1993 DODGE TRUCK Service Repair Manual

•

ELECTRICAL
ELECTRICAL
8A - 1

Group

AUDIO
SYSTEMS
8F
BATTERY/STARTER/GENERATOR
SERVICE
.. 8B
BATTERY/STARTING/CHARGING
SYSTEMS

DIAGNOSTICS
8A

HORNS
8G

IGNITION
SYSTEMS
8D
INSTRUMENT PANEL AND
GAUGES
8E

LAMPS
8L

POWER
LOCKS
8P
INDEX

Group

POWER
MIRRORS
8T

POWER
WINDOWS 8S

REAR
WINDOW DEFOGGER 8N
TURN
SIGNALS
AND HAZARD WARNING
FLASHERS
8J
VEHICLE
SPEED
CONTROL SYSTEM 8H WARNING BUZZER SYSTEM 8U
WINDSHIELD WIPERS AND
WASHERS
8K
WIRING DIAGRAMS 8W

BATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICS
CONTENTS
page
page
BATTERY TEST
PROCEDURES
2 GENERATOR TEST
PROCEDURES
ON VEHICLE . 13

ENGINE
STARTER MOTOR TEST
PROCEDURES
..9 SPECIFICATIONS 18

GENERAL
INFORMATION 1

GENERAL INFORMATION

The Battery, Starting, and Charging Systems oper­
ate with one another, and therefore, must be thor­
oughly tested as a complete system. In order for the
vehicle to start and charge properly, it must have a
battery that will perform to specifications. The starter
motor, generator, wiring, and electronics also must
perform within specifications. Group 8A covers Start­ ing (Fig. 1) and Charging (Fig. 2) System diagnostic
procedures. These procedures include the most basic
conventional methods to On-Board Diagnostics (OBD)
built into the Powertrain Control Module (PCM).
Use of an ammeter, volt/ohmmeter, battery
charger, carbon pile rheostat (load tester), and 12
volt test light will be required.
All OBD sensing systems are monitored by the
PCM. The PCM will store in memory any detectable
failure in the monitored circuits. Refer to Using On-
Board Diagnostic System in this group for more in­ formation.
NEGATIVE

BATTERY
CABLE

A
7

POSITIVE

BATTERY
CABLE
BATTERY

J918A-11

Fig.
1 Starting
System
Components—Typical

8A
- 2
ELECTRICAL

•

MALFUNCTION
INDICATOR
LAMP

DIAGNOSTIC SCAN
TOOL

POWERTRAIN CONTROL
MODULE
GENERATOR
BATTERY

J938A-23

Fig.
2
Charging
System
Components—Typical
BATTERY TEST
PROCEDURES

INDEX

page

Battery
Charging
6

Battery
Load Test
5

Battery
Open
Circuit
Voltage Test
.............
4

Causes
of
Battery
Discharging
3

GENERAL
INFORMATION
The battery stores, stabilizes,
and
produces electri­
cal current.
A
battery must
be
able
to
accept
a

charge
and
produce high-amperage current over
an

extended period.
A
chemical reaction takes place
be­

tween sulfuric acid solution (electrolyte)
and
lead + /-
plates
in
each cell
of the
battery.
As the
battery discharges,
the
plates collect acid from
the
electro­

lyte.
When
the
charging system charges
the
battery,
water
is
converted
to
sulfuric acid
in the
battery.
The
amount
of
acid (specific gravity)
in the
electrolyte
can
be
measured with
a
hydrometer.
A
factory
in­
stalled battery
has a
built-in test indicator
to
help
determine state-of-charge.
The
factory installed bat­
tery
is
also nonrefillable, water
can not be
added.
The battery
is
vented
to
release gases that
are cre-
page

General
Information
2
Ignition
Off
Draw (IOD)
4

State
of
Charge Test Using Test
Indicator
.......
3

Test
Indicator
3

ated when
the
battery
is
being charged.
The
battery

top,
posts,
and
terminals should
be
cleaned when other underhood maintenance
is
performed (Fig.
3).

WARNING:
DO
NOT
ATTEMPT
TO
ASSIST BOOST, CHARGE,
OR
TEST BATTERY WHEN ELECTRO­LYTE LEVEL IS BELOW THE TOP
OF
THE PLATES
(YELLOW
OR
BRIGHT COLOR
IS
VISIBLE). PER­
SONAL
INJURY
MAY
OCCUR.

