon tetrachlor­
ide
between
the contacts then follow with dry tape. Reset the regulator operation as in the oper­
ation
test,
Par. H-47.

H-57.
Low Battery and a Low or No Charging Rate

Check
all wiring for
loose
connections, frayed in­
sulation and high resistance connections and cor­
rect
any fault.

Make
sure the generator operates correctly with­
out the regulator in the
circuit.
Remove the "A"

and
"B" leads from the regulator and connect an
ammeter
between
them. Remove the field lead from
the regulator and while operating at idle speed
touch the field lead to the regulator base. Increase
the speed slowly noting the charging rate. 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.

Connect
an ammeter
between
the battery lead and
the regulator
"B"
terminal. Connect the field lead to the regulator "F" terminal and connect the

armature
lead to the regulator
"A"
terminal.
Con­

nect a voltmeter from the regulator
"A"
terminal to
the regulator base. Operate the generator at a medium speed and perform the following
tests:

H-58.
Test Six

Read
the voltmeter.

a.
Voltage builds up—open series
circuit.
See
test
7.
b.
Voltage
does
not build up—regulator out of ad­
justment, field circuit open, grounded series
circuit.
See
test
8.

H-59.
Test Seven
Remove the regulator cover and with the generator
operating at a medium speed hold the circuit

breaker
contacts closed.

a.
Ammeter shows no charge—open
circuit
breaker
shunt winding, incorrect setting of circuit breaker,

or
dirty contacts.
Clean
contacts and reset circuit

breaker
as in
Par.
H-47d. If the circuit breaker
can­
not be set, the shunt coil is open and the regulator
should be removed for overhaul.

b.
No generator output—clean the circuit breaker
contacts and try the
test
again. If there is
still
no
charge the series windings are open and the regu­

lator
should be removed for overhaul.

H-60.
Test
Eight

Run
the generator at idle speed and momentarily
connect a jumper from the
F-terminal
to the regu­

lator
base.

a.
Voltage builds up—open field circuit or regula­
tor out of adjustment. See
test
9.
b.
Voltage
does
not build up—grounded series
cir­

cuit.
Remove regulator for overhaul. 193

H

ELECTRICAL
SYSTEM H-61.
Test Nine

Operate
at a medium speed with the jumper re­ moved. Remove the regulator cover and hold the

voltage
regulator contacts closed.

a.
Voltage builds up—voltage regulator contacts
burned
or dirty or incorrect regulator setting.

Clean
the contacts and adjust the regulator as in

Par.
H-47d.

b.
Voltage
does
not build up—clean contacts and
repeat
test.
If the
voltage
still
does
not build up, see
test
10.

H-62.
Test Ten
Remove the regulator cover and hold the current
regulator contacts closed.

a.
Voltage builds up—current regulator contacts
burned
or dirty or incorrect regulator setting.

Clean
the contacts and adjust the regulator as in

Par.
H-47d.

b.
Voltage
does
not build up—clean the contacts

and
repeat the
test.
If the
voltage
still
does
not

build
up remove the regulator for an overhaul.

H-63. ALTERNATOR CHARGING SYSTEM

Most vehicles have, as standard equipment, a 35-

amp.,
12-volt, negative ground alternator and a
transistorized
voltage
regulator.
The
alternator charging circuit consists of the
battery, alternator,
voltage
regulator, ignition
switch,
and charge indicator light.

An
alternator differs from a conventional DC
shunt generator in that the armature is stationary,

and
is called the stator, while the field rotates,
and
is called the rotor.
With
the alternator con­
struction,
the higher current values involved in
the stator may be conducted to the external circuit through fixed leads and connections, rather than
through a rotating commutator and brushes, as in the DC generator.

The
alternator employs a three-phase stator
winding. The rotor consists of a field coil encased
between
six poled interleaved sections, producing

a
twelve
pole
magnetic field with alternator north

and
south poles. By rotating the rotor inside the stator, an alternating current is induced in the stator windings.
This
alternating current is
changed to direct current by
diodes
and conducted
to the output terminal of the alternator.
Six
silicon
diode
rectifiers act as electrical one-way valves.
Three
of the
diodes
have negative polarity

and
are grounded. The other three
diodes
have
positive polarity and connected to the output
terminal.
In all alternators discussed in this

manual,
the
diodes
are pressed into heat sinks.

