transmission repair JEEP CHEROKEE 1995 Service Repair Manual
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Page 54 of 2198
Axle shaft bearings produce noise and vibration
when worn or damaged. The noise generally changes
when the bearings are loaded. Road test the vehicle.
Turn the vehicle sharply to the left and to the right.
This will load the bearings and change the noise
level. Where axle bearing damage is slight, the noise
is usually not noticeable at speeds above 30 mph.
LOW SPEED KNOCK
Low speed knock is generally caused by a worn U-
joint or by worn side-gear thrust washers. A worn
pinion gear shaft bore will also cause low speed
knock.
VIBRATION
Vibration at the rear of the vehicle is usually
caused by a:
²Damaged drive shaft
²Missing drive shaft balance weight
²Worn, out-of-balance wheels
²Loose wheel lug nuts
²Worn U-joint
²Loose spring U-bolts
²Loose/broken springs
²Damaged axle shaft bearings
²Loose pinion gear nut
²Excessive pinion yoke run out²Bent axle shaft
Check for loose or damaged front-end components
or engine/transmission mounts. These components
can contribute to what appears to be a rear-end vi-
bration. Do not overlook engine accessories, brackets
and drive belts.
All driveline components should be examined be-
fore starting any repair.
Refer to Group 22ÐTires And Wheels for addi-
tional information involving vibration diagnosis.
DRIVELINE SNAP
A snap or clunk noise when the vehicle is shifted
into gear (or the clutch engaged), can be caused by:
²High engine idle speed
²Loose engine/transmission/transfer case mounts
²Worn U-joints
²Loose spring mounts
²Loose pinion gear nut and yoke
²Excessive ring gear backlash
²Excessive differential side gear-to-case clearance
The source of a snap or a clunk noise can be deter-
mined with the assistance of a helper. Raise the ve-
hicle on a hoist with the wheels free to rotate.
Instruct the helper to shift the transmission into
gear. Listen for the noise, a mechanics stethoscope is
helpful in isolating the source of a noise.
JFRONT SUSPENSION AND AXLE 2 - 19
Page 95 of 2198
This will load the bearings and change the noise
level. Where axle bearing damage is slight, the noise
is usually not noticeable at speeds above 30 mph.
LOW SPEED KNOCK
Low speed knock is generally caused by a worn
U-joint or by worn side-gear thrust washers. A worn
pinion gear shaft bore will also cause low speed knock.
VIBRATION
Vibration at the rear of the vehicle is usually
caused by a:
²Damaged drive shaft
²Missing drive shaft balance weight
²Worn, out-of-balance wheels
²Loose wheel lug nuts
²Worn U-joint
²Loose spring U-bolts
²Loose/broken springs
²Damaged axle shaft bearings
²Loose pinion gear nut
²Excessive pinion yoke run out
²Bent axle shaft
Check for loose or damaged front-end components
or engine/transmission mounts. These components
can contribute to what appears to be a rear-end vi-
bration. Do not overlook engine accessories, brackets
and drive belts.
All driveline components should be examined be-
fore starting any repair.
Refer to Group 22, Wheels and Tires for additional
information.
DRIVELINE SNAP
A snap or clunk noise when the vehicle is shifted
into gear (or the clutch engaged), can be caused by:
²High engine idle speed
²Loose engine/transmission/transfer case mounts
²Worn U-joints
²Loose spring mounts
²Loose pinion gear nut and yoke
²Excessive ring gear backlash
²Excessive side gear\ase clearance
The source of a snap or a clunk noise can be deter-
mined with the assistance of a helper. Raise the ve-
hicle on a hoist with the wheels free to rotate.
Instruct the helper to shift the transmission into
gear. Listen for the noise, a mechanics stethoscope is
helpful in isolating the source of a noise.
REAR AXLE ALIGNMENT
MEASUREMENT
The following procedure can be used to determine
if abnormal rear tire tread wear is the result of a
bent or deformed rear axle shaft.
(1) Raise both rear wheels off the surface with a
frame contact hoist.
(2) Attach a one-inch long piece of masking tape at
the center of each tire tread for use as reference marks.
(3) Rotate the rear wheels until both reference
marks face the front of the vehicle. Measure the dis-
tance between the outside edges of the two pieces of
tape. Record this measurement as the front of tire
(FTR) measurement.
