1995 JEEP YJ 4 wheel drive

CAUTION: Exercise care during the bearing preload
torque adjustment. Do not over-tighten, or loosen
and then re-tighten the nut. Do not exceed the bear-
ing preload torque. The collapsible preload spacer
on the shaft will have to be replaced. The bearing
preload torque will be re-adjusted afterward.
(4) Install a socket and inch-pound torque wrench
on the pinion nut.
(5) Rotate the shaft with the torque wrench and
note the torque.
The required preload torque is equal to the
amount recorded during removal plus an addi-
tional 0.56 Nzm (5 in. lbs.).
(6) Use Flange Wrench C-3281 to retain the yoke
and shaft (Fig. 5). Tighten the shaft nut in very
small increments.(7) Continue tightening the shaft nut in small in-
crements until the correct bearing preload torque is
attained.
(8) Align the installation reference marks and at-
tach the drive shaft to the yoke.
(9) Add API grade GL 5 hypoid gear lubricant to
the differential housing, if necessary.
(10) Install wheel and tire assemblies.
(10) Lower the vehicle.
AXLE SHAFT
REMOVAL
(1) Raise and support the vehicle.
(2) Remove the wheel and tire.
(3) Remove the brake drum.
(4) Clean all the foreign material from housing
cover area.
(5) Loosen the housing cover bolts. Drain the lubri-
cant from the housing and the axle shaft tubes. Re-
move the housing cover.
(6) Rotate the differential case so that the pinion
mate gear shaft lock screw is accessible. Remove the
lock screw and the pinion mate gear shaft from the
case (Fig. 6).
(7) Force the axle shaft in toward the center of the
vehicle. Remove the axle shaft C-clip lock from the
axle shaft (Fig. 7).
(8) Remove the axle shaft. Use care to prevent
damage to the axle shaft bearing and seal, which will
remain in the axle shaft tube.
(9) Inspect axle shaft seal for leakage or damage.
Fig. 3 Seal Removal
Fig. 4 Pinion Seal Installation
Fig. 5 Tightening Pinion Shaft Nut
3 - 16 REAR SUSPENSION AND AXLESJ

LUBRICANT SPECIFICATIONS
Multi-purpose, hypoid gear lubricant should be
used in the 8 1/4 inch axle. The lubricant should
have MIL-L-2105C and API GL 5 quality specifica-
tions. MOPARtHypoid Gear Lubricant conforms to
both of these specifications.
²The factory installed lubricant for the 8 1/4 inch
rear axle is SAE 80W 90 gear lubricant.
²The factory installed lubricant quantity is 6762
fluid oz.
CAUTION: Overfilling the differential can result in
lubricant foaming and overheating.
Refer to Group 0, Lubrication and Maintenance for
additional information.
CAUTION: If axle is submerged in water, lubricant
must be replaced immediately to avoid possible
premature axle failure.
DRIVE AXLE ASSEMBLY REPLACEMENTÐXJ
VEHICLES
REMOVAL
(1) Raise the vehicle. Position support stands un-
der the frame rails slightly in front the springs.
(2) Remove the rear wheels.
(3) Mark the drive shaft yoke and axle pinion yoke
for alignment reference. Disconnect the drive shaft
from the axle.
(4) Disconnect the axle vent hose.
(5) Disconnect the parking brake cables at the
equalizer or backing plate.
(6) Disconnect the shock absorbers from the axle
brackets.
(7) Disconnect the brake hose at the axle junction
block.Do not disconnect the wheel cylinder tub-
ing fittings.
(8) If equipped, disconnect ABS wiring connections
at the axle.
(9) Support the axle with a hydraulic jack under
the differential.
(10) Remove the spring U-bolts from the plate
brackets.
(11) Lower the jack enough to remove the axle.
INSTALLATION
CAUTION: Suspension components with rubber
bushings should be tightened with the vehicle at
normal height. It is important to have the springs
supporting the weight of the vehicle when the fas-
teners are torqued. If springs are not at their normal
ride position, vehicle ride comfort could be affected
and premature bushing wear may occur. Rubber
bushings must never be lubricated.(1) Support the axle on a hydraulic jack under the
differential. Position the axle under the vehicle.