There
are two heat sinks, one positive and the
other negative.

Since
the
diodes
have a high resistance to the
flow of
current
in one direction and a low resistance
in
the
opposite
direction, they are connected in a
manner
which allows current to flow from the
alternator to the battery in the low resistance
direction.
The high resistance in the
opposite

direction prevents the flow of current from the
battery to the alternator. Because of this feature,
no
circuit
breaker
is
required
between
the alternator
and
the battery.
Residual
magnetism in the rotor field
poles
is
negligible. Therefore the starting field current must be supplied by the battery. It is connected
to the field winding through the ignition switch

and
charge indicator lamp.
As
in the DC shunt generator, the alternator
voltage
is regulated by varying the field current.
In
these
alternator systems, this is accomplished
electronically in the transistorized
voltage
reg­
ulator.
No current regulator is required since all
alternators have self-limiting current character­
istics.

The
entire DC output of the alternator has to pass
through the isolation diode. The isolation
diode
is
not essential for rectification. Its purpose is threefold.
It
provides automatic solid
state
switch for
illumi­

nating the alternator charge
-
discharge indicator
light when the alternator is not charging properly.
It
automatically connects the
voltage
regulator to
the alternator and battery when the alternator is
operating.
It
eliminates electrical leakage across the alternator

diodes
so that leakage is negligible when the vehicle
is not in use.
The
isolation
diode
is mounted in a separate alumi­

num
heat sink. The 35-amp. alternator has a single
silicon diode. The alternator is designed to supply the electrical demands of the battery and the
accessory circuits through a wide range of
engine

speeds. The alternator is lighter and more compact

than
a conventional DC shunt generator of com­

parable
electrical size.

The
principal
components of the alternator are
the stator, the rotor, the slip ring end head, the

drive
end head, the
diode
rectifiers, and the isolation diode.

a.
The stator consists of a laminated iron core on

which
the three-phase windings are wound in
slots
around
the inside circumference. A
pair
of leads
are
connected to each of the three points of the
winding. One of each
pair
of leads connects to a
negative
diode
rectifier and one to a positive
diode
rectifier.

b.
The rotor consists of a single field coil encased

between
two six-fingered, interleaved iron sections assembled to the shaft. The two ends of the field
coil
are connected to two slip rings which are in­
sulated from each other and from the shaft.
c. The slip ring end head supports the rectifier heat sinks; a prelubricated sealed
ball
bearing, in

which
the rotor shaft rotates; and the brush holders
and
brushes.

d.
The drive end head supports a prelubricated
sealed
ball
bearing in which the drive end of the rotor shaft rotates.
e. The
diode
rectifiers are pressed in the rectifier brackets or heat sinks and are connected to the
stator leads.
f. The isolation
diode
is pressed in the aluminum heat sink mounted to the
rear
of the alternator. The
complete assembly is covered with a red insulating coating.

For
repairing the alternator, many of its major components are furnished as complete assemblies

including:
complete brush assembly which requires 194

'Jeep*
UNIVERSAL
SERIES SERVICE
MANUAL

H
no soldering or unsoldering of leads; two complete

rectifying
diode assemblies
which
eliminate the need
for removing and replacing individual diodes; a
corpplete 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
output current is determined by the battery electri­
cal
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-64. ALTERNATOR
PRECAUTIONS

The
following precautions must be observed to
prevent damage to the alternator and regulator.

a.
Never reverse battery connections. Always

check
the battery polarity with a voltmeter before

any
connections are made to be sure that all con­
nections correspond to the battery ground polarity of the vehicle.

b.
Booster batteries for starting must be properly
connected. Make sure that the negative cable of
the booster battery is connected to the negative

terminal
of the battery in the vehicle. The positive
cable of the booster battery should be connected
to the positive terminal of the battery in the
vehicle.

c.
Disconnect the battery cables before using a fast charger.

d.
Never use a fast charger as a booster for

starting
the vehicle.

e.
Never disconnect the
voltage
regulator while
the
engine
is running.

f.
Do not ground the alternator output terminal.
g.
Do not operate the alternator on an open
circuit
with
the field energized.

h.
Do not attempt to polarize an alternator.