(4) Rotate the rear wheels until both reference
marks face the rear of the vehicle. Measure the dis-
tance between the outside edges of the two pieces of
tape. Record this measurement as the rear of tire
(RTR) measurement.
(5) Subtract the (RTR) measurement from the
(FTR) measurement to obtain the amount of wheel
toe. The acceptable rear wheel toe-in position is 1/16
inch (1.6 mm) to 3/16 inch (4.8 mm) toe-out.
(6) Rotate the rear wheels until the reference
marks are facing downward. Measure the distance
between the outside edges of the two pieces of tape.
Record this measurement as the bottom of tire (BTR)
measurement.
(7) Average the (FTR) and the (RTR) distance mea-
surements. Subtract the (BTR) measurement from
this average distance to obtain the camber. The ac-
ceptable amount of camber is 1/16 inch to 3/32 inch
(1.6 to 2.4 mm).
(FTR + RTR) DIVIDED BY 2 (TWO) MINUS
BTR EQUALS CAMBER
If the (BTR) distance measurement is less
than the average FTR and RTR distance mea-
surement, the camber will be positive(+).If
the (BTR) distance measurement is greater
than the average FTR and RTR distance, the
camber will be negative(-).
If the toe position or camber is not acceptable, a bent
or deformed rear axle shaft is most likely the cause.
LIMITED SLIP DIFFERENTIAL
Under normal traction conditions, engine torque is di-
vided evenly. With low-traction surfaces, engine torque
is transferred to the wheel with the most tire traction.
When diagnosing a limited-slip differential the wheel
with the least traction can continue spinning.
The most common problem is a chatter noise when
turning corners. Check for incorrect or contaminated
lubricant. Replace the gear lubricant if necessary.
²With Trac-LokŸ differentials add a container of
MOPAR Trac-Lok Lubricant.
This will correct the condition in most instances. If
the chatter persists, clutch damage could have oc-
curred.
After changing the lubricant, drive the vehicle and
make 10 to 12 slow, figure-eight turns. This maneu-
ver will pump lubricant through the clutches.
3 - 10 REAR SUSPENSION AND AXLESJ
Page 130 of 2198
TRAC-LOK DIFFERENTIAL
OPERATION
In a conventional differential, the torque applied to
the ring gear is transmitted to the axle shafts through
the differential gears. During normal operation, the
torque transmitted to each wheel is equal at all times.
However, if one wheel spins, the opposite wheel will
generate only as much torque as the spinning wheel.
In the Trac-Lok differential, part of the ring gear
torque is transmitted through clutch packs. The clutch
packs contain multiple disc. The clutch will have radial
grooves on the plates, and concentric grooves on the
discs or bonded fiber material which is smooth.
In operation, the Trac-Lok clutches are engaged by
two concurrent forces. The first being preload force ex-
erted through Belleville spring washers. The second is
from separating forces generated by the side gears (Fig.
1).
The Trac-Lok design provides the normal differential
action needed for turning corners. It also provides for
the transmission of equal torque to both wheels when
driving straight ahead. When one wheel loses traction,
the clutch packs transfer torque to the wheel having the
most traction. Trac-lok differentials resist wheel spin on
bumpy roads. It also provides more pulling power when
one wheel loses traction. Pulling power is continuous
until both wheels lose traction. If both wheels slip due
to unequal traction, Trac-Lok operation is normal. In ex-
treme cases of differences of traction, the wheel with
the least traction may spin. This occurs after the Trac-
Lok has transferred as much torque as possible to the
non-spinning wheel.
NOISE DIAGNOSIS
If chatter occurs when turning corners, the most
probable cause is incorrect or contaminated lubri-
cant. Before removing the Trac-Lok unit for repair,
drain, flush and refill the axle with the specified lu-
bricant. Refer to Lubricant change in this Group.
A container of Trac-Lok Lubricant (friction modi-
fier) should be added after.
Vehicles with a limited slip differential should be
road tested by making 10 to 12 slow figure-eight
turns. This maneuver will pump the lubricant
through the clutch discs.
Refer to Group 0, Lubrication and Maintenance for
additional information.
DIFFERENTIAL TEST
WARNING: WHEN SERVICING VEHICLES WITH A
LIMITED SLIP DIFFERENTIAL DO NOT USE THE EN-
GINE TO TURN THE AXLE AND WHEELS. BOTH
REAR WHEELS MUST BE RAISED AND THE VEHI-
CLE SUPPORTED. A LIMITED SLIP AXLE CAN EX-
ERT ENOUGH FORCE (IF ONE WHEEL IS IN
CONTACT WITH THE SURFACE) TO CAUSE THE
VEHICLE TO MOVE.