(2) Raise the axle and align the spring center bolts
with the locating holes in the axle pads and plate
brackets.
(3) Install the spring U-bolts through the plate
brackets and tighten to 70 Nzm (52 ft. lbs.) torque.
(4) Install ABS wiring connections (if equipped) at
the axle.
(5) Connect the brake hose at the axle junction
block.
(6) Install the shock absorbers to the axle brackets
and tighten to 62 Nzm (46 ft. lbs.) torque.
(7) Connect the parking brake cables at the equal-
izer or backing plate.
(8) Connect the vent hose to the tube fitting.
(9) Align the reference marks and connect the
drive shaft to the axle yoke. Tighten the U-joint
clamp bolts to 19 Nzm (14 ft. lbs.) torque.
(10) Check differential lubricant and add if neces-
sary.
(11) Install the wheel and tire.
(12) Bleed the brakes.
(13) Remove the supports and lower the vehicle.
LUBRICANT CHANGE
The gear lubricant will drain quicker if the vehicle
has been recently driven.
(1) Raise and support the vehicle.
(2) Remove the lubricant fill hole plug from the dif-
ferential housing cover.
(3) Remove the differential housing cover and
drain the lubricant from the housing.
(4) Clean the housing cavity with a flushing oil,
light engine oil or lint free cloth.Do not use water,
steam, kerosene or gasoline for cleaning.
(5) Remove the sealant from the housing and cover
surfaces. Use solvent to clean the mating surfaces.
(6) Apply a bead of MOPARtSilicone Rubber Seal-
ant to the housing cover (Fig. 2). Allow the sealant to
cure for a few minutes.
Install the housing cover within 5 minutes after
applying the sealant. If not installed the sealant
must be removed and another bead applied.
(7) Install the cover and any identification tag.
Tighten the cover bolts in a criss-cross pattern to 47
Nzm (35 ft. lbs.) torque.
(8) Refill the differential with Mopar Hypoid Gear
Lubricant 13 mm (1/2 in.) below the fill plug hole.
With Trac-Lok differentials, add a container of Mopar
Hypoid Gear Lubricant Additive.
CAUTION: Overfilling the differential can result in
lubricant foaming and overheating.
(9) Install the fill hole plug and lower the vehicle.
JREAR SUSPENSION AND AXLES 3 - 31

BEARING AND SEAL INSTALLATION
Do not install the original axle shaft seal. Al-
ways install a new seal.
(1) Wipe the bore in the axle shaft tube clean.
(2) If the original bearing is not reusable, install a
new bearing. Place the axle shaft bearing on the pilot
of Bearing Installer C-4198 and Handle C-4171.
CAUTION: DO NOT use the new axle shaft seal to
position or seat the bearing in the axle shaft bore.
(3) Insert the bearing into the tube. Ensure that
the bearing is not cocked and is seated firmly against
the tube shoulder.
(4) Install the new axle shaft seal (Fig. 6) with In-
staller C-4198 and Handle C-4171. The flat side of
the installation tool must face the seal.
(5) When the tool contacts the end of the tube
(face), the seal will be at the correct position and
depth.
AXLE SHAFT INSTALLATION
(1) Lubricate the bearing bore and seal lip. Insert
the axle shaft and engage the splines with the side
gear. Use care to prevent the shaft splines from dam-
aging the axle shaft seal lip.
(2) Insert the C-clip lock in the recessed groove(Fig. 4). Push the axle shaft outward to seat the C-
clip lock.
(3) Insert the pinion gear mate shaft in the case.
Install through the thrust washers and pinion gears.
Align the hole in the shaft with the lock screw hole.
Install the lock screw with Loctiteton the threads.
Tighten the screw to 11 Nzm (8 ft. lbs.) torque (Fig.
3).
(4) Clean the cover and apply a bead of sealant.
Refer to the Drain and Refill in this section.
(5) Install the brake drum and wheel and tire.
(6) Raise or lower the hoist until the vehicle is
level.
(7) Remove the fill hole plug. Fill the differential
housing with lubricant. Refer to the Specifications
chart for the type and the quantity. Install the fill
hole plug.
