JEEP CHEROKEE 1994 Service Repair Manual

SPECIFICATIONS
GENERAL INFORMATION
The following specifications are published from the
latest information available at the time of publica-
tion.If anything differs between the specifica-
tions found on the Vehicle Emission Control
Information (VECI) label and the following
specifications, use specifications on VECI label.
The VECI label is located in the engine compart-
ment.
DRIVE BELT TENSION
Belt tension can be adjusted only on models
equipped with conventional left hand drive. Refer to
the following Belt TensionÐExcept RHD Models
chart for specifications.
It is not necessary to adjust belt tension on right
hand drive (RHD) vehicles if equipped with a 4.0L
engine. The engine is equipped with an automatic
belt tensioner. The tensioner maintains correct belt
tension at all times.Due to the use of this belt
tensioner, DO NOT attempt to use a belt ten-
sion gauge on this engine.Refer to Automatic Belt
Tensioner for additional information.
COOLING SYSTEM CAPACITIES
BELT TENSIONÐEXCEPT RHD MODELS
7 - 38 COOLING SYSTEMJ

TORQUE
JCOOLING SYSTEM 7 - 39

ELECTRICAL
GROUP INDEX
Group Group
AUDIO SYSTEMS....................... 8F
BATTERY/STARTER/GENERATOR SERVICE . . 8B
BATTERY/STARTING/CHARGING SYSTEMS
DIAGNOSTICS........................ 8A
CHIME/WARNING BUZZER SYSTEM....... 8U
HORNS............................... 8G
IGNITION SYSTEMS.................... 8D
INSTRUMENT PANEL AND GAUGES........ 8E
LAMPS............................... 8L
OVERHEAD CONSOLE................... 8CPOWER LOCKS........................ 8P
POWER MIRRORS...................... 8T
POWER SEAT.......................... 8R
POWER WINDOWS..................... 8S
REAR WINDOW DEFOGGER.............. 8N
TURN SIGNALS AND HAZARD WARNING
FLASHERS........................... 8J
VEHICLE SPEED CONTROL SYSTEM....... 8H
WINDSHIELD WIPERS AND WASHERS..... 8K
WIRING DIAGRAMS.................... 8W
BATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICS
CONTENTS
page page
BATTERY TEST PROCEDURES............. 2
ENGINE STARTER MOTOR TEST
PROCEDURES ON VEHICLE.............. 9GENERATOR TEST PROCEDURES ON
VEHICLE............................. 14
IGNITION OFF DRAW (IOD) DIAGNOSIS...... 8
USING ON-BOARD DIAGNOSTIC SYSTEM.... 19
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
starting (Fig. 1) and charging (Fig. 2) system diag-
nostic 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 lamp 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.
Fig. 1 Starting System Components (Typical)
JELECTRICAL 8A - 1

BATTERY TEST PROCEDURES
INDEX
page page
Battery Charging.......................... 5
Battery Diagnostics Chart................... 7
Battery Load Test......................... 4
Battery Open Circuit Voltage Test............. 3Battery Testing General Information........... 3
General Information........................ 2
Hydrometer Test.......................... 3
Specifications............................ 8
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 output
over an extended period. A chemical reaction occurs
between the sulfuric acid solution (electrolyte) and
the lead +/þ plates in each cell of the battery. As
the battery discharges, the plates collect the acid
from the electrolyte. 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. The battery is vented to release gases
that are created when the battery is being charged.
The battery top,posts, and terminals should be cleaned when other
underhood maintenance is performed.
WARNING: DO NOT ATTEMPT TO ASSIST BOOST,
CHARGE, OR TEST BATTERY WHEN ELECTRO-
LYTE LEVEL IS BELOW THE TOP OF THE PLATES.
PERSONAL INJURY MAY OCCUR.
When the electrolyte level is below the top of the
plates distilled water should be added. The battery
must be completely charged. The top, posts, and ter-
minals should be properly cleaned before diagnostic
procedures are performed. See Group 8B - Battery/
Starter/Generator Service, for additional information.
Fig. 2 Charging System Components
8A - 2 BATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICSJ

BATTERY TESTING GENERAL INFORMATION
Before testing a battery, clean the top of the
battery case, posts and cable terminals.
Specific gravity is a ratio of the density of the elec-
trolyte and the density of pure water. The electrolyte
is composed of sulfuric acid and water. Acid makes
up approximately 35% of the electrolyte by weight,
or 24% by volume.
The condition of a battery may be determined from
the results of 2 tests:
²hydrometer test
²ability to supply current (battery load test)
Perform the hydrometer test first. If the specific
gravity is less than 1.235, (with battery at room tem-
perature) the battery must be charged before pro-
ceeding with further testing. A battery that will not
accept a charge is defective and further testing is not
necessary.
Completely discharged batteries may take sev-
eral hours to accept a charge. See Charging
Completely Discharged Battery.
A battery that has been fully charged but does not
pass the battery load test is defective.
A battery is fully charged when:
²all cells are gassing freely during charging
²3 corrected specific gravity tests, taken at 1-hour
intervals, indicate no increase in specific gravity.
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 draw sys-
tems in use.
(5) Defective circuit or component causing excess
IOD. Refer to Ignition Off Draw Diagnosis in this
group.
(6) Defective charging system.
(7) Defective battery.
HYDROMETER TEST
Before performing a hydrometer test, remove
battery caps and check electrolyte level. Add
distilled water as required.
Before testing, visually inspect battery for any
damage (cracked case or cover, loose post, etc.) that
would cause the battery to be defective. To use the
hydrometer correctly, hold it with the top surface of
the electrolyte at eye level. Refer to manufacturers
instructions for correct use of hydrometer.
Remove only enough electrolyte from the battery to
keep the float off the bottom of the hydrometer bar-
rel with pressure on the bulb released. Exercise care
when inserting the tip of the hydrometer into a cellto avoid damage to the separators. Damaged separa-
tors can cause premature battery failure.
Hydrometer floats are generally calibrated to indi-
cate the specific gravity correctly only at one fixed
temperature, 80ÉF (26.6ÉC). When testing the specific
gravity at any other temperature, a correction factor
is required.
The correction factor is approximately a specific
gravity value of 0.004, referred to as 4 points of spe-
cific gravity. For each 10ÉF above 80ÉF (5.5ÉC above
26.6ÉC), add 4 points. For each 10ÉF below 80ÉF
(5.5ÉC below 26.6ÉC), subtract 4 points. Always cor-
rect the specific gravity for temperature variation.
Test the specific gravity of the electrolyte in each
battery cell.
Example: A battery is tested at 10ÉF (-12.2ÉC) and
has a specific gravity of 1.240. Determine the actual
specific gravity as follows:
²Determine the number of degrees above or below
80ÉF:
80ÉF - 10ÉF = 70ÉF
²Divide the result above by 10:
70ÉF/10 = 7
²Multiply the result from the previous step by the
temperature correction factor (0.004):
7 x 0.004 = 0.028
²The temperature at testing was below 80ÉF, there-
fore the temperature correction is subtracted:
1.240 - 0.028 = 1.212
²The corrected specific gravity is 1.212.
The fully charged battery should have a tempera-
ture corrected specific gravity of 1.260 to 1.290.
If the specific gravity of all cells is above 1.235,
and cell variation is more than 50 points (0.050), it is
an indication that the battery is unserviceable.
If the specific gravity of one or more cells is less
than 1.235, charge the battery at a rate of approxi-
mately 5 amperes. Continue charging until 3 consec-
utive specific gravity tests, taken at 1 hour intervals,
are constant.
If the cell specific gravity variation is more than 50
points (0.050) after the charge period, replace the
battery.
When the specific gravity of all cells is above 1.235
and variation between cells is less than 50 points
(0.050), the battery may be tested under heavy load.
BATTERY OPEN CIRCUIT VOLTAGE TEST
A battery voltage (no load) test will show state of
charge of a battery that will pass the Battery Load
Test described in this section.Before proceeding
with this test or Battery Load Test, completely
charge battery as described in Battery Charging
in this section.
If a battery has a no load voltage reading of 12.4
volts or greater and will not endure a load test, it is
defective and should be replaced. Refer to Group 8B -
JBATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICS 8A - 3