These
precautions are stated here as an aid to

service
personnel. They are also restated at appro­

priate
places in the
text
of this section of the
manual.

H-65. ALTERNATOR
CHARGING
SYSTEM SERVICE
Important:
All alternator
tests
for the 35, 40 and
55 amp alternator are the same, however, there is a
difference
between
the location of the various ter­

minals
and field current specifications. The field

current
of the 35 amp alternator should be 1.7 to 2.3 amps, 40 and 55 amp alternators should be 1.8
to 2.4 amps, with
full
battery
voltage
applied to
the filed coil. Disassembly and assembly procedures

are
the same for all three alternators.
Terminal
locations and wire harness color
codes
for the 35,
40 and 55 amp alternator are shown in Fig. H-38.

H-66.
Service Diagnosis

In
diagnosing a suspected malfunction of the

alternator
charging system, consideration must
be given to the complete electrical power plant of the vehicle; including the alternator, regulator,
ignition switch, charge indicator lamp, battery,

and
all associated wiring. If it is suspected that the

alternator
is not fully charging the battery and

fulfilling
the electrical requirements of the electrical
system, several checks should be made before

checking
the alternator itself:

Note:
Whenever service is required in connection

with
an alternator problem, the first
step
should be to verify that the wiring harness hook-up is correct
as indicated in Fig. H-38.

a.
Test the condition of the battery and
state
of
charge
(Par. H-2).
If the battery is not fully charged
and
in
good
condition, use a replacement battery
for making alternator system
tests.

Caution:
Make certain that the negative battery

post
is connected to ground when making the
battery installation. Serious damage to the alter­

nator
can result if battery polarity is reversed.

b.
Check
fan belt for proper tension (Par.
C-27).

Caution:
To increase belt tension, apply pressure
to alternator front housing only as permanent damage can result if pressure is applied to
rear

housing.

H-67.
Alternator In Vehicle Tests

The
following
tests
are made with the alternator

in
the vehicle with output and regulator connec­
tions maintained to the alternator except as noted

in
Fig. H-27 and H-28. The field plug and
voltage
regulator are disconnected for
these
tests.
The

tests
are given in proper order and detail in the
following paragraphs.

a.
Isolation Diode Test: To determine if the isola­
tion diode is open or shorted, refer to Par. H-69.

b.
Alternator Output Test: To isolate the trouble
to the alternator or regulator, refer to Par. H-70.

c.
Alternator
Field
Circuit
Test: To determine the condition of the field
circuit
(brushes and rotor),

refer
to Par. H-73.

d.
Brush
Insulation
and Continuity
Test:
To deter­
mine the condition of the
brush,
refer to
Par.
H-75.

e.
Rotor In-Vehicle Test: To determine whether
the rotor coil is open or shorted, refer to
Par.
H-73.
f. Any further
tests
must be conducted with the

alternator
removed and disassembled. When this
is done, the condition of the rotor, the rectifying

and
isolation diodes, and the stator can be further
tested.

A
commercial alternator tester Sun
Electric
Model

VAT-20
or equivalent can be used to make all
necessary
tests
on the alternator system. If a com­

mercial
tester is used, follow the recommended
testing procedure outlined by the tester manu­

facturer.
If
a commercial tester is not available, follow the
testing procedure as outlined in this manual.

H-68.
Test Equipment

a.
Volt Ampere Tester such as Sun
Electric
Model

VAT-20
or equivalent with meter ranges as shown

in
the following list can be used. 195

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

'Jeep'
UNIVERSAL SERIES SERVICE
MANUAL

H
H-72.
Removal
and
Installation
of

Voltage Regulator

The
transistorized
voltage
regulator is a sealed unit.
It
cannot be disassembled or adjusted. If found to
be defective in any way, it must be replaced as
a
unit.

The
transistorized
voltage
regulator is mounted on
the fender dust shield by three mounting screws.

Wiring
connections to the charging circuit are made through a three-prong connector.