The differential can be tested without removing the
differential case by measuring rotating torque. Make
sure brakes are not dragging during this measure-
ment.
(1) Engine off, transmission in neutral, and park-
ing brake off.
(2) Place blocks in front and rear of both front
wheels.
(3) Jack up one rear wheel until it is completely off
the ground.
(4) Remove wheel and bolt special tool to studs.
Fig. 1 Limited Slip Differential OperationÐBoth
Wheels Driving
JREAR SUSPENSION AND AXLES 3 - 45
Page 140 of 2198
ABS BRAKE DIAGNOSIS
INDEX
page page
ABS Diagnostic Connector................... 3
ABS Warning Light Display................... 3
Antilock ECU and Hcu Diagnosis............... 3
DRB Scan Tool............................ 3General Information........................ 3
Normal Operating Conditions.................. 3
Wheel/Tire Size and Input Signals.............. 3
GENERAL INFORMATION
The DRB scan tool is required for ABS diagnosis.
The scan tool is used to identify ABS circuit faults.
Once a faulty circuit has been identified, refer to
the appropriate chassis/body diagnostic manual for
individual component testing.
ABS WARNING LIGHT DISPLAY
The amber antilock light illuminates at startup as
part of the system self check feature. The light illu-
minates for 2-3 seconds then goes off as part of the
normal check routine.
An ABS circuit fault is indicated when the amber
light remains on after startup, or illuminates during
vehicle operation.
Verify that a fault is actually related to the ABS
system before making repairs. For example, if the
red warning illuminates but the ABS light does not,
the problem is related to a service brake component
and not the ABS system. Or, if neither light illumi-
nates but a brake problem is noted, again, the prob-
lem is with a service brake component and not with
the ABS system.
ABS DIAGNOSTIC CONNECTOR
The ABS diagnostic connector is inside the vehicle.
The connector is the access point for the DRB scan tool.
On XJ models, the connector is located under the
instrument panel to the right of the steering column.
On some models, the connecter may be tucked under
the carpeting on the transmission tunnel. The con-
necter is a black, 6-way type.
On YJ models, the connector is under the instru-
ment panel by the the driver side kick panel. The
connecter is a black, 6 or 8-way type.
The DRB scan tool kit contains adapter cords for
both types of connecter. Use the appropriate cord for
test hookup.
DRB SCAN TOOL
ABS diagnosis is performed with the DRB scan tool.
Refer to the DRB scan tool manual for test hookup and
procedures. Diagnosis information is provided in the ap-
propriate chassis/body diagnostic manual.
WHEEL/TIRE SIZE AND INPUT SIGNALS
Antilock system operation is dependant on accurate
signals from the wheel speed sensors. Ideally, the ve-
hicle wheels and tires should all be the same size
and type. However, the Jeep ABS system is designed
to operate with a compact spare tire installed.
NORMAL OPERATING CONDITIONS
Sound Levels
The hydraulic control unit pump and solenoid valves
may produce some sound as they cycle on and off. This
is a normal condition and should not be mistaken for
faulty operation. Under most conditions, pump and so-
lenoid valve operating sounds will not be audible.
Vehicle Response In Antilock Mode
During antilock braking, the hydraulic control unit
solenoid valves cycle rapidly in response to antilock
electronic control unit signals.
The driver will experience a pulsing sensation
within the vehicle as the solenoids decrease, hold, or
increase pressure as needed. Brake pedal pulsing will
also be noted and is anormal condition.
Steering Response
A modest amount of steering input is required dur-
ing extremely high deceleration braking, or when
braking on differing traction surfaces. An example of
differing traction surfaces would be when the left
side wheels are on ice and the right side wheels are
on dry pavement.
Owner Induced Faults
Driving away with the parking brakes still applied
will cause warning light illumination. Pumping the
brake pedal will also generate a system fault and in-
terfere with ABS system operation.
ANTILOCK ECU AND HCU DIAGNOSIS
An ECU or HCU fault can only be determined
through testing with the DRB scan tool. Do not re-
place either component unless a fault is actually in-
dicated.
JABS BRAKE DIAGNOSIS 5 - 3
Page 142 of 2198
hand lever. Also note if vehicle was being operated
with parking brake partially applied (this will cause
red light to remain on).
