1995 JEEP YJ service

nostic Procedures manual for diagnostic information
and operation of the DRB scan tool.
To test operation of the fan relay only, refer to Re-
laysÐOperation/Testing. This can be found in Group
14, Fuel Systems.
REMOVAL
The auxiliary cooling fan is attached to the radia-
tor upper crossmember behind the radiator.
(1) Remove the two fan mounting bolts from radi-
ator upper crossmember (Fig. 43).
(2) Disconnect the electric fan connector.
(3) Lift fan straight up and out of vehicle.
INSTALLATION
(1) Align lower retaining tabs of fan shroud with
slots in bracket at bottom of radiator. Push fan down
into position.
(2) Tighten the mounting bolts to 4 Nzm (31 in.
lbs.) torque.
(3) Connect auxiliary cooling fan electrical connec-
tor.
TRANSMISSION OIL COOLERS
WATER-TO-OIL COOLER
All models equipped with an automatic transmis-
sion are equipped with a transmission oil cooler
mounted internally within the radiator tank. This in-
ternal cooler is supplied as standard equipment on
all models equipped with an automatic transmission.
Transmission oil is cooled when it passes through
this separate cooler. In case of a leak in the internalradiator mounted transmission oil cooler, engine cool-
ant may become mixed with transmission fluid or
transmission fluid may enter engine cooling system.
Both cooling system and transmission should be
drained and inspected if the internal radiator
mounted transmission cooler is leaking.
Also refer to the section on Transmission Air-to-Oil
Coolers. This auxiliary air-to-oil cooler is an option
on most engine packages.
REPLACING WATER-TO-OIL COOLER IN
RADIATOR SIDE TANK
The internal transmission oil cooler located within
the radiator is not serviceable. If it requires service,
the radiator must be replaced.
Once the repaired or replacement radiator has
been installed, fill the cooling system and inspect for
leaks. Refer to the Refilling Cooling System and Test-
ing Cooling System For Leaks sections in this group.
If the transmission operates properly after repairing
the leak, drain the transmission and remove the
transmission oil pan. Inspect for sludge and/or rust.
Inspect for a dirty or plugged inlet filter. If none of
these conditions are found, the transmission and
torque convertor may not require reconditioning. Re-
fer to Group 21 for automatic transmission servicing.
AIR-TO-OIL COOLER
An auxiliary air-to-oil transmission oil cooler is
available with most engine packages.
On XJ and YJ models, the cooler is located in front
of the radiator or A/C condenser (if equipped) and be-
hind the grill (Figs. 44, 45 or 46). It is mounted to
the front frame crossmember.
Fig. 43 Auxiliary Cooling FanÐRemove/InstallÐ
Typical
Fig. 44 Auxiliary Air-To-Oil CoolerÐYJ Models
7 - 36 COOLING SYSTEM SERVICE PROCEDURESJ

The auxiliary oil coolers on all models operate in
conjunction with the internal radiator mounted main
oil cooler. The transmission oil is routed through the
main cooler first, then the auxiliary cooler, before re-
turning to the transmission.REMOVAL/INSTALLATIONÐXJ MODELS
(1) Remove the grill mounting screws and remove
the grill. Refer to Group 23, Body for procedures.
(2) Place a drain pan below the transmission oil
cooler.
(3) Remove the two hose clamps at oil cooler inlet
and outlet tubes (Figs. 45 or 46).
(4) Remove the two oil cooler mounting bolts (Figs.
45 or 46).
(5) Remove the oil cooler from vehicle.
(6) Reverse the preceding operation for installa-
tion. Tighten the two clamps 2 Nzm (15 in. lbs.)
torque. Tighten mounting bolts to 8 Nzm (72 in. lbs.)
torque.
REMOVAL/INSTALLATIONÐYJ MODELS
(1) Remove fan shroud and radiator. Refer to the
Radiators section for procedures.
(2) Remove the air conditioning filter/drier mount-
ing bolts.
WARNING: BEFORE PROCEEDING WITH THE NEXT
STEP, BE SURE TO WEAR SAFETY GLASSES. THE
A/C SYSTEM IS UNDER PRESSURE EVEN WITH
THE ENGINE OFF.
(3) Remove the A/C condenser mounting bolts (Fig.
47).
(4) Carefully tilt the A/C condenser rearward for
access to the auxiliary transmission oil cooler.
(5) Place a drain pan below the oil cooler.
(6) Remove the two hose clamps at oil cooler inlet
and outlet tubes (Fig. 44).
(7) Remove the three oil cooler mounting bolts
(Fig. 44).
(8) Remove the oil cooler from vehicle.
(9) Reverse the preceding operation for installa-
tion. Tighten the two clamps 2 Nzm (15 in. lbs.)
torque. Tighten mounting bolts to 8 Nzm (72 in. lbs.)
torque.
Fig. 45 Auxiliary Air-To-Oil CoolerÐXJ ModelsÐ4.0L
Engine
Fig. 46 Auxiliary Air-To-Oil CoolerÐXJ ModelsÐ2.5L
Engine
Fig. 47 Condenser Mounting BoltsÐYJ Models
JCOOLING SYSTEM SERVICE PROCEDURES 7 - 37

