1995 JEEP YJ Service And Repair Manual

warning lights dead battery open trunk heater remove seats tow key battery

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JEEP YJ 1995 Service And Repair Manual BATTERY DIAGNOSIS
8A - 4 BATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICSJ

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JEEP YJ 1995 Service And Repair Manual WARNING: DO NOT USE OPEN FLAME AS A
SOURCE OF ADDITIONAL LIGHT FOR VIEWING
TEST INDICATOR. EXPLOSIVE HYDROGEN GAS
MAY BE PRESENT IN THE AREA SURROUNDING
BATTERY.
Like a hydrometer, the built-in test i

WARNING: DO NOT USE OPEN FLAME AS A
SOURCE OF ADDITIONAL LIGHT FOR VIEWING
TEST INDICATOR. EXPLOSIVE HYDROGEN GAS
MAY BE PRESENT IN THE AREA SURROUNDING
BATTERY.
Like a hydrometer, the built-in test indicator mea-
sures the specific gravity of the electrolyte. Specific
gravity will indicate battery state-of-charge. How-
ever, the test indicator will not indicate cranking ca-
pacity of the battery. See Load Test in this group for
more information.
Look into the sight glass and note the color of the
indicator (Fig. 2). Refer to the following description,
as the color indicates:
GREENÐindicates 75% to 100% state-of-charge.
The battery is adequately charged for further test-
ing or return to use. If the vehicle will not crank for
a minimum of 15 seconds with a fully-charged bat-
tery, perform Load Test.
BLACK OR DARKÐindicates 0% to 75% state-of-
charge.
The battery is inadequately charged and must be
charged until green indicator (Fig. 2) is visible in
sight glass (12.4 volts or more) before the battery is
tested further or returned to use. See Abnormal Bat-
tery Discharging in this group to diagnose cause of
discharged condition.
YELLOW OR BRIGHTÐindicates low electrolyte
level.
The electrolyte level in the battery is below test in-
dicator (Fig. 2). A maintenance-free battery with non-
removable cell caps must be replaced if electrolyte
level is low. Water can be added to a low-mainte-
nance battery with removable cell caps. A low electro-
lyte level may be caused by an over-charging
condition. See Charging System in this group to di-
agnose an over-charging condition.
WARNING: DO NOT ATTEMPT TO CHARGE, TEST,
OR ASSIST BOOST BATTERY WHEN YELLOW OR
BRIGHT COLOR IS VISIBLE IN SIGHT GLASS OF
TEST INDICATOR. LOW ELECTROLYTE LEVEL CAN
ALLOW BATTERY TO ARC INTERNALLY AND EX-
PLODE. PERSONAL INJURY MAY OCCUR.
HYDROMETER TEST
The hydrometer test reveals the battery state-of-
charge by measuring the specific gravity of the elec-
trolyte. This test cannot be performed on batteries
with non-removable cell caps. If battery has non-re-
movable cell caps, see Built-In Test Indicator or Open
Circuit Voltage Test.
Specific gravity is a comparison of the density of
the electrolyte to the density of pure water. Pure wa-
ter has a specific gravity of 1.000, and sulfuric acid
has a specific gravity of 1.835. Sulfuric acid makes
up approximately 35% of the electrolyte by weight, or
24% by volume.
In a fully-charged battery the electrolyte will have
a temperature corrected specific gravity of 1.260 to
1.290. However, a specific gravity of 1.235 or above is
satisfactory for battery load testing and/or return to
service.
Before testing, visually inspect battery for any
damage (cracked case or cover, loose posts, etc.) that
would cause the battery to be faulty. Then remove
cell caps and check electrolyte level. Add distilled wa-
ter if electrolyte level is below the top of the battery
plates.
To use the hydrometer correctly, hold it with the
top surface of the electrolyte at eye level. Refer to the
hydrometer manufacturer's instructions for correct
use of hydrometer. Remove only enough electrolyte
from the battery so the float is off the bottom of the
hydrometer barrel with pressure on the bulb re-
leased.
Exercise care when inserting the tip of the hydrom-
eter into a cell to avoid damaging the plate separa-
tors. Damaged plate separators can cause premature
battery failure.
Hydrometer floats are generally calibrated to indi-
cate the specific gravity correctly only at 26.7ÉC
(80ÉF). 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 5.5ÉC above 26.7ÉC (10ÉF above
80ÉF), add 4 points. For each 5.5ÉC below 26.7ÉC
(10ÉF below 80ÉF), subtract 4 points. Always correct
Fig. 1 Built-In Test Indicator
Fig. 2 Built-In Test Indicator Sight Glass
JBATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICS 8A - 5

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JEEP YJ 1995 Service And Repair Manual the specific gravity for temperature variation. Test
the specific gravity of the electrolyte in each battery
cell.
Example: A battery is tested at -12.2ÉC (10ÉF) and
has a specific gravity of 1.240.