(7) Check brake pedal operation. Verify that pedal
does not bind and has adequate free play. If pedal
lacks free play, check pedal and power booster for be-
ing loose or for bind condition. Do not road test until
condition is corrected.
(8) If components inspected look OK, road test ve-
hicle.
ROAD TESTING
(1) If amber warning light is on, problem is with
antilock system component. Refer to antilock diagno-
sis section.
(2) If red warning light is not on, proceed to step
(4).
(3) If red warning light is on, proceed as follows:
(a) See if parking brakes are applied. If brakes
are applied, release them and proceed to step (4).
(b) Note if brake pedal is abnormally low. If
pedal is definitely low and red light is still on,
check front/rear hydraulic circuits for leak.Do not
road test. Inspect and repair as needed.
(4) Check brake pedal response with transmission
in Neutral and engine running. Pedal should remain
firm under steady foot pressure. If pedal falls away,
do not road test as problem is in master cylinder, or
HCU on ABS models. If pedal holds firm, proceed to
next step.
(5) During road test, make normal and firm brake
stops in 25-35 mph range. Note faulty brake opera-
tion such as hard pedal, pull, grab, drag, noise, fade,
etc.
(6) Return to shop and inspect brake components.
Refer to inspection and diagnosis information.
COMPONENT INSPECTION
Fluid leak points and dragging brake units can
usually be located without removing any components.
The area around a leak point will be wet with fluid.
The components at a dragging brake unit (wheel,
tire, rotor) will be quite warm or hot to the touch.
Other brake problem conditions will require compo-
nent removal for proper inspection. Raise the vehicle
and remove the necessary wheels for better visual ac-
cess.
During component inspection, pay particular atten-
tion to heavily rusted/corroded brake components
(e.g. rotors, caliper pistons, brake return/holddown
springs, support plates, etc.).
Heavy accumulations of rust may be covering se-
vere damage to a brake component. It is wise to re-
move surface rust in order to accurately determine
the depth of rust penetration and damage. Light sur-
face rust is fairly normal and not a major concern (as
long as it is removed). However, heavy rust buildup,especially on high mileage vehicles may cover struc-
tural damage to such important components as
brakelines, rotors, support plates, and brake boost-
ers. Refer to the wheel brake service procedures in
this group for more information.
BRAKE WARNING LIGHT OPERATION
The red brake warning light will illuminate under
the following conditions:
²for 2-3 seconds at startup as part of normal bulb
check
²when parking brakes are applied
²low pedal caused by leak in front/rear brake hy-
draulic circuit
If the red light remains on after startup, first ver-
ify that the parking brakes are fully released. Then
check pedal action and fluid level. A red light plus
low pedal indicates the pressure differential switch
and valve have been actuated due to a system leak.
On models with ABS brakes, the amber warning
light only illuminates when an ABS malfunction has
occurred. The ABS light operates independently of
the red warning light.
PEDAL FALLS AWAY
A brake pedal that falls away under steady foot
pressure is generally the result of a system leak. The
leak point could be at a brakeline, fitting, hose,
wheel cylinder, or caliper. Internal leakage in the
master cylinder caused by worn or damaged piston
cups, may also be the problem cause.
If leakage is severe, fluid will be evident at or
around the leaking component. However internal
leakage in the master cylinder will not be physically
evident. Refer to the cylinder test procedure at the
end of this section.
LOW PEDAL
If a low pedal is experienced, pump the pedal sev-
eral times. If the pedal comes back up, worn lining
and worn rotors or drums are the most likely causes.
However, if the pedal remains low and the red warn-
ing light is on, the likely cause is a leak in the hy-
draulic system.
A decrease in master cylinder fluid level may only
be the result of normal lining wear. Fluid level will
drop somewhat as lining wear occurs. It is a result of
the outward movement of caliper and wheel cylinder
pistons to compensate for normal wear.