(8) Lower the vehicle and test the brakes and axle
for correct operation.
PINION SEAL REPLACEMENT
CAUTION: The following procedures must be used
so the correct pinion bearing preload torque is re-
tained. If this procedure is not followed completely,
it may result in premature failure of the rear axle.
REMOVAL
(1) Raise and support the vehicle.
(2) Mark the U-joint, pinion yoke, and pinion shaft
for reference.
(3) Disconnect the drive shaft from the pinion
yoke. Secure the drive shaft in an upright position to
prevent damage to the rear U-joint.
(4) Remove the rear wheels and brake drums to
prevent any drag. The drag can cause a possible false
bearing preload torque measurement.
(5) Use a Newton-meter or an inch-pound torque
wrench to measure the pinion bearing preload. Ro-
tate the pinion shaft several times with the torque
wrench. Note the indicated torque as the wrench is
moved through several revolutions.
This measurement is very important because
the bearing preload torque must be carefully
re-adjusted after the new seal is installed.
(6) Retain the yoke with Wrench C-3281. Remove
the pinion shaft nut and Belleville washer.
(7) Make reference marks and remove the yoke
with a puller.
(8) Lower the rear of the vehicle to prevent lubri-
cant leakage.
(9) Remove the pinion shaft seal with Puller
C-748. Clean the seal contact surface in the housing
bore.
Fig. 5 Axle Shaft Bearing Removal
Fig. 6 Axle Shaft Seal Installation
JREAR SUSPENSION AND AXLES 3 - 33

INSTALLATION
(1) Examine the splines on the pinion shaft for
burrs or wear.
(2) Remove any burrs and clean the shaft.
(3) Inspect the pinion yoke for cracks, worn splines
and a worn seal contact surface. Repair or replace
the yoke as necessary.
The outer perimeter of the seal is pre-coated
with a special sealant. An additional applica-
tion of sealant is not required.
(4) Install the replacement pinion shaft seal (Fig.
7) with Seal Installer C-4076-A and Handle C-4735-1.
The seal is correctly installed when the seal
flange contacts the face of the differential hous-
ing flange.
(5) Position the pinion yoke on the end of the shaft
with the reference marks aligned.
(6) Seat the yoke on the pinion shaft with Installer
C-3718 and Wrench C-3281.
(7) Remove the tools. Install the Belleville washer.
The convex side of the washer must face outward.
(8) Retain the pinion yoke with Wrench C-3281.
Tighten the shaft nut to 285 Nzm (210 ft. lbs.) torque
(Fig. 8). Rotate the pinion shaft several complete rev-
olutions to ensure that the bearing rollers are seated.
Use a Newton-meter or an inch-pound torque
wrench to measure the pinion gear bearing pre-
load torque.
CAUTION: Never loosen pinion gear nut to decrease
pinion gear bearing preload torque and never ex-
ceed specified preload torque. If preload torque is
exceeded a new collapsible spacer must be in-
stalled. The torque sequence will have to be re-
peated.
(9) Continue tightening and measuring the bearing
preload torque until it is the same as the original.The bearing preload torque should never be
greater than 1 Nzm (10 in. lbs.) more than the
recorded value.
The bearing preload torque should be con-
stant during a complete revolution of the pin-
ion gear. If the preload torque varies, this
indicates a binding condition. This condition
must be corrected before the installation of the
drive shaft.
(10) If the specified torque is not obtained, tighten
the nut in small increments until the preload torque
is obtained.
(11) Seal replacement is unacceptable if final nut
torque is less than 285 Nzm (210 ft. lbs.) torque.
(12) Install the drive shaft with the installation
reference marks aligned. Tighten the U-joint yoke
clamp screws to 19 Nzm (14 ft. lbs. or 170 in. lbs.)
torque.
(13) Install the brake drums, wheels and tires.
(14) Adjust the hoist so that the vehicle is in a
level position. Check the differential housing lubri-
cant level. If necessary, add MOPARtHypoid Gear
Lubricant.
DIFFERENTIAL SERVICE
SERVICE INFORMATION
It is not necessary to remove the complete axle to
service the differential.
CAUTION: When differential service is necessary,
both rear wheels must be raised off the surface.
They must be free to rotate.