When
the
electrolyte level
is
below
the top of the

plates (yellow
or
bright indicator),
the
battery must
be replaced.
The
battery must
be
completely charged (green indicator)
and the top,
posts,
and
terminals
should
be
properly cleaned before diagnostic proce­
dures
are
performed. Refer
to
Group
8B -
Battery/ Starter Service,
for
additional information.

•

ELECTRICAL
8A - 3

Fig.
3
Battery
Construction
and
Test Indicator

TEST INDICATOR
A test indicator (hydrometer) built into
the top of

the battery case, provides visual information
for
bat­
tery testing (Fig.
4). The
test indicator
is to be
used with diagnostic procedures described
in
this group.
It
is important when using
the
test indicator that
the

battery
is
relatively level
and has a
clean
top to see
correct indications.
A
light
may be
required
to
view
indicator.

WARNING:
DO
NOT USE
OPEN FLAME. EXPLOSIVE
GASES
FORM ABOVE BATTERY.
Fig.
4
Built in Test Indicator

STATE
OF
CHARGE TEST USING TEST INDICATOR
The built-in test indicator (hydrometer) measures
the specific gravity
of
the electrolyte. Specific gravity (SG)
of the
electrolyte will indicate state-of-charge
(voltage); although,
the
test indicator will
not
indi­
cate cranking capacity
of the
battery. Refer
to
Bat­
tery Load Test
for
more information. Look into
the
sight glass
and
note
the
color
of the
indicator
(Fig.

5),
refer
to the
following description
as
color indi­

cates:
GREEN-75
to
100% state-of-charge
The battery
is
adequately charged
for
more testing
or return
to use. If the
vehicle will
not
crank
for a

maximum
15
seconds, refer
to
Battery Load Test
for

more information. BLACK
OR
DARK—0
to
75% state-of-charge The battery
is
inadequately charged
and
must
be

charged until green
dot is
visible
(12.4
volts
or

greater) before
the
battery
is
tested
or
returned
to

use.
Refer
to
Causes
of
Battery Discharging
for
more information.
YELLOW
OR
BRIGHT COLOR

WARNING:
DO NOT
ATTEMPT
TO
CHARGE, TEST,
OR
ASSIST
BOOST BATTERY WHEN YELLOW
OR

BRIGHT COLOR
IS
VISIBLE. PERSONAL INJURY
MAY OCCUR.

A yellow
or
bright color indicates water (electro­
lyte) level
in
battery
is
below
the
test indicator
(Fig.
5).
Water
can not be
added
to a
maintenance free
battery.
The
battery must
be
replaced.
A low
electro­ lyte level
may be
caused
by an
over charging condi­
tion. Refer
to
Generator Test Procedures
On
Vehicle in this group.

TEST INDICATOR/STATE
OF
CHARGE

IfVW,
"TCfV

REPLACE BATTERY

lUUTu
/Otu L
f
REPLACE BATTERY

SBl
ill,
iMMiMMMMSMM^MM

GREEN BLACK

YELLOW
898A-3
Fig.
5
Test Indicator
Sight Glass

CAUSES
OF
BATTERY DISCHARGING
It
is
normal
to
have
a
small
(5 to 20
milliamperes)
draw from
the
battery with
the
ignition
in the OFF

position,
and ALL
lamps OFF.
The
constant draw
is
due
to
various electronic features
or
accessories that
require electrical current with
the
ignition
OFF to

function properly.
If a
vehicle
is not
used
for a
period of
20
days
or
more,
the
black battery disconnect
should
be
disconnected.
The
disconnect
is
located
be­

hind
the
battery
on the
engine wiring harness. This will prevent battery discharging.

ABNORMAL
BATTERY
DISCHARGING
(1) Corroded battery posts
and
terminals.
(2) Loose
or
worn generator drive belt.
(3) Electrical loads that exceed
the
output
of the

charging system
due to
equipment
or
accessories
in­
stalled after delivery. (4) Slow driving speeds (heavy traffic conditions)
or prolonged idling with high-amperage electrical systems
in use.

(5) Defective electrical circuit
or
component caus­
ing excess Ignition
Off
Draw (IOD).
(6) Defective charging system.
(7) Defective battery.