ENGINE ACCESSORY DRIVE BELTS
INDEX
page page
Automatic Belt TensionerÐXJ Models with Right
Hand Drive............................ 42
Belt Diagnosis............................ 38
Belt Schematics.......................... 38
Belt ServiceÐExcept Right Hand Drive......... 40
Belt ServiceÐXJ Models with Right Hand Drive . . . 42Belt Tension Specifications.................. 38
Belt TensionÐExcept Right Hand Drive (RHD).... 38
Belt TensionÐRight Hand Drive (RHD)......... 38
General Information....................... 38
GENERAL INFORMATION
CAUTION: When installing a serpentine accessory
drive belt, the belt MUST be routed correctly. If not,
the engine may overheat due to water pump rotat-
ing in wrong direction. Refer to the appropriate en-
gine Belt Schematic in this group for the correct
belt routing. Or, refer to the Belt Routing Label lo-
cated in the engine compartment.
BELT DIAGNOSIS
When diagnosing serpentine accessory drive belts,
small cracks that run across the ribbed surface of the
belt from rib to rib (Fig. 1), are considered normal.
These are not a reason to replace the belt. However,
cracks running along a rib (not across) arenotnor-
mal. Any belt with cracks running along a rib must
be replaced (Fig. 1). Also replace the belt if it has ex-
cessive wear, frayed cords or severe glazing.
Refer to the Serpentine Drive Belt Diagnosis charts
for further belt diagnosis.
BELT TENSIONÐEXCEPT RIGHT HAND DRIVE
(RHD)
Correct drive belt tension is required to ensure op-
timum performance of the belt driven engine accesso-
ries. There are different types of adjustment gauges
for checking either a serpentine or a V-type belt. Re-
fer to the instructions supplied with the gauge. Use
the correct gauge when checking belt tension. Place
gauge in the middle of the section of belt being tested
(between two pulleys) to check tension (Figs. 2, 3, 4
or 5). Do not allow the gauge (or gauge adapter) to
contact anything but the belt.
BELT TENSIONÐRIGHT HAND DRIVE (RHD)
XJ MODELS WITH 4.0L 6-CYLINDER ENGINE
It is not necessary to adjust belt tension on RHD
vehicles if equipped with a 4.0L 6-cylinder engine.
The engine is equipped with an automatic belt ten-
sioner (Fig. 7). The tensioner maintains correct belttension at all times.Due to the use of this belt
tensioner, DO NOT attempt to use a belt ten-
sion gauge on this engine.
BELT TENSION SPECIFICATIONS
Refer to the Specifications section at the end of this
group.
BELT SCHEMATICS
The belt routing schematics are published from the
latest information available at the time of publica-
tion.If anything differs between these schemat-
ics and the Belt Routing Label, use the
schematics on Belt Routing Label.This label is
located in the engine compartment.
Refer to figures 2, 3, 4 or 5 for proper belt routing
on vehicles with conventional left hand drive. Refer
to figure 6 for proper belt routing on vehicles with
right hand drive (RHD). Or, refer to the Belt Routing
Label located in the vehicle engine compartment.
Fig. 1 Serpentine Belt Wear Patterns
7 - 38 ENGINE ACCESSORY DRIVE BELTSJ

BELT SERVICEÐEXCEPT RIGHT HAND DRIVE
The following procedures are for models equipped
with conventional left hand drive. Also refer to Belt
ServiceÐWith Right Hand Drive.
REPLACEMENT/ADJUSTMENT
Belt tension is adjusted at the power steering
pump (or idler pulley if not equipped with power
steering). To adjust belt tension or to replace belt:
SERPENTINE DRIVE BELT DIAGNOSIS (CONT.)
Fig. 2 YJ Models with 4.0L Engine, and XJ Models
with 2.5L EngineÐWith A/CFig. 3 YJ Models With 2.5L or 4.0L Engine, and XJ
Models with 2.5L EngineÐWithout A/C
7 - 40 ENGINE ACCESSORY DRIVE BELTSJ