Fig. 7 Pinion Shaft Seal Installation
Fig. 8 Tightening Pinion Shaft Nut
3 - 34 REAR SUSPENSION AND AXLESJ

BRAKES
CONTENTS
page page
ABS BRAKE DIAGNOSIS................... 3
ABS OPERATION AND SERVICE............ 33
BRAKE FLUIDÐBRAKE BLEEDINGÐ
BRAKELINES AND HOSES............... 10
DISC BRAKES.......................... 45
DRUM BRAKES......................... 55
GENERAL INFORMATION.................. 1MASTER CYLINDERÐCOMBINATION VALVE . . 15
PARKING BRAKES....................... 60
POWER BRAKE BOOSTERÐBRAKE PEDALÐ
BRAKELIGHT SWITCH.................. 22
SERVICE BRAKE DIAGNOSIS............... 4
SPECIFICATIONS........................ 70
GENERAL INFORMATION
INDEX
page page
Antilock Brakes (ABS)....................... 1
Brake Components......................... 1
Brake Fluid/Lubricants/Cleaning Solvents......... 2
Brake Safety Precautions.................... 2Brake Warning Lights....................... 1
Brakelining Material........................ 1
Jeep Body Code Letters..................... 2
BRAKE COMPONENTS
Power assist front disc and rear drum brakes are
standard on Cherokee/Wrangler models. Disc brake
components consist of single piston calipers and ven-
tilated rotors. Rear drum brakes are dual shoe units
with cast brake drums.
The parking brake mechanism is lever and cable
operated. The cables are attached to levers on the
rear drum brake secondary shoes. The parking
brakes are operated by a foot pedal on YJ models and
a hand lever on XJ models.
A 205 mm dual diaphragm vacuum power brake
booster is used for all applications. Two master cylin-
ders are used; 4-cylinder YJ models have a one-piece
master cylinder. All other models have a two-piece
master cylinder with plastic reservoir.
All models are equipped with a combination valve.
The valve contains a pressure differential valve and
switch and a fixed rate rear proportioning valve.
BRAKELINING MATERIAL
Factory brakelining on all models consists of an or-
ganic base material combined with metallic particles.
The lining does not contain asbestos.
BRAKE WARNING LIGHTS
Cherokee/Wrangler models are equipped with one
or two brake warning lights. A red warning light is
standard on all models. An amber light is added on
models with ABS brakes. Both lights are located in
the instrument panel.
The red light is in circuit with the pressure differ-
ential switch (in the combination valve), and with the
parking brake switch. The light alerts the driver
when the parking brakes are applied, or when a
pressure differential exists between the front and
rear hydraulic systems. The light also illuminates for
a few seconds at start up as part of a bulb check.
The ABS warning light is amber in color and is lo-
cated in the same side of the instrument cluster as
the red warning light. The amber light only illumi-
nates when an ABS circuit fault occurs.
ANTILOCK BRAKES (ABS)
An antilock brake system (ABS) is available on
Cherokee/Wrangler models as an option. The system
is an electronically operated, all-wheel brake control
system. The ABS system is designed to prevent
wheel lockup during periods of high wheel slip brak-
ing. Refer to the antilock brake section for operation
and service information.
JBRAKES 5 - 1

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

MASTER CYLINDER/POWER BRAKE BOOSTER
A 25 mm bore master cylinder and 205 mm (8.07
in.) dual diaphragm power brake booster are used for
all ABS applications (Fig. 2).
The master cylinder has a removable plastic reser-
voir which is the only serviceable component. The
cylinder body and pistons are not repairable and are
serviced as an assembly. The check valve and grom-
met are the only serviceable parts on the booster.
The booster itself is only serviced as an assembly.
COMBINATION VALVE
A combination valve is used with the ABS system
(Fig. 2). The valve contains a front/rear brake pres-
sure differential switch and rear brake proportioning
valve. The combination valve is connected between
the master cylinder and HCU.
The pressure differential switch is connected to the
red brake warning light. The switch is actuated by
movement of the switch valve. The switch monitors
fluid pressure in the separate front/rear brake hy-
draulic circuits.