8A
- 4
ELECTRICAL

•
IGNITION
OFF
DRAW
(IOD)
Ignition off draw refers to power being drained
from the battery with the ignition turned off. A nor­
mal vehicle electrical system will draw from 5 to 20
milliamps. A vehicle that has not been operated for
an extended period of time (approximately 20 days)
may discharge the battery to an inadequate level.
Battery drain should not exceed approximately 20
MA (20 milliamps = 0.020 amps). The 20 MA are needed to supply PCM memory,
digital clock memory, and ETR (electronically tuned
radio) memory. Excessive battery drain is caused by items left
turned on, internally shorted generator, or intermit­
tent short in wiring.
If the IOD is excessive (over 20 milliamperes), the
defect must be found and corrected before replacing a
battery. In most cases the battery can be charged and returned to service.
TEST PROCEDURE Testing for higher amperage IOD must be per­
formed first to prevent damage to most milliamp
meters.
Verify that all electrical accessories are OFF. Turn
off all lights, remove ignition key, and close all

doors.
If the vehicle is equipped with electronic acces­
sories (illuminated entry, high line radio), allow the
systems to automatically shut off (time out), up to 3
minutes.
(1) After determining that the underhood lamp is
operating properly then disconnect bulb. (2) Disconnect negative cable from battery.
(3) Connect a typical 12 volt test light (low watt­
age bulb) between the negative cable clamp and the
battery negative terminal. The test light may light brightly for up to 3 min­
utes or may not light at all (depending on the elec­
trical equipment). The term brightly being used
throughout the following tests, implies the bright­ ness of the test light will be the same as if it were
connected across the battery.
The test light must be securely clamped to the neg­
ative cable and battery terminal. If the test light be­
comes disconnected during any of the IOD test, the electronic timer function will be activated and all
tests must be repeated.
(4) After 3 minutes, the test light should turn OFF
or be DIMLY lit (depending on the electrical equip­

ment).
If the test light remains brightly lit do not
disconnect it. Remove each fuse or circuit breaker (refer to Group 8 - Wiring Diagrams) until test light
is either OFF or DIMLY lit. This will eliminate the
higher amperage draw.
If test light is still bright after disconnecting each
fuse and circuit breaker, disconnect the wiring har­ ness from the generator. Refer to Generator Testing
in this group. Do not disconnect the test light. After higher amperage IOD has been corrected, low
amperage IOD may be checked.
It is now safe to install milliamp meter to check for
low amperage IOD.
(5) With test light still connected, securely clamp
an ammeter between battery negative terminal and
negative battery cable.
If the test light or the milliamp meter circuit is
broken the various timer circuits will start. Do
not open any doors or turn on any electrical ac­ cessories with the test light disconnected or the
meter may be damaged.
(6) Disconnect test light. The current draw should
not exceed 0.020 amp. If it exceeds 20 milliamps iso­
late each circuit by removing circuit breakers and

fuses.
The meter reading drops once the high current
problem is found. Repair this section of the circuit,
whether it is a wiring short or component failure.

BATTERY
OPEN CIRCUIT VOLTAGE TEST
A battery voltage (no load) test will indicate the
state of charge of a battery that will pass the Battery
Load Test described in this section. Before proceed­
ing with this test or the Battery Load Test the
battery must be completely charged as de­ scribed in Battery Charging in this section. If a battery has a no load voltage reading of 12.4
volts or greater but will not endure a load test, it is
defective and should be replaced. Refer to Group 8B,
Battery/Starter Service for instructions. To test bat­
tery no load voltage, perform the following operation: (1) Before measuring open circuit voltage, the sur­
face charge must be removed from plates. Turn head lights on for 15 seconds then allow up to 5 minutes
for voltage to stabilize. (2) Remove both battery cables, negative first.
(3) Using a voltmeter connected to the battery

posts,
see instructions provided with voltmeter, mea­ sure open circuit voltage (Fig. 6). This voltage reading will indicate state of charge,
but will not reveal cranking capacity. Refer to Bat­
tery Open Circuit Voltage chart.
BATTERY OPEN CIRCUIT VOLTAGE
Open
Circuit
Volts

Percent
Chang©

11.7
volts
or
less
0%
12.0 25%
12.2 50%
12.4 75%

12.6
or more 100%
918A-3

•

ELECTRICAL
8A - i
898A-7

Fig.
6
Testing
Open
Circuit Voltage

BATTERY LOAD
TEST
WARNING:
IF
BATTERY SHOWS SIGNS
OF
FREEZ­
ING, LEAKING, LOOSE POSTS,
OR
EXCESSIVELY
LOW ELECTROLYTE LEVEL,
DO
NOT
TEST. ACID BURNS
OR
EXPLOSIVE
CONDITION
MAY
RESULT.