Battery/Starter/Generator Service for instructions. To
test battery no load voltage, perform the following
operation:
(1) Before measuring open circuit voltage, the sur-
face charge must be removed from plates. Turn head-
lamps 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. 3).
This voltage reading will indicate state of charge,
but will not reveal cranking capacity. Refer to Bat-
tery Open Circuit Voltage chart.
BATTERY LOAD TEST
WARNING: IF BATTERY SHOWS SIGNS OF FREEZ-
ING, LEAKING, LOOSE POSTS, OR LOW ELECTRO-
LYTE LEVEL, DO NOT TEST. ACID BURNS OR
EXPLOSIVE CONDITION MAY RESULT.
A battery load test will verify the cranking ability
based on the cold crank amperage rating of the bat-
tery.
Before performing battery load test, the bat-
tery must be FULLY CHARGED.
(1) Remove both battery cables, negative first. Bat-
tery top and posts should be clean.(2) Connect a suitable volt-ammeter-load tester
(Fig. 4) to the battery posts (Fig. 5). 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. 5).
(3) Rotate the load control knob (carbon pile rheo-
stat) to apply a 300 amp load for 15 seconds then re-
turn the control knob to OFF (Fig. 6). This will
remove the surface charge from the 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 amperage ratingÐsee Specifica-
tions) for a minimum of 15 seconds (Fig. 7). After 15
seconds, record the (loaded) voltage reading and re-
turn the load control knob 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 ambient tem-
perature over the past several hours. If the battery
has been charged, boosted, or loaded a few minutes
prior to test, the battery would be somewhat warmer.
Refer to Load Test Temperature chart for proper
loaded voltage reading.
Fig. 4 Volt-Amps-Load Tester (Typical)
Fig. 5 Volt-Ammeter-Load Tester Connections
BATTERY OPEN CIRCUIT VOLTAGE
Fig. 3 Testing Open Circuit Voltage
8A - 4 BATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICSJ

(7) If the voltmeter reading fell below 9.6 volts,
with the battery temperature at a minimum of 70ÉF
(21ÉC), replace the battery.
BATTERY CHARGING
A battery is completely charged when it has:
²an open circuit voltage of 12.4 volts or more.
²has enough cranking capacity (minimum 9.6 volts
when loaded for 15 seconds to 50% of cold crank am-
perage rating at 21ÉC (70ÉF).
An open circuit voltage of 12.4 volts or greater, in-dicates battery is charged enough for further testing
and possible return to use.
WARNING: DO NOT CHARGE A BATTERY THAT
HAS 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: Always disconnect the 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 case while
being charged properly. If the electrolyte boils or is
discharged from the vent holes while charging, im-
mediately reduce charging rate or turn OFF charger
and evaluate battery condition.
Battery should not be hot to touch.
If the battery feels hot to the touch, turn OFF
charger and let cool before restarting.
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.
Fig. 6 Remove Surface Charge from Battery
Fig. 7 Load 50% Cold Crank Rating Note Voltage
BATTERY CHARGING TIME TABLE
JBATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICS 8A - 5

After the battery has been charged to 12.4 volts or
greater, perform a load test to determine cranking
capacity. If the battery will endure a load test, re-
turn the battery to use. If battery will not endure a
load test, it must be replaced. Clean and inspect bat-
tery holddowns, tray, terminals, posts, and top before
completing 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:
(1)Size of BatteryÐA 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 (-1ÉC/30ÉF) BATTERY, PER-
SONAL INJURY MAY RESULT.
(2)TemperatureÐA longer time will be needed
to charge a battery at -18ÉC (0ÉF) than at 27ÉC
(80ÉF). 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 CapacityÐA charger, that supplies
only 5 amperes, will require a longer charging time
than a charger that supplies 20 amperes or more.
(4)State Of ChargeÐA 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 the battery charges
the specific gravity of the electrolyte will rise slowly.
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. 8). If below 10
volts, then charge current will be low and it could
take some time before it accepts a current greater
than 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 that prevents operation
unless charger is connected to battery posts correctly.
A completely discharged battery may not have
enough voltage to activate this circuitry, even
though leads are connected properly. This makes itappear that battery will not accept charging current.
Refer to instructions provided with battery charger
being used.
(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.
Fig. 8 Voltmeter Accurate to 1/10 Volt Connected
CHARGE RATE
8A - 6 BATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICSJ

BATTERY DIAGNOSTICS CHART
JBATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICS 8A - 7