light JEEP CHEROKEE 1995 Service Owner's Manual

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

AXLE SHAFT, SEAL AND BEARING SERVICE
CAUTION: When rear axle service is necessary,
both rear wheels must be raised off the surface so
that they are free to rotate. Be cautious when the
tires are being rotated by the engine or by other
means.
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 and drain the
lubricant from the housing. Remove 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. 3).
(7) Push the axle shaft in toward the center of the
vehicle. Remove the axle shaft C-clip lock from the
axle shaft (Fig. 4).
(8) Remove the axle shaft. Use care to prevent
damage to the axle shaft bearing, which will remain
in the axle shaft tube.
(9) Inspect the axle shaft bearing contact surface
area for indications of brinelling, spalling, and pit-
ting.
If any of these conditions exist, the axle shaft
and bearing should be replaced. Normal bear-ing contact on the shaft will be a dull gray and
it could appear to be lightly dented.
(10) If any of these conditions exist, the axle shaft
and bearing must be replaced.
The normal appearance (from roller bearing
contact) will be a dull gray surface area that
could appear slightly dented.
AXLE SHAFT SEAL AND BEARING REMOVAL
(1) Remove the axle shaft seal with a small pry
bar.
(2) Remove the bearing if it appears damaged or
the axle shaft shows any of the conditions described
above.
(3) Remove the bearing with Remover C-4167 (Fig.
5). Attach Slide Hammer 7420 and Adapter 7420-8 to
the end of the removal tool.
(4) Inspect the axle shaft seal surface and tube
bore for roughness and burrs.Polish each axle
shaft with No. 600 crocus cloth. This can re-
move slight surface damage. Do not reduce the
diameter of the axle shaft seal contact surface.
When polishing, the crocus cloth should be
moved around the circumference of the shaft
(not in-line with the shaft).
Fig. 2 Typical Housing Cover With Sealant
Fig. 3 Pinion Mate Shaft Lock Screw
Fig. 4 Axle Shaft C-Clip Lock
3 - 32 REAR SUSPENSION AND AXLESJ

CAUTION: Do not subject the bearings, cups, bores
or journals to heat from a torch or other abuse. Per-
manent damage could result. Special tools are
available and recommended when servicing axle.
DIFFERENTIAL CASE REMOVAL
(1) Remove the axle shafts, refer to Axle Shaft Re-
moval.
Side play and runout checks taken during
disassembly will be very useful in reassembly.
(2) Check differential side play. Position a screw-
driver or pinch bar between left side of axle housing
and case flange (Fig. 9). Use a prying motion to de-
termine if any side play exists. There should be no
side play.
Side play resulting from bearing races being
loose on case hubs require replacement of the
differential case. Otherwise, use threaded ad-
juster to remove the side play before measuring
the ring gear runout.
(3) Eliminate any side play in the differential case.
Attach Dial Indicator to Pilot stud C-3288-B. Place
the indicator plunger at a right angle (90É) to the
ring gear (Fig. 10). The plunger should exert a slight
force against the gear face.
(4) Measure runout by turning the ring gear sev-
eral complete revolutions. Observe the dial indicator
pointer. Mark the ring gear and the differential case
at the areas of maximum runout. The ring gear
runout should not exceed 0.13 mm (0.005 inch). If the
runout exceeds 0.13 mm (0.005 inch), a damaged dif-
ferential case could be the cause.Marking the differential case will be very use-
ful later during differential case runout mea-
surement.
(5) Mark the differential housing and differential
bearing caps for installation reference (Fig. 11).
(6) Remove the bearing threaded adjuster lock
from each bearing cap. Loosen the bolts, but do not
remove the bearing caps.
(7) Loosen the threaded adjusters with Wrench
C-4164 (Fig. 12).
(8) Hold the differential case in place. Remove the
bearing caps, adjusters and differential case (Fig. 13).
Each differential bearing cup and threaded
adjuster must be kept with their respective
bearing.
PINION GEAR SHAFT REMOVAL
(1) Remove the pinion gear nut and washer. Use
Puller C-452 and Wrench C-3281 to remove the pin-
ion gear yoke.
Fig. 9 Differential Case Side Play Test
Fig. 10 Ring Gear Runout Measurement
Fig. 11 Housing & Caps Marked For Installation
Reference
JREAR SUSPENSION AND AXLES 3 - 35