(9) After power steering pump has been tightened
into position, recheck belt tension. Adjust if neces-
sary.
BELT SERVICEÐXJ MODELS WITH RIGHT HAND
DRIVE
The automatic belt tensioner is used only on
XJ models equipped with a 4.0L 6-cylinder en-
gine with right hand drive steering system.
REMOVAL
(1) Attach a socket/wrench to the mounting bolt of
the automatic tensioner pulley (Fig. 7).
(2) Rotate the tensioner assembly clockwise (as
viewed from front) until tension has been relieved
from belt.
(3) Remove belt from idler pulley (Fig. 7) first. Re-
move belt from vehicle.
(4) Check condition and alignment of all pulleys.
INSTALLATION
(1) Position the drive belt over all pulleysexcept
the idler pulley (Fig. 7).
CAUTION: When installing the serpentine accessory
drive belt, the belt must be routed correctly. If not,
the engine may overheat due to the water pump ro-
tating in the wrong direction. Refer to (Fig. 6) for
correct engine belt routing. The correct belt with
the correct length must be used
(2) Attach a socket/wrench to the pulley mounting
bolt of the automatic tensioner (Fig. 7).
(3) Rotate the socket/wrench clockwise (Fig. 7).
Place the belt over the idler pulley. Let tensioner ro-
tate back into place. Remove wrench. Be sure belt is
properly seated in the grooves of all pulleys.
AUTOMATIC BELT TENSIONERÐXJ MODELS WITH
RIGHT HAND DRIVE
The automatic belt tensioner is used only on
XJ models equipped with a 4.0L 6-cylinder en-
gine with right hand drive steering system.
The drive belt is equipped with a spring loaded au-
tomatic belt tensioner (Fig. 10). This belt tensioner
will be used with all belt configurations such as with
or without air conditioning.
REMOVAL
(1) Attach a socket/wrench to the mounting bolt of
the automatic tensioner pulley (Fig. 10).
(2) Rotate the tensioner assembly clockwise (as
viewed from front) until tension has been relieved
from belt.
(3) Remove belt from idler pulley (Fig. 10) first.
Remove belt from automatic tensioner.
(4) Remove tensioner mounting bolt (Fig. 10) from
tensioner bracket. Remove tensioner from vehicle.
Note alignment pin on the back of tensioner.
WARNING: BECAUSE OF HIGH SPRING PRES-
SURE, DO NOT ATTEMPT TO DISASSEMBLE AUTO-
MATIC TENSIONER. UNIT IS SERVICED AS AN
ASSEMBLY (EXCEPT FOR PULLEY).
(5) Remove tensioner pulley bolt. Remove pulley
from tensioner.
Fig. 8 P.S. Pump Rear Mounting BoltsÐTypical
Fig. 9 P.S. Pump Front Mounting Bolt/LocknutÐ
Typical
7 - 42 ENGINE ACCESSORY DRIVE BELTSJ

ELECTRICAL
GROUP INDEX
Group Group
AUDIO SYSTEMS........................ 8F
BATTERY/STARTER/GENERATOR SERVICE.... 8B
BATTERY/STARTING/CHARGING SYSTEMS
DIAGNOSTICS......................... 8A
CHIME/BUZZER WARNING SYSTEMS........ 8U
HORNS................................ 8G
IGNITION SYSTEMS...................... 8D
INSTRUMENT PANEL AND GAUGES......... 8E
LAMPS................................ 8L
OVERHEAD CONSOLE.................... 8C
POWER LOCKS.......................... 8P
POWER MIRRORS....................... 8TPOWER SEATS.......................... 8R
POWER WINDOWS....................... 8S
REAR WINDOW DEFOGGER............... 8N
RESTRAINT SYSTEMS................... 8M
TURN SIGNAL AND HAZARD WARNING
SYSTEMS............................. 8J
VEHICLE SPEED CONTROL SYSTEM......... 8H
WIPER AND WASHER SYSTEMS............ 8K
XJ WIRING DIAGRAMS-LEFT HAND DRIVE . . . 8W
XJ WIRING DIAGRAMS-RIGHT HAND DRIVE . 8W
YJ WIRING DIAGRAMS.................. 8W
BATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICS
CONTENTS
page page
BATTERY............................... 2
CHARGING SYSTEM..................... 17
IGNITION-OFF DRAW.................... 10SPECIFICATIONS........................ 23
STARTING SYSTEM...................... 11
USING ON-BOARD DIAGNOSTIC SYSTEM.... 22
GENERAL INFORMATION
The battery, starting, and charging systems operate
with one another; therefore, they must be tested as a
complete system. In order for the vehicle to start and
charge properly, all of the components involved in
these systems must perform within specifications.
Group 8A covers battery, starting (Fig. 1) and
charging (Fig. 2) system diagnostic procedures. These
procedures include the most basic conventional diag-
nostic methods, to On-Board Diagnostics (OBD) builtinto the Powertrain Control Module (PCM). Use of an
induction milliamp ammeter, volt/ohmmeter, battery
charger, carbon pile rheostat (load tester), and 12-
volt test lamp will be required.
All OBD-sensed systems are monitored by the
PCM. Each monitored circuit is assigned a Diagnos-
tic Trouble Code (DTC). The PCM will store a DTC in
electronic memory for any failure it detects. See Us-
ing On-Board Diagnostic System in this group for
more information.
JELECTRICAL 8A - 1