To
remove the regulator, disconnect the three
-
prong connector and remove the three mounting

screws.
Installation of the regulator is the reverse
of the removal. (Refer to Fig. H-26.)
FIG.
H-26—VOLTAGE
REGULATOR

H-73.
Alternator Field Circuit Test

Voltage
Test — Refer to Fig. H-27.

a.
With the ignition key on and
engine
not
run­
ning,
the correct
voltage
at the auxiliary terminal is
approximately 1.5 volts. If the
voltage
at auxiliary

terminal
is higher than 2 volts, field circuit is defective — check brushes.
GREEN

13404

FIG.
H-27—FIELD
CIRCUIT TEST—VOLTAGE If
voltage
reads zero volts at auxiliary terminal,
check charge indicator lamp and associated circuit.
If
this
voltage
is not correct, continue with the fol­
lowing
test
described in paragraph b.
Amperage Test — Refer to Fig. H-28. b.
This
test
evaluates complete field circuit, inde­
pendent of
voltage
regulator.
Circuit
is through
brushes, slip rings, rotor to ground. With ignition switch off, current should be 2 to 2.5 amps. If
less

than
this, check brushes and slip rings. It is de­

sirable
to use a field rheostat in series with meter
for protection of the meter. If field is shorted, ex­
cessive current
will
flow through meter and dam­
age may result.
GREEN
FIELD
WIRE

DISCONNECTED

13405

FIG.
H-28—FIELD
CIRCUIT TEST- AMPERAGE
DRAW
H-74.
Brush Removal
and
Inspection

Refer
to Fig. H-29.

The
brushes can be removed and inspected while
the alternator is in the vehicle.

a.
Disconnect the plug to the field terminal. b. Remove the two screws and brush cover.
c. Remove brushes.
d.
Inspect brushes for excessive wear and proper
tension. The brushes can be installed by reversing
the above procedure.

H-75.
Brush Insulation
and
Continuity Test

Refer
to Fig. H-30.

a.
Connect leads of a 12-volt
test
lamp to field
FIG.
H-29—BRUSH
REMOVAL

1—
Screw

2—
Cover

3—
Brush
and
Holder
Assembly
4—
Alternator
197

H

ELECTRICAL
SYSTEM
terminal
and bracket. Test lamp should not light.

If
it
does,
the
brush
is shorted and must be replaced,
b.
Connect one lead of an ohmmeter to field ter­

minal
and the other lead to insulated brush. Re­
sistance reading should be zero. Move brush and

brush
lead wire to make certain that the brush lead wire connections are not intermittent. Resist­
ance reading should not vary when brush and lead

wire
are being moved.

C.
Connect ohmmeter leads to bracket and grounded brush. Resistance reading should be zero.
Repeat same
test
on brush lead wire as described

in
step
b above.
FIG.
H-30—INSULATION
AND
CONTINUITY

TEST
POINTS
1^-Brackct

2—
Field
Terminal

3—
Grounded
Brush

4—
Insulated
Brush

H-76.
Rotor
In-Vehicle
Tests

a.
Reference Par. H-73, Fig. H-28.
b.
To check for a short circuit in the rotor wind­
ings, the alternator should be removed. Refer to

Par.
H-79 for rotor bench
tests.

H-77.
ALTERNATOR
BENCH
TESTS

When
the various
tests
given in
Par.
H-69 through
H-76 have determined a fault within the alternator itself, the alternator should be removed from the vehicle and the following
tests
given in
sequence

to isolate the trouble to a particular
component

of the alternator.
Note
that certain
tests
can be
performed after the alternator is removed and
before
it is disassembled.

H-78.
ALTERNATOR
REMOVAL
Note:
Brushes and isolation
diode
can be removed

from
alternator without removing unit from vehicle.

a.
Disconnect all lead connections at alternator.
b.
Remove nut and
bolt
at alternator support

bracket.
Remove nut, bolt, washer, and adjustment

bracket.
Remove belt from alternator pulley. The alternator is now free to be removed from the
vehicle.

H-79.
Rotor Tests
—
Bench

This
test
checks the condition of the rotor (field coil) for
open
or shorted field winding, excessively

worn
or sticky brushes, and
open
connections. It should be performed with the brush assembly in­
stalled in the alternator.

a.
The field coil is checked for a short circuit
by connecting a fully charged battery and an ammeter in series with the two slip rings.