(2) Use Puller C-748 to remove pinion seal and dis-
card seal.
(3) Force pinion gear shaft out the front bearing
and remove bearing.This will damage the front
bearing rollers and bearing cup. The front
bearing and cup must be replaced.Discard col-
lapsible spacer.
(4) Remove the front and rear bearing cups.
²Front bearing cup use Remover C-4345 and Han-
dle C-4171
²Rear bearing cup use Remover C-4307 and Handle
C-4171
(5) Remove the rear bearing from the pinion shaft
with Puller C-293-PA (J-29721) and Adapter C-293-42
(Fig. 14). Remove and record the pinion depth shims.
RING GEAR
Do not remove the ring gear from case unless
the runout must be measured.
(1) Clamp the case with the ring gear bolts facing
upward. Use a vise equipped with soft jaws (brass).
(2) Remove and discardleft-handthreaded ring
gear bolts. Use a hammer and a brass drift to force
ring gear loose from the case pilots. Remove the ring
gear.
CASE FLANGE RUNOUT MEASUREMENT
(1) If the ring gear runout exceeded 0.13 mm
(0.005 inch), case flange runout should be measured.
Install the case with bearing cups and threaded ad-
justers close to their original position.
(2) Install the bearing caps and bolts. Tighten the
bolts lightly. Use Wrench C-4164 (Fig. 12) to thread
both adjusters inward. Remove all side play.
(3) Attach Dial Indicator to measure the flange
runout. The plunger should contact the ring squarely
between the outer edge and gear attaching bolt holes
(Fig. 15).
(4) Rotate the differential case several times. Ob-
serve the dial indicator pointer. Mark the area of
maximum flange runout. The differential case flange
runout must not exceed 0.08 mm (0.003 inch). If
runout exceeds this amount replace differential case.
To reduce excessive ring gear runout, posi-
tion gear runout mark 180 degrees opposite
flange runout mark.
(5) Remove differential bearing cap bolts. Remove
differential case from differential housing.
Fig. 12 Threaded Adjuster Tool
Fig. 13 Differential Bearing Cap Removed
Fig. 14 Inner Bearing Removal
3 - 36 REAR SUSPENSION AND AXLESJ

DIFFERENTIAL CASE DISASSEMBLY
(1) Rotate side gears until pinion gears are located
at the differential case opening. Remove gears.
(2) Remove side gears and thrust washers.
(3) Remove differential bearings from the case
hubs with Puller C-293-PA, Adapter C-293-48 and
Plug SP-3289 (Fig. 16).
CLEANING/INSPECTION
(1) Clean all differential components in cleaning
solvent. Allow the bearings to either air dry or dry
them with a lint-free cloth. Dry the other components
with compressed air.
(2) Examine each component for wear or damage.
(3) Replace shims, bearings and cups as a set only.
Replace bearings and cups if either is galled, worn,
cracked, or damaged.
(4) Inspect the differential side and pinion gears.
Replace any gear that is worn, cracked or chipped.
(5) Inspect differential case and replace case if
cracked or damaged.
Polish each axle shaft sealing surface with
No. 600 crocus cloth. This can remove slight
surface damage. Do not reduce the diameter of
the axle shaft seal contact surface. When pol-
ishing, the crocus cloth should be moved
around the circumference of the shaft (not in-
line with the shaft).
When replacing a drive pinion gear bearing,
always replace the bearing and cup as a
matched set.
(6) Inspect the axle shaft C-clip locks for cracks or
excessive wear. Replace them if necessary.
(7) Test each threaded adjuster to determine if it
rotates freely.
(8) If an adjuster binds, repair the damaged
threads or replace the adjuster.
DIFFERENTIAL CASE ASSEMBLY
(1) Lubricate all the differential case components
with gear lubricant.
(2) Place the thrust washers on the differential
side gears. Position the gears in the differential case
counterbores.
If replacement side gears or thrust washers
are used, refer to Differential Side Gear Clear-
ance Measurement And Adjustment (Fig. 17).
(3) Position the thrust washers on the differential
pinion gears. Mesh the pinion gears with the side
gears.Ensure that the pinion gears are exactly
180 degrees opposite each other.
(4) Rotate the side gears to align the pinion gears
and thrust washers. Align these components with the
mate shaft bores in the case.
(5) If ring gear was removed, clean all contact sur-
faces. Use an Arkansas stone or fine file to remove
any sharp areas from the chamfered inside diameter.
Fig. 15 Case Flange Runout Measurement
Fig. 16 Differential Bearing Removal
Fig. 17 Side Gear Calculations
JREAR SUSPENSION AND AXLES 3 - 37