A battery load test will verify
the
actual cranking
performance based
on the
cold crank rating
of the

battery.
Before performing
the
battery load test,
the

battery must
be
FULLY CHARGED.
(1) Remove both battery cables, negative first. Bat­
tery
top and
posts should
be
clean.
If
green color
is
not visible
in
indicator, charge
the
battery,
see
Bat­
tery Charging Procedures
in
this section.
(2) Connect
a
suitable Volt-Ammeter-Load tester
(Fig.
7) to the
battery posts
(Fig. 8).
Refer
to
operat­
ing instructions provided with the.tester being used.
Check
the
open circuit voltage
(no
load)
of the
bat­
tery. Voltage should
be
equal
to or
greater than
12.4

volts
(Fig. 7)
with green color visible
in
test indica­
tor. 898A-8
INDUCTION

AMPMETER CLAMP
POSITIVE CLAMP NEGATIVE
CLAMP

J908A-12

Fig.
8
Volt-Ammeter-Load Tester
Connections
(3) Rotate
the
load control knob (Carbon pile rheo­
stat)
to
apply
a 300 amp
load
for 15
seconds then
control knob
to off
(Fig.
9).
This will remove
the
sur­
face charge from
the
battery.

Fig.
7
Volt-Amps-Load
Tester—
Typical
898A-10

Fig.
9
Remove
Surface
Charge
from
Battery

(4) Allow
the
battery
to
stabilize
to
open circuit
voltage
(may
take
up to 5
minutes).
(5) Rotate
the
load control knob
to
maintain
a
load

(50%
of
cold crank rating—see specifications)
for a

minimum
15
seconds
(Fig. 10).
After
15
seconds,
record
the
(loaded) voltage reading
and
return
the
load control
to off.

(6) Voltage drop will vary according
to
battery
temperature
at the
time
of the
load test. Battery
temperature
can be
estimated
by the
temperature
of
exposure over
the
preceding several hours.
If the
bat­
tery
has
been charged, boosted,
or
loaded
a few
min­ utes prior
to
test,
the
battery would
be
somewhat
warmer. Refer
to
Load Test Temperature chart
for

proper loaded voltage reading.
(7)
If
battery passes load test,
it is in
good condi­
tion.
No
further tests
are
necessary.
If it
fails load
test,
it
should
be
replaced.

8A
- 6
ELECTRICAL

•

Fig.
10
Load
50%
Cold
Crank
Rating Note Voltage
LOAD TEST TEMPERATURE

Minimum
Voltage
Temperature

Minimum
Voltage

P c°
9.6 70 and
above
21 and
above

9.5 60
16
9.4 50 10
9.3 40 4
9.1 30 -1
8.9 20 -7
8.7 10 -12
8.5 0
•
18

J908A-4

BATTERY
CHARGING
A battery is completely charged when it has:
• an open circuit voltage of 12.4 volts or more.
• has enough cranking capacity (minimum 9.6 volts
when loaded for 15 seconds to 50% of cold cranking amperage rating at 21°C/70°F). A green color, in the test indicator on the top of the
battery, indicates the battery is charged enough for
further testing. A black color indicates the battery
voltage state of charge is below 75%. A yellow or
bright color indicates the battery has excessively low electrolyte level. The battery cannot be refilled or
charged, it must be replaced.

WARNING:
DO NOT
CHARGE
A
BATTERY
THAT
HAS
EXCESSIVELY
LOW
ELECTROLYTE LEVEL.
BATTERY MAY ARC INTERNALLY AND EXPLODE.
WARNING: EXPLOSIVE GASES FORM OVER BAT­

TERY,
DO NOT
SMOKE, USE FLAME,
OR
CREATE
SPARKS
NEAR BATTERY.
WARNING:
DO
NOT ASSIST BOOST
OR
CHARGE
A
FROZEN BATTERY, CASING MAY FRACTURE. WARNING: POISON, CAUSES SEVERE BURNS.
BATTERY CONTAINS SULFURIC ACID, AVOID CON­

TACT WITH
SKIN,
EYES,
OR
CLOTHING.
IN
EVENT OF CONTACT, FLUSH
WITH
WATER
AND
CALL PHYSICIAN IMMEDIATELY. KEEP
OUT OF
REACH
OF CHILDREN.
CAUTION:
Disconnect
the
vehicle's
battery
negative

cable
before
charging
battery to
avoid
damage
to

electrical
systems.
Do not
exceed
16.0
volts
while
charging
battery.
Battery electrolyte will bubble inside of case while
being charged properly. If the electrolyte boils vio­ lently or is discharged from the vent holes while
charging, immediately reduce charging rate or turn
off charger and evaluate battery condition.
Some battery chargers are equipped with polarity
(+ to +/- to -) sensing devices to protect the charger
or battery from being damaged if improperly con­
nected. If the battery state of charge is too low for
the polarity sensor to detect, the sensor must be by­
passed for charger to operate. Refer to operating in­ structions provided with battery charger being used.