charged. However, even with these vents, hydrogen
gas can collect in or around the battery. If hydrogen
gas is exposed to flame or sparks, it can ignite.
If the electrolyte level is low, the battery could arc
internally and explode. If the battery is equipped
with removable cell caps, add distilled water when-
ever the electrolyte level is below the top of the
plates. If the battery cell caps cannot be removed, the
battery must be replaced when the electrolyte level is
low.
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.
BATTERY RATINGS
Currently, there are 2 commonly accepted methods
for rating and comparing battery performance. These
ratings are called Cold Cranking Amperage (CCA),
and Reserve Capacity (RC). Be certain that a replace-
ment battery has CCA and RC ratings that equal or
exceed the original equipment specification for the
vehicle being serviced. See Battery Classifications
and Ratings charts in Specifications at the back of
this group.
COLD CRANKING AMPERAGE
The Cold Cranking Amperage (CCA) rating speci-
fies how much current (in amperes) the battery can
deliver for 30 seconds at -17.7ÉC (0ÉF). Terminal volt-
age must not fall below 7.2 volts during or after the
30 second discharge. The CCA required is generally
higher as engine displacement increases, depending
also upon the starter current draw requirements.
RESERVE CAPACITY
The Reserve Capacity (RC) rating specifies the
time (in minutes) it takes for battery terminal volt-
age to fall below 10.2 volts at a discharge rate of 25
amps. RC is determined with the battery fully-
charged at 26.7ÉC (80ÉF). This rating estimates how
long the battery might last after a charging system
failure, under minimum electrical load.
DIAGNOSIS
The battery must be completely charged and the
top, posts, and terminal clamps should be properly
cleaned before diagnostic procedures are performed.
Refer to Group 8B - Battery/Starter/Generator Ser-
vice for more information.
The condition of a battery is determined by two cri-
teria:
(1)State-Of-ChargeThis can be determined by
viewing the built-in test indicator, by checking spe-
cific gravity of the electrolyte (hydrometer test), or by
checking battery voltage (open circuit voltage test).(2)Cranking CapacityThis can be determined
by performing a battery load test, which measures
the ability of the battery to supply high-amperage
current.
If the battery has a built-in test indicator, use this
test first. If it has no test indicator, but has remov-
able cell caps, perform the hydrometer test first. If
cell caps are not removable, or a hydrometer is not
available, perform the open circuit voltage test first.
The battery must be charged before proceeding
with a load test if:
²the built-in test indicator has a black or dark color
visible
²the temperature corrected specific gravity is less
than 1.235
²the open circuit voltage is less than 12.4 volts.
A battery that will not accept a charge is faulty
and further testing is not required. A battery that is
fully-charged, but does not pass the load test is
faulty and must be replaced.
Completely discharged batteries may take
several hours to accept a charge. See Charging
Completely Discharged Battery.
A battery is fully-charged when:
²all cells are gassing freely during charging
²a green color is visible in the sight glass of the
built-in test indicator
²three corrected specific gravity tests, taken at
1-hour intervals, indicate no increase in specific grav-
ity
²open circuit voltage is 12.4 volts or greater.
ABNORMAL BATTERY DISCHARGING
Any of the following conditions can result in abnor-
mal 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, possibly due to equipment installed
after manufacture or repeated short trip use.
(4) Slow driving speeds (heavy traffic conditions) or
prolonged idling with high-amperage draw systems
in use.
(5) Faulty circuit or component causing excessive
ignition-off draw. See Ignition-Off Draw in this group
for diagnosis.
(6) Faulty charging system.
(7) Faulty or incorrect battery.
BUILT-IN TEST INDICATOR
A test indicator (hydrometer) built into the top of
the battery case, provides visual information for bat-
tery testing (Fig. 1). It is important when using the
test indicator that the battery be level and have a
clean sight glass to see correct indications. Additional
light may be required to view indicator.
JBATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICS 8A - 3

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