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.
(23) Measure pinion bearing preload torque by ro-
tating pinion shaft with a Newton-meter or an inch-
pound torque wrench. The correct bearing preload
torque is 1 to 2 Nzm (10 to 20 in. lbs.). This torque
value is with replacement bearings and pinion nut
tightened with a minimum of 285 Nzm (210 ft. lbs.)
torque (Fig. 27).
When using original pinion rear bearing and
a replacement front bearing. The correct pre-
load torque is 1 Nzm (10 in. lbs.) in addition to
the torque measured and recorded during dis-
assembly.
The bearing preload torque should be con-
stant during a complete revolution of the pin-
ion gear shaft. If preload torque varies during
rotation of the shaft, there is an internal bind-
ing that must be corrected before final assem-
bly.
(24) If the specified torque is not obtained, tighten
the nut in small increments until the preload torque
is obtained.
The differential will be unacceptable for use
if the final nut torque is less than 285 Nzm (210
ft. lbs.) torque. If the preload torque is not
within the specified range this is also unaccept-
able.
DIFFERENTIAL CASE INSTALLATION
(1) Apply a coating of hypoid gear lubricant to the
differential bearings, bearing cups and threaded ad-
justers. A dab of grease can be used to keep the ad-
justers in position. Carefully position the assembled
differential case in the housing.(2) Observe the reference marks and install the
differential bearing caps at their original locations
(Fig. 28).
(3) Install the bearing cap bolts (Fig. 28). Tighten
the upper bolts to 14 Nzm (10 ft. lbs.) torque. Tighten
the lower bolts finger-tight until the bolt head is
lightly seated.
DIFFERENTIAL BEARING PRELOAD AND RING
GEAR BACKLASH ADJUSTMENT
The following limitations must be considered when
adjusting the differential:
²The maximum ring gear backlash variation is
0.003 inch (0.076 mm).
²Mark the gears so the same teeth are meshed dur-
ing all backlash measurements.
²Maintain the specified threaded-adjuster torque
while adjusting.
²Excessive adjuster torque will introduce a high
bearing load and cause premature bearing failure.
Insufficient adjuster torque can result in excessive
differential case free-play and ring gear noise.
²Insufficient adjuster torque will not support the
ring gear correctly and can cause excessive differen-
tial case free-play and ring gear noise.
The differential bearing cups will not always
immediately follow the threaded adjusters as
they are moved during adjustment. Ensure ac-
curate bearing cup responses to the adjust-
ments. Maintain the gear teeth engaged
(meshed) as marked. The bearings must be
seated by rapidly rotating the pinion gear a
half turn back and forth. Do this five to ten
times each time the threaded adjusters are ad-
justed.
(1) Use Wrench C-4164 to adjust each threaded ad-
juster inward (Fig. 29) until the differential bearing
free-play is eliminated. Allow some ring gear back-
lash (approximately 0.01 inch/0.25 mm) between the
Fig. 27 Bearing Preload Torque Measurement
Fig. 28 Bearing Caps & Bolts
JREAR SUSPENSION AND AXLES 3 - 41