A
rheostat is placed in series in the
circuit
to protect
the instruments and
components
of the alternator. Set rheostat to maximum resistance (40 ohms)

before
making connections.

b.
Slowly reduce resistance of rheostat to zero.

Then
take reading on ammeter. With full battery
voltage
applied to the field coil, the field current
of the 35-amp. alternator should be 1.7 to 2.3 amp.

Note:
The field current of the 40 and 55 amp.
alternator should be 1.8 to 2.4 amps with full battery
voltage
applied to the field coil.
c.
Turn
rotor by hand, noting reading. Rotating
rotor
will
indicate if brushes are making
good
elec­

trical
contact. A slight fluctuation of reading (0.2

amp.)
is to be expected.
If
field current is not within limits, inspect brushes

and
slip rings for
excessive
dirt, sticky, or broken
brushes, and bad connections.
Check
brush as­ sembly for short and continuity (Par. H-75). Make
same
test
to slip rings. Reinstall repaired or known
good
brush assembly and repeat
test.
If
the field current is
above
the maximum value
specified, it indicates that the field coil is either
shorted to rotor or field coil has shorted windings.
If
the field current is zero, it indicates that the field

coil
or coil-to-slip ring connection is open. If the field
current
is considerably
less
than the value
specified, it indicates a poor coil-to-slip ring con­ nection or poor brush-to-slip ring connection.

d.
To check continuity of the rotor, disconnect the
battery and connect an ohmmeter directly across
the field. Resistance
between
field terminal and ground terminal should be approximately 6 ohms.
If
resistance is high, field coil is shorted.

e.
If rotor is found to be
defective
in
above
tests,
repeat the
above
tests
when the rotor is removed

from
the alternator by connecting the
test
circuit
to rotor slip rings to ascertain findings.
Field
current

will
be approximately 0.2 amp. higher than the
maximum
value because of the normal brush-to-

slip-ring
contact resistance that reduces field
current
slightly. If the rotor is found to be de­
fective, it should be replaced.

H-80.
Alternator Disassembly

Refer
to Fig. H-31.

a.
Remove brush assembly by removing two tap­ ping screws and cover. Then pull the brush as- 198

'Jeep'
UNIVERSAL
SERIES SERVICE
MANUAL

H

©
© © ® (a
1—
Bolt

2— Cap
Screw

3—
Brush
Assembly
Cover

4—
Brush
Assembly
5—
Locknut

6—
Isolation
Diode 7— Nut
8—
Insulated
Washer
9—
Rear
Housing

10—Slip
Ring
FIG.
H-31—ALTERNATOR

11—
Insulated
Washer 12— Negative Diode Assembly
13—
Positive Diode Assembly
14—
Stator

15—
Rear
Bearing 16—
Rotor
17—
Retaining
Clip

18—
Front
Bearing
19—
Front
Housing
20— Nut 11485
21—
Fan
22—
Pulley

23—
Lock
Washer
24— Nut 25—
Woodruff
Key 26—
Bushing

27—
Insulated
Sleeve
28— Nut sembly straight out until the brushes are clear of

rotor
assembly.
Lift
the brush assembly out of the housing.

b.
Remove the isolation
diode
assembly by re­
moving nuts.

c.
Remove fan, pulley, lock
washer,
nut and spacer.
With
the nut removed, remove pulley using
Puller,

the other parts can then be removed easily from the

rotor
shaft. The spacer
will
not
come
off until the key is removed.

d.
Separate front housing from
rear
housing by
removing
bolts
and nuts.
Then
insert blade of
a
small screwdriver in the stator
slots
between
the
stator and the front housing. Wedge apart the
halves of the alternator.

Caution:
Take
care not to insert the screwdriver
blade deeper than J/f6" [0,16 cm.] below a stator.

Otherwise
damage to the stator windings may

result.
It may be necessary to apply pressure at

several
points around the stator to extract rotor

and
front housing as an assembly. Be careful not
to
burr
the stator core as this would make reas­ sembly difficult.

e.
Remove the two rectifying
diode
heat sink as­semblies and the stator as a complete unit from
the
rear
housing by removing nuts and locknuts.
Note
that the positive
diode
assembly is insulated

from
the alternator housing by insulated washers

and
insulated sleeves.
f. The
diode
and stator assemblies may now be
tested
as outlined in
Par.
H-83.
For
additional
test­
ing
(Pars.
H-84 and H-85) or to replace a
diode
heat
sink
assembly, unsolder the three soldered con­
nections at the
diodes
to separate heat sink from stator.