the specific gravity for temperature variation. Test
the specific gravity of the electrolyte in each battery
cell.
Example: A battery is tested at -12.2ÉC (10ÉF) and
has a specific gravity of 1.240. Determine the actual
specific gravity as follows:
(1) Determine the number of degrees above or be-
low 26.7ÉC (80ÉF):
26.6ÉC - -12.2ÉC = 38.8ÉC (80ÉF - 10ÉF = 70ÉF)
(2) Divide the result from step 1 by 5.5 (10):
38.8ÉC/5.5 = 7 (70ÉF/10 = 7)
(3) Multiply the result from step 2 by the temper-
ature correction factor (0.004):
7 x 0.004 = 0.028
(4) The temperature at testing was below 26.7ÉC
(80ÉF); therefore, the temperature correction is sub-
tracted:
1.240 - 0.028 = 1.212
The corrected specific gravity of the battery in this
example is 1.212.
If the specific gravity of all cells is above 1.235, but
variation between cells is more than 50 points
(0.050), the battery should be replaced.
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) at the end of the charge
period, replace the battery.
When the specific gravity of all cells is above 1.235,
and cell variation is less than 50 points (0.050), the
battery may be load tested.
OPEN CIRCUIT VOLTAGE TEST
A battery open circuit voltage (no load) test will
show state-of-charge of a battery. This test can be
used in place of the hydrometer test if a hydrometer
is not available, or for maintenance-free batteries
with non-removable cell caps.
Before proceeding with this test or load test,
completely charge battery as described in Bat-
tery Charging in this group.
Test battery open circuit voltage as follows:
(1) Before measuring open circuit voltage the sur-
face charge must be removed from the battery. Turn
headlamps on for 15 seconds, then allow up to 5 min-
utes for voltage to stabilize.
(2) Remove both battery cables, negative first.
(3) Using a voltmeter connected to the battery
posts (refer to instructions provided with voltmeter)
measure open circuit voltage (Fig. 3).
See Open Circuit Voltage chart. This voltage read-
ing will indicate state-of-charge, but will not reveal
cranking capacity. If a battery has an open circuit
voltage reading of 12.4 volts or greater, it may be
load tested. A battery that will not endure a load test
is faulty and must be replaced.
LOAD TEST
A battery load test will verify battery cranking ca-
pacity. The test is based on the Cold Cranking Am-
perage (CCA) rating of the battery. See Battery
Classifications and Ratings chart in Specifications, at
the back of this group.
WARNING: IF BATTERY SHOWS SIGNS OF FREEZ-
ING, LEAKING, LOOSE POSTS, OR LOW ELECTRO-
LYTE LEVEL, DO NOT LOAD TEST. PERSONAL
INJURY AND/OR VEHICLE DAMAGE MAY RESULT.
Before performing load test, the battery 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. Open circuit voltage must be 12.4 volts or
greater.
(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. It may take up to 5 minutes for voltage to
stabilize.
OPEN CIRCUIT VOLTAGE
Fig. 3 Testing Open Circuit Voltage
8A - 6 BATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICSJ

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JEEP YJ 1995 Service And Repair Manual (5) Rotate the load control knob to maintain a load
equal to 50% of CCA rating (Fig. 7). After 15 seconds,
record the loaded voltage reading, then return the
load control knob to OFF.
(6) Voltage drop

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JEEP YJ 1995 Service And Repair Manual WARNING: POISONOUS AND CAUSTIC. BATTERY
CONTAINS SULFURIC ACID. AVOID CONTACT WITH
SKIN, EYES, OR CLOTHING. IN EVENT OF CON-
TACT, FLUSH WITH WATER AND CALL PHYSICIAN
IMMEDIATELY. KEEP OUT OF REACH OF