SPONGY PEDAL
Air in the system is the usual cause of a spongy
pedal. Brake drums machined way beyond allowable
limits (too thin), or substandard brake lines and
hoses can also cause a condition similar to a spongy
JSERVICE BRAKE DIAGNOSIS 5 - 5
Page 238 of 2198
SERVICE PROCEDURES
INDEX
page page
Auxiliary Electric Cooling FanÐXJ Models with 4.0L
6-Cylinder Engine....................... 35
Coolant................................. 20
Coolant Reserve/Overflow System............. 24
Cooling System Cleaning/Reverse Flushing...... 22
Cooling System Fans...................... 32
Cooling System Hoses..................... 32
Draining Cooling System.................... 21
Radiator Pressure Cap..................... 25
Radiators............................... 26Refilling Cooling System.................... 21
Testing Cooling System for Leaks............. 22
Thermostat.............................. 17
Transmission Oil Coolers.................... 36
Viscous Fan Drive......................... 34
Water Pump Tests......................... 13
Water PumpsÐGeneral Information............ 13
Water PumpsÐRemoval/Installation........... 14
WATER PUMPSÐGENERAL INFORMATION
A centrifugal water pump circulates coolant
through the water jackets, passages, intake manifold,
radiator core, cooling system hoses and heater core.
The pump is driven from the engine crankshaft by a
drive belt on all engines.
The water pump impeller is pressed onto the rear
of a shaft that rotates in bearings pressed into the
housing. The housing has a small hole to allow seep-
age to escape. The water pump seals are lubricated
by the antifreeze in the coolant mixture. No addi-
tional lubrication is necessary.
CAUTION: All engines are equipped with a reverse
(counter-clockwise) rotating water pump and vis-
cous fan drive assembly. REVERSE is stamped or
imprinted on the cover of the viscous fan drive and
inner side of the fan. The letter R is stamped into
the back of the water pump impeller (Fig. 1).
Engines from previous model years, depending
upon application, may have been equipped with a for-
ward (clockwise) rotating water pump. Installation of
the wrong water pump will cause engine overheating.
A quick test to determine if the pump is working is
to check if the heater warms properly. A defective wa-
ter pump will not be able to circulate heated coolant
through the long heater hose to the heater core.
WATER PUMP TESTS
LOOSE IMPELLER
DO NOT WASTE reusable coolant. If solution is
clean, drain coolant into a clean container for reuse.
WARNING: DO NOT REMOVE THE CYLINDER
BLOCK DRAIN PLUGS OR LOOSEN THE RADIATOR
DRAINCOCK WITH THE SYSTEM HOT AND UNDER
PRESSURE. SERIOUS BURNS FROM THE COOL-
ANT CAN OCCUR.(1) Drain the cooling system.
(2) Loosen the fan belt(s).
(3) Disconnect the lower radiator hose from the
water pump.
(4) Bend a stiff clothes hanger or welding rod as
shown in (Fig. 2).
(5) Position the rod in the water pump inlet and
attempt to hold the impeller while turning the fan
blades. If equipped with a viscous fan drive, turn the
water pump shaft with a breaker bar and socket at-
tached to a mounting flange nut. If the impeller is
loose and can be held with the rod while the fan
blades are turning, the pump is defective. If the im-
peller turns, the pump is OK.
Connect the hose and install the coolant, or proceed
with repairs.
Fig. 1 Reverse Rotating Water PumpÐTypical
JCOOLING SYSTEM SERVICE PROCEDURES 7 - 13
Page 248 of 2198
WARNING: HOT, PRESSURIZED COOLANT CAN
CAUSE INJURY BY SCALDING.
Carefully remove the radiator pressure cap from
the filler neck and check the coolant level. Push
down on the cap to disengage it from the stop tabs.
Wipe the inner part of the filler neck and examine
the lower inside sealing seat for nicks, cracks, paint,
dirt and solder residue. Inspect the reserve/overflow
tank tube for internal obstructions. Insert a wire
through the tube to be sure it is not obstructed.
Inspect the cams on the outside part of the filler
neck. If the cams are bent, seating of pressure cap
valve and tester seal will be affected. Replace cap if
cams are bent.
Attach pressure tester 7700 (or an equivalent) to
the radiator filler neck (Fig. 21).Operate the tester pump to apply 124 kPa (18 psi)
pressure to the system. If the hoses enlarge exces-
sively or bulge while testing, replace as necessary.
Observe the gauge pointer and determine the condi-
tion of the cooling system according to the following
criteria:
²Holds Steady: If the pointer remains steady for
two minutes, there are no serious coolant leaks in
the system. However, there could be an internal leak
that does not appear with normal system test pres-
sure. Inspect for interior leakage or do the Internal
Leakage Test. Do this if it is certain that coolant is
being lost and no leaks can be detected.