CAUTION:
Charge
battery
until
test
indicator
ap­

pears
green.
Do not
overcharge.

It may be necessary to jostle the battery or vehicle
to bring the green ball into view in the test indicator
when the state-of-charge has reached 75%.
BATTERY CHARGING TIME TABLE

Charging
Amperage
5 Amps
10 Amps
20 Amps

Open
Circuit
Voltage
Hours
Charging
at21°C
(70°F)

12.25
to
12.39
6Hrs.
3Hrs.
1.5
Hr.

12.00
to
12.24
8Hrs.
4Hrs.
2Hrs

11.95
to
12.09
12Hrs.

6Hrs.
3Hrs.

10.00
to
11.95
14Hrs.

7Hrs.
3.5 Hrs.
10.00 to
0
See
Charging
Completely

Discharged
Battery

928A-19

After the battery has been charged, green indica­
tor, perform a load test to determine cranking capac­ ity. If the battery will endure a load test, return the
battery to use. If battery will not endure a load test, it must be replaced. Clean and inspect battery hold
downs, tray, terminals, posts, and top before complet­
ing service, see Group 8B - Battery/Starter/Generator Service.
CHARGING TIME REQUIRED The time required to charge a battery will vary de­
pending upon the following factors:

•

ELECTRICAL
8A - 7
(1) Size
of
Battery—
A
completely discharged
large heavy-duty battery requires more than twice
the recharging time
as a
completely discharged small capacity battery.

WARNING: NEVER EXCEED
20
AMPS
WHEN
CHARGING
A
COLD
(-1°C/30°F)
BATTERY,
PER­

SONAL
INJURY
MAY RESULT.
(2) Temperature—
A
longer time will
be
needed
to charge
a
battery
at -18°C (0°F)
than
at
27°C
(80°F).
When
a
fast charger
is
connected
to a
cold
battery, current accepted
by
battery will
be
very
low
at first. Then,
in
time,
the
battery will accept
a

higher rate
as
battery warms.
(3) Charger Capacity—
A
charger that supplies
only
5
amperes requires
a
much longer charging
time than
a
charger that supplies
20
amperes.
(4) State
Of
Charge—
A
completely discharged
battery requires more charging time than
a
partially charged battery. Electrolyte
is
nearly pure water
in a

completely discharged battery.
At
first
the
charging
current amperage will
be low. As
acid
is
forced from
the plates, inside
the
battery,
the
current amperate
will rise. Also,
the
specific gravity
of the
electrolyte will rise, bringing
the
green
dot
into view.

CHARGING
COMPLETELY
DISCHARGED

BATTERY

The following procedure should
be
used
to
recharge
a completely discharged battery. Unless procedure
is

properly followed,
a
good battery
may be
needlessly replaced.
(1) Measure voltage
at
battery posts with
a
volt­
meter, accurate
to 1/10
volt
(Fig, 11). If
below
10

volts,
then charge current will
be low and it
could
take some time before
it
accepts
a
current
in
excess of
a few
milliamperes. Such
low
current
may not be

detectable
on
ammeters built into many chargers.
(2) Connect charger leads. Some chargers feature
polarity protection circuitry which prevents operation
unless charger
is
connected
to
battery posts correctly.
A completely discharged battery
may not
have enough voltage
to
activate
the
protection circuitry,
even though leads
are
connected properly. This
makes
it
appear that battery will
not
accept charging
current. Refer
to
instructions provided with battery
charger being used.
VOLT
SELECTOR

FIELD
SELECTOR
TEST
SELECTOR
898A-12

Fig.
11
Voltmeter
Accurate
to 1/10
Volt
Connected

(3) Battery chargers vary
in the
amount
of
voltage
and current they provide.
For
time required
for
bat­
tery
to
accept measurable charger current
at
various voltages, refer
to
Charge Rate chart.
If
charge, cur­
rent
is
still
not
measurable
at end of
charging times,
the battery should
be
replaced.
If
charge current
is
measurable during charging time,
the
battery
may

be good
and
charging should
be
completed
in the
nor­ mal manner.

Voltage
Hours

16.0
volts
maximum
up
to
4
hrs.
14.0
to
15.9
volts
up
to 8 hrs

13.9
volts
or
less up
to 16
hrs.
J928A-6