WARNING: POISONOUS AND CAUSTIC. BATTERY
CONTAINS SULFURIC ACID. AVOID CONTACT WITH
SKIN, EYES, OR CLOTHING. IN EVENT OF CON-
TACT, FLUSH WITH WATER AND CALL PHYSICIAN
IMMEDIATELY. KEEP OUT OF REACH OF CHIL-
DREN.
CAUTION: Always disconnect the battery negative
cable before charging battery to avoid damage to
electrical system components. Do not exceed 16.0
volts while charging battery.
Battery electrolyte will bubble inside battery case
during normal battery charging. If the electrolyte
boils, or is discharged from the vent holes while
charging, immediately reduce charging rate or turn
OFF charger and evaluate battery condition.
Battery should not be hot to the touch. If the
battery feels hot to the touch, turn OFF
charger and let battery cool before continuing
charging operation.
Some battery chargers are equipped with polarity
sensing circuitry. This circuitry protects the charger
and/or battery from being damaged if improperly con-
nected.
If the battery state-of-charge is too low for the po-
larity sensing circuitry to detect, the charger will not
operate. This makes it appear that the battery will
not accept charging current. Refer to instructions
provided with the battery charger being used to by-
pass the polarity sensing circuitry.
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, return
the battery to use. If the battery will not endure a
load test, it must be replaced.
Clean and inspect battery holddowns, tray, termi-
nals, posts, and top before completing service. Refer
to Group 8B - Battery/Starter/Generator Service for
more information.
CHARGING TIME REQUIRED
The time required to charge a battery will vary, de-
pending upon the following factors:(1)Battery CapacityÐA completely discharged
heavy-duty battery requires twice the recharging
time of a 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 the battery will be very low at
first. As the battery warms, it will accept a higher
charging current rate.
(3)Charger CapacityÐA charger that supplies
only 5 amperes will require a longer charging time. A
charger that supplies 20 amperes or more requires a
shorter charging time.
(4)State-Of-ChargeÐA completely discharged
battery requires more charging time than a partially
discharged battery. Electrolyte is nearly pure water
in a completely discharged battery. At first, the
charging current (amperage) will be low. As the bat-
tery charges, the specific gravity of the electrolyte
will gradually rise.
CHARGING COMPLETELY DISCHARGED
BATTERY
The following procedure should be used to recharge
a completely discharged battery. Unless this proce-
dure is properly followed, a good battery may be
needlessly replaced.
(1) Measure voltage at battery posts with a voltme-
ter, accurate to 1/10 (0.10) volt (Fig. 8). If the reading
is below 10 volts, the charge current will be low. It
could take some time before the battery accepts a
current greater than a few milliamperes. Such low
current may not be detectable on ammeters built into
many chargers.
(2) Disconnect battery negative cable. Connect
charger leads. Some battery chargers are equipped
BATTERY CHARGING TIME TABLE
Fig. 8 Voltmeter Accurate to 1/10 Volt Connected
8A - 8 BATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICSJ

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JEEP YJ 1995 Service And Repair Manual with polarity sensing circuitry. This circuitry protects
the charger and/or battery from being damaged if im-
properly connected. If the battery state-of-charge is
too low for the polarity sensing cir

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JEEP YJ 1995 Service And Repair Manual IGNITION-OFF DRAW
GENERAL INFORMATION
Ignition-Off Draw (IOD) refers to power being
drained from the battery with the ignition switch
turned OFF. A normal vehicle electrical system will
draw from 5 to

IGNITION-OFF DRAW
GENERAL INFORMATION
Ignition-Off Draw (IOD) refers to power being
drained from the battery with the ignition switch
turned OFF. A normal vehicle electrical system will
draw from 5 to 20 milliamps (0.005 - 0.020 amps).
This is with the ignition switch in the OFF position,
and all non-ignition controlled circuits in proper
working order. The 20 milliamps are needed to sup-
ply PCM memory, digital clock memory, and electron-
ically-tuned radio memory.
A vehicle that has not been operated for approxi-
mately 20 days, may discharge the battery to an in-
adequate level. When a vehicle will not be used for
20 days or more (stored), remove the IOD fuse in the
Power Distribution Center (PDC). This will reduce
battery discharging.
Excessive battery drain can be caused by:
²electrical items left on
²faulty or improperly adjusted switches
²internally shorted generator
²intermittent shorts in the wiring.
If the IOD is over 20 milliamps, the problem must
be found and corrected before replacing a battery. In
most cases, the battery can be charged and returned
to service.
DIAGNOSIS
Testing for high-amperage IOD must be per-
formed first to prevent damage to most milli-
amp meters.
(1) Verify that all electrical accessories are off.
Turn off all lamps, remove ignition key, and close all
doors. If the vehicle is equipped with illuminated en-
try or electronically-tuned radio, allow the systems to
automatically shut off (time out). This may take up
to 3 minutes.
(2) Determine that the underhood lamp is operat-
ing properly, then disconnect or remove bulb.
(3) Disconnect negative cable from battery.
(4) Connect a typical 12-volt test lamp (low-watt-
age bulb) between the negative cable clamp and the
battery negative terminal. Make sure that the doors
remain closed so that illuminated entry is not acti-
vated.The test lamp may light brightly for up to 3 min-
utes, or may not light at all, depending upon the ve-
hicle's electrical equipment. The term brightly, as
used throughout the following tests, implies the
brightness of the test lamp will be the same as if it
were connected across the battery.
The test lamp must be securely clamped to the neg-
ative cable clamp and battery negative terminal. If
the test lamp becomes disconnected during any part
of the IOD test, the electronic timer function will be
activated and all tests must be repeated.
(5) After 3 minutes the test lamp should turn off
or be dimly lit, depending upon the vehicle's electri-
cal equipment. If the test lamp remains brightly lit,
do not disconnect it. Remove each fuse or circuit
breaker (refer to Group 8W - Wiring Diagrams) until
test lamp is either off or dimly lit. This will isolate
each circuit and identify the source of the high-am-
perage draw.
If the test lamp is still brightly lit after disconnect-
ing each fuse and circuit breaker, disconnect the wir-
ing harness from the generator. If test lamp now
turns off or is dimly lit, see Charging System in this
group to diagnose faulty generator. Do not disconnect
the test lamp.
After high-amperage IOD has been corrected, low-
amperage IOD may be checked. It is now safe to in-
stall a milliamp meter to check for low- amperage
IOD.
(6) With test lamp still connected securely, clamp a
milliamp meter between battery negative terminal
and negative cable clamp.
Do not open any doors or turn on any electri-
cal accessories with the test lamp disconnected
or the milliamp meter may be damaged.
(7) Disconnect test lamp. Observe milliamp meter.
The current draw should not exceed 0.020 amp. If
draw exceeds 20 milliamps, isolate each circuit by re-
moving circuit breakers and fuses. The milliamp
meter reading will drop when the source of the draw
is disconnected. Repair this circuit as necessary,
whether a wiring short, incorrect switch adjustment
or a component failure is found.
8A - 10 BATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICSJ

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JEEP YJ 1995 Service And Repair Manual STARTING SYSTEM
GENERAL INFORMATION
The starting system (Fig. 1) consists of:
²ignition switch
²starter relay
²park/neutral position switch (automatic transmis-
sion)
²wiring harness and connectio

STARTING SYSTEM
GENERAL INFORMATION
The starting system (Fig. 1) consists of:
²ignition switch
²starter relay
²park/neutral position switch (automatic transmis-
sion)
²wiring harness and connections
²battery
²starter with an integral solenoid.
Following is a general description of the major
starting system components. Refer to Group 8W -
Wiring Diagrams for complete circuit descriptions
and diagrams.
These components form 2 separate circuits. A high-
amperage feed circuit that feeds the starter up to
300+ amps, and a low-amperage control circuit that
operates on less than 20 amps.
Battery voltage is supplied through the low-amper-
age control circuit to the coil battery terminal of the
starter relay when the ignition switch is turned to
the START position.
If the vehicle is equipped with an automatic trans-
mission, the park/neutral position switch provides a
ground path to the starter relay coil ground terminal.
This switch provides ground only with the transmis-
sion in NEUTRAL or PARK. If the vehicle is
equipped with a manual transmission, the starter re-
lay coil ground terminal is always grounded.
With the starter relay coil now energized, the nor-
mally open relay contacts close. The relay contacts
connect the relay common feed terminal to the relay
normally open terminal. The closed relay contacts en-
ergize the starter solenoid coil windings.
The energized solenoid coils pull-in and hold-in the
solenoid plunger. The solenoid plunger pulls the shiftlever in the starter. This engages the starter overrun-
ning clutch and pinion gear with the flywheel/drive
plate ring gear.
As the solenoid plunger reaches the end of its
travel, the solenoid contact disc completes the high-
amperage starter feed circuit. Current now flows be-
tween the solenoid battery terminal and the starter
motor, energizing the starter.
Once the engine starts, the overrunning clutch pro-
tects the starter from damage by allowing the starter
pinion gear to spin faster than the pinion shaft.
When the driver releases the ignition switch to the
ON position the starter relay coil is de-energized.
This causes the relay contacts to open. When the re-
lay contacts open, the starter solenoid coil is de-ener-
gized.
When the solenoid coil is de-energized, the solenoid
plunger return spring returns the plunger to its re-
laxed position. This causes the contact disc to open
the starter feed circuit, and the shift lever to disen-
gage the overrunning clutch and pinion gear from the
ring gear.
The starter motor and solenoid are serviced only as
a complete assembly. If either component fails, the
entire assembly must be replaced.
DIAGNOSIS
Before removing any unit from the starting system
for repair, perform the following inspections:
INSPECTION
BATTERY INSPECTION
To determine condition of the battery, see Battery
in this group.
WIRING INSPECTION
Inspect wiring for damage. Inspect all connections
at:
²starter solenoid
²park/neutral position switch (automatic transmis-
sion)
²ignition switch
²starter relay
²battery (including all ground connections).
Clean, tighten and repair all connections as re-
quired.
SOLENOID, RELAY AND SWITCH INSPECTIONS
Inspect the solenoid, relay and ignition switch to
determine their condition. Also, if equipped with au-
tomatic transmission, inspect condition of the park/
neutral position switch. Testing information can be
found in the following pages.
Fig. 1 Starting System Components (Typical)
JBATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICS 8A - 11

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