Caution:
When unsoldering the stator wires from
the rectifier
diode
assembly, provide a heat sink
to the
diode
terminal using a
pair
of long-nosed
pliers
to dissipate the heat away from the diodes.

g.
To remove the rotor assembly from the front
housing remove the woodruff key and split spring

washer
(bearing retainer).
FIG.
H-32—REMOVING
FRONT
BEARING

1—Front
Bearing Remover C-4068
h.
With
the woodruff key removed and the split

spring
washer
loose,
the rotor may be removed
from
the front housing by tapping the rotor shaft
on a
soft
wood surface.

i.
Remove the front and
rear
bearings from the

rotor
shaft by using Bearing Remover C-4068 for
the front bearing, as shown in
Fig.
H-32, and
Bear­
ing Remover C-3936 for the
rear
bearing, as shown

in Fig.
H-33.

H-81.
General
Inspection

a.
All parts should be wiped clean and visually inspected for wear, distortion, and signs of over­
heating or mechanical interference.

b.
Check
the bearings for roughness or excessive

clearance.
They should be replaced if found defective.

Note:
New bearings are prelubricated. Additional

lubrication
is not required. 199

H
ELECTRICAL
SYSTEM
|
lists
>

FIG.
H-33—REMOVING
REAR
BEARING

1—
Rear
Bearing

2—
Rear
Bearing
Remover C-3936
The
alternator end housing may be
wiped
clean

with
a
cloth
dampened in solvent if excessively
dirty
but should not be
buffed
as this
will
destroy
special treatment given to
inhibit
corrosion.

H-82.
Out-Of-Circuit
Rotor Test

Refer
to
Pars.
H-76 and H-79 for
tests
to be per­ formed on the rotor. If
these
tests
were not per­formed while the alternator was assembled, they

can
be performed with the alternator removed by following the procedure given in
these
paragraphs.

H-83.
Out-Of-Circuit
Stator Leakage Test Disassemble alternator and remove the rectifier
diode plates and stator as shown in Fig. H-34 as
an
assembly.
An
ohmmeter or 12-volt
test
lamp may be used,

a.
Connect one ohmmeter or
test
lamp probe to
one of the rectifier diode terminals and the other
to the stator as shown in Fig. H-34.
FIG.
H-34—STATOR
LEAKAGE
TEST
POINTS
1—
Stator

2—
Diode
Terminal
Resistance
reading should be infinite or
test
lamp
should not light. If resistance reading is not infinite

or
test
lamp lights, high leakage or a short exists between stator winding and stator. In either case,
the diode heat sinks should be separated from the
stator (Par. H-80) to ascertain whether the stator
should be replaced (Par. H-84).

H-84.
Stator
Coil
Leakage and
Continuity
Test

This
test
checks for shorts or leakage between
stator coil windings. To conduct the
test,
the wind­
ing junctions must be separated as shown in Fig.

H-35.
An ohmmeter or 12-volt
test
lamp may be used.
|
.11521 •

FIG.
H-35—STATOR
LEAKAGE
AND
CONTINUITY
TEST
POINTS 1—
Test
Point 3—Test Point 5—Test Point

2—
Test
Point 4—Test Point 6—Test Point

a.
Connect one of the ohmmeter or
test
lamp probes to
test
point 4 as shown in Fig. H-35.
Con­

nect the other
test
probe to
test
point 5 and then to

test
point 6. Resistance should be infinite or
test

lamp
should not light.

b.
Connect one
test
probe to point 1 and the other
to point 3 and then point 2. Resistance should be infinite or
test
lamp should not light.

In
either
test,
if the resistance reading is not infinite

or
the
test
lamp lights, high leakage or a short
exists between stator windings. Stator should be
replaced.

c.
Measure resistance of each winding in stator between
test
points 4 and 1, 5 and 3, and 6 and 2,
in Fig.
H-35. 200