A decrease or loss of fluid pressure in either hy-
draulic circuit will cause the switch valve to shuttle
forward or rearward in response to the pressure dif-
ferential. Movement of the switch valve will push the
switch plunger upward. This closes the switch inter-
nal contacts completing the electrical circuit to the
red warning light. The switch valve remains in an
actuated position until the fault is repaired.
The rear proportioning valve is used to balance front-
rear brake action.
ELECTRONIC CONTROL UNIT (ECU)
A separate electronic control unit (ECU) operates
the ABS system (Fig. 3). The ECU is separate from
other vehicle electrical circuits. ECU voltage source
is through the ignition switch in the Run position.The ECU is located under the instrument panel in
the passenger compartment. On YJ models, it is just
above the heater plenum in line with the glove box.
In left hand drive XJ models, it at the right side of
the steering column. In right hand drive models, it is
near the cowl panel
The ECU contains dual microprocessors. A logic
block in each microprocessor receives identical sensor
signals. These signals are processed and compared si-
multaneously.
The ECU contains a self check program that illu-
minates the ABS warning light when a system fault
is detected. Faults are stored in a diagnostic program
memory and are accessible with the DRB scan tool.
ABS faults remain in memory until cleared, or un-
til after the vehicle is started approximately 50
times. Stored faults arenoterased if the battery is
disconnected.
WHEEL SPEED SENSORS
A speed sensor is used at each wheel. The sensors
convert wheel speed into an electrical signal. This
signal is transmitted to the antilock ECU.
A gear type tone ring serves as the trigger mecha-
nism for each sensor. The tone rings are mounted at
the outboard ends of the front and rear axle shafts.
Different sensors are used at the front and rear
wheels (Fig. 4). The front/rear sensors have the same
electrical values but are not interchangeable.
Fig. 2 ABS Master Cylinder-Booster-Combination
Valve-HCU
Fig. 3 Antilock ECU
5 - 34 ABS OPERATION AND SERVICEJ

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.
ACCELERATION SWITCH
An acceleration switch (Fig. 5), provides an addi-
tional vehicle deceleration reference during 4-wheel
drive operation. The switch is monitored by the an-
tilock ECU at all times. The switch reference signal
is utilized by the ECU when all wheels are deceler-
ating at the same speed.
SYSTEM RELAYS
The ABS system has two relays, which are the
main and motor pump relays. The motor pump relay
is used for the motor pump only. The main relay is
used for the solenoid valves and ECU. The main re-
lay is connected to the ECU at the power control re-
lay terminal. The pump motor relay starts/stops the
pump motor when signaled by the ECU.
IGNITION SWITCH
The antilock ECU and warning light are in standby
mode with the ignition switch in Off or Accessory po-
sition. No operating voltage is supplied to the system
components.A 12 volt power feed is supplied to the ECU and
warning light when the ignition switch is in the Run
position.
SYSTEM WARNING LIGHT
The amber ABS warning light is in circuit with the
ECU and operates independently of the red brake
warning light.
The ABS light indicates antilock system condition.
The light illuminates (flashes) at start-up for the self
check. The light goes out when the self check pro-
gram determines system operation is normal.
ABS SYSTEM POWER-UP AND INITIALIZATION
battery voltage is supplied to the ECU ignition ter-
minal when the ignition switch is turned to Run po-
sition. The ECU performs a system initialization
procedure at this point. Initialization consists of a
static and dynamic self check of system electrical
components.
The static check occurs after the ignition switch is
turned to Run position. The dynamic check occurs
when vehicle road speed reaches approximately 10
kph (6 mph). During the dynamic check, the ECU
briefly cycles the pump and solenoids to verify oper-
ation.
If an ABS component exhibits a fault during initial-
ization, the ECU illuminates the amber warning
light and registers a fault code in the microprocessor
memory.
ABS OPERATION IN NORMAL BRAKING MODE
The ECU monitors wheel speed sensor inputs con-
tinuously while the vehicle is in motion. However,
the ECU will not activate any ABS components as
long as sensor inputs and the acceleration switch in-
dicate normal braking.
Fig. 4 Wheel Speed SensorsFig. 5 Acceleration Switch
JABS OPERATION AND SERVICE 5 - 35