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

SERVICE BRAKE DIAGNOSIS
INDEX
page page
Brake Drag............................... 6
Brake Fade.............................. 6
Brake Fluid Contamination................... 7
Brake Noise.............................. 7
Brake Pull............................... 6
Brake Warning Light Operation................ 5
Brakes Do Not Hold After Driving Through Deep
Water Puddles........................... 7
Component Inspection...................... 5
Contaminated Brakelining.................... 7
Diagnosing Parking Brake Malfunctions.......... 8
Diagnosis Procedures....................... 4
General Information........................ 4Hard Pedal or High Pedal Effort............... 6
Low Pedal............................... 5
Master Cylinder/Power Booster Test............ 8
Pedal Falls Away.......................... 5
Pedal Pulsation (Non-ABS Brakes Only)......... 6
Power Booster Check Valve Test............... 9
Power Booster Vacuum Test.................. 9
Preliminary Brake Check..................... 4
Rear Brake Grab.......................... 7
Road Testing............................. 5
Spongy Pedal............................. 5
Wheel and Tire Problems.................... 7
GENERAL INFORMATION
The diagnosis information in this section covers
service brake components which include:
²disc brake calipers
²disc brakeshoes
²drum brake wheel cylinders
²drum brakeshoes and brake drums
²drum brake support plates
²parking brake mechanism
²master cylinder/combination valve
²vacuum power brake booster
²brake pedal and brakelight switch
²brake warning light
DIAGNOSIS PROCEDURES
Service brake diagnosis involves determining if a
problem is related to a mechanical, hydraulic or vac-
uum operated component. A preliminary brake check,
followed by road testing and component inspection
are needed to determine a problem cause.
Road testing will either verify proper brake opera-
tion or confirm the existence of a problem. Compo-
nent inspection will, in most cases, identify the
actual part responsible for a problem.
The first diagnosis step is the preliminary brake
check. This involves inspecting fluid level, parking
brake action, wheel and tire condition, checking for
obvious leaks or component damage and testing
brake pedal response. A road test will confirm or
deny the existence of a problem. The final diagnosis
procedure involves road test analysis and a visual in-
spection of brake components.
PRELIMINARY BRAKE CHECK
(1) If amber ABS light is illuminated, refer to ABS
Brake System Diagnosis. If red warning light is illu-
minated, or if neither warning light is illuminated,
continue with brake check.(2) Inspect condition of tires and wheels. Damaged
wheels and worn, damaged, or underinflated tires
can cause pull, shudder, tramp and a condition simi-
lar to grab.
(3) If complaint was based on noise when braking,
check suspension components. Jounce front and rear
of vehicle and listen for noise that might be caused
by loose, worn, or damaged suspension or steering
components.
(4) Inspect brake fluid level:
(a) If vehicle has one-piece master cylinder, fluid
level should be within 6 mm (1/4 in.) of reservoir
rim.
(b) If vehicle has nylon reservoir with single
filler cap, correct level is to FULL mark on side of
reservoir. Acceptable level is between FULL and
ADD marks.
(c) Remember that fluid level in the reservoir
compartments will decrease in proportion to nor-
mal lining wear. However, if fluid level is abnor-
mally low, look for leaks at calipers, wheel
cylinders, brakelines and master cylinder.
(5) Inspect brake fluid condition:
(a) Fluid should be free of foreign material.Note
that brake fluid tends to darken over time.
This is normal and should not be mistaken for
contamination. If fluid is clear of foreign ma-
terial, it is OK.
(b) If fluid is highly discolored, or appears to con-
tain foreign material, drain out a sample with a
clean suction gun. Pour sample in a glass container
and note condition described in step (c).
(c) If fluid separates into layers, obviously con-
tains oil, or a substance other than brake fluid,
system seals and cups will have to be replaced and
hydraulic system flushed.
(6) Check parking brake operation. Verify free
movement and full release of cables and foot pedal or
5 - 4 SERVICE BRAKE DIAGNOSISJ

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