²Drops Slowly: Shows a small leak or seepage is oc-
curring. Examine all connections for seepage or slight
leakage with a flashlight. Inspect the radiator, hoses,
gasket edges and heater. Seal any small leak holes
with a Sealer Lubricant or equivalent. Repair leak
holes and reinspect the system with pressure ap-
plied.
²Drops Quickly: Shows that a serious leakage is oc-
curring. Examine the system for serious external
leakage. If no leaks are visible, inspect for internal
leakage. Large radiator leak holes should be repaired
by a reputable radiator repair shop.
INTERNAL LEAKAGE INSPECTION
Remove the engine oil pan drain plug and drain a
small amount of engine oil. Coolant, being heavier
than engine oil, will drain first. Another way of test-
ing is to operate the engine and check for water glob-
ules on the engine oil dipstick. Also inspect the
automatic transmission oil dipstick for water glob-
ules. Inspect the automatic transmission fluid cooler
for leakage. Operate the engine without the pressure
cap on the radiator until thermostat opens.
Attach a pressure tester to the filler neck. If pres-
sure builds up quickly, a leak exists as a result of a
faulty cylinder head gasket or crack in the engine.
Repair as necessary.
WARNING: DO NOT ALLOW PRESSURE TO EX-
CEED 124 KPA (18 PSI). TURN THE ENGINE OFF.
TO RELEASE THE PRESSURE, ROCK THE TESTER
FROM SIDE TO SIDE. WHEN REMOVING THE
TESTER, DO NOT TURN THE TESTER MORE THAN
1/2 TURN IF THE SYSTEM IS UNDER PRESSURE.
If there is no immediate pressure increase, pump
the pressure tester until the indicated pressure is
within the system range. Vibration of the gauge
pointer indicates compression or combustion leakage
into the cooling system.
WARNING: DO NOT DISCONNECT THE SPARK
PLUG WIRES WHILE THE ENGINE IS OPERATING.
Fig. 20 Leak Detection Using Black LightÐTypical
Fig. 21 Pressurizing SystemÐTypical
JCOOLING SYSTEM SERVICE PROCEDURES 7 - 23
Page 261 of 2198
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
Page 282 of 2198
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
Page 286 of 2198
Remove starter relay from PDC to perform the fol-
lowing tests:
(1) A relay in the de-energized position should
have continuity between terminals 87A and 30, and
no continuity between terminals 87 and 30. If OK, go
to next step. If not OK, replace faulty relay.
(2) Resistance between terminals 85 and 86 (elec-
tromagnet) should be 7565 ohms. If OK, go to next
step. If not OK, replace faulty relay.
(3) Connect a battery to terminals 85 and 86.
There should now be continuity between terminals
30 and 87, and no continuity between terminals 87A
and 30. If OK, go to Relay Circuit Test. If not OK,
replace faulty relay.
RELAY CIRCUIT TEST
(1) The common feed terminal (30) is connected to
battery voltage and should be hot at all times. If OK,
go to next step. If not OK, check circuit to fuse (F4
for YJ, F10 for XJ) in Power Distribution Center
(PDC). Repair as required.
(2) The normally closed terminal (87A) is con-
nected to terminal 30 in the de-energized position,
but is not used for this application. Go to next step.
(3) The normally open terminal (87) is connected to
the battery terminal (30) in the energized position.
This terminal supplies battery voltage to the starter
solenoid field coils. There should be continuity be-
tween cavity for relay terminal 87 and the starter so-
lenoid terminal at all times. If OK, go to next step. If
not OK, repair circuit to solenoid as required.
(4) The coil battery terminal (86) is connected to
the electromagnet in the relay. It is energized when
the ignition switch is in the START position. Check
for battery voltage at cavity for relay terminal 86with ignition switch in the START position. If OK, go
to next step. If not OK, refer to Group 8D - Ignition
Systems for testing and service of the ignition switch.
(5) The coil ground terminal (85) is connected to
the electromagnet in the relay. On vehicles with an
automatic transmission, it is grounded through the
park/neutral position switch. On vehicles with a
manual transmission, it is grounded at all times.
Check for continuity to ground at cavity for relay ter-
minal 85. If not OK and vehicle has manual trans-
mission, repair circuit as required. If not OK and
vehicle has automatic transmission, refer to Group
21 - Transmission and Transfer Case for testing and
service of the park/neutral position switch.
Fig. 9 Power Distribution CenterÐXJ
Fig. 10 Power Distribution CenterÐYJ
STARTER RELAY CONNECTIONS
JBATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICS 8A - 15