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
air gap should be 0.40 to 1.3 mm (0.0157 to 0.051
in.). If gap is incorrect, the sensor is either loose, or
damaged.
A rear sensor air gap adjustment is only needed
when reinstalling an original sensor. Replacement
sensors have an air gap spacer attached to the sensor
pickup face. The spacer establishes correct air gap
when pressed against the tone ring during installa-
tion. As the tone ring rotates, it peels the spacer off
the sensor to create the required air gap. Rear sensor
air gap is 0.92-1.45 mm (0.036-0.057 in.).
Sensor air gap measurement, or adjustment proce-
dures are provided in this section. Refer to the front,
or rear sensor removal and installation procedures as
required.
FRONT WHEEL SENSOR REMOVAL
(1) Raise vehicle and turn wheel outward for easier
access to sensor.
(2) Remove sensor wire from mounting brackets.
(3) Clean sensor and surrounding area with shop
towel before removal.
(4) Remove bolt attaching sensor to steering
knuckle and remove sensor.
(5) remove sensor wire from brackets on body and
steering knuckle.
(6) Unseat sensor wire grommet in wheel house
panel.
(7) In engine compartment, disconnect sensor wire
connector at harness plug. Then remove sensor and
wire.
FRONT WHEEL SENSOR INSTALLATION
(1) Iforiginalsensor will be installed, wipe all
traces of old spacer material off sensor pickup face.
Use a dry shop towel for this purpose.
(2) Apply Mopar Lock N' Seal or Loctite 242 to bolt
that secures sensor in steering knuckle. Use new
sensor bolt if original bolt is worn or damaged.
(3) Position sensor on steering knuckle. Seat sen-
sor locating tab in hole in knuckle and install sensor
attaching bolt finger tight.
(4) Tighten sensor attaching bolt to 14 Nzm (11 ft.
lbs.) torque.
(5) If original sensor has been installed, check sen-
sor air gap. Air gap should be 0.40 to 1.3 mm (0.0157
to 0.051 in.). If gap is incorrect, sensor is either loose,
or damaged.
(6) Secure sensor wire to steering knuckle and
body brackets.
(7) Route sensor wire forward and behind shock
absorber. Then attach sensor wire to spring seat
bracket with grommets on sensor wire.
(8) Route sensor wire to outer sill bracket. Remove
all twists or kinks from wire.
(9) Attach sensor wire to sill bracket with grom-
met. Be sure wire is free of twists and kinks.(10) Verify sensor wire routing. Wire should loop
forward and above sill bracket. Loose end of wire
should be below sill bracket and towards brake hose.
(11) Seat sensor wire grommet in body panel and
clip wire to brake line at grommet location.
(12) Connect sensor wire to harness in engine com-
partment.
REAR WHEEL SENSOR REMOVAL
(1) On XJ models, raise and fold rear seat forward
for access to rear sensor connectors (Fig. 9).
(2) Disconnect sensors at rear harness connectors.
(3) Push sensor grommets and sensor wires
through floorpan.
(4) Raise vehicle.
(5) Disconnect sensor wires at rear axle connectors.
(6) Remove wheel and tire assembly.
(7) Remove brake drum.
(8) Remove clips securing sensor wires to brake-
lines, rear axle and, brake hose.
(9) Unseat sensor wire support plate grommet.
(10) Remove bolt attaching sensor to bracket and
remove sensor.
REAR WHEEL SENSOR INSTALLATION AND
ADJUSTMENT
(1) Iforiginal sensoris being installed, remove
any remaining pieces of cardboard spacer from sen-
sor pickup face. Use dry shop towel only to remove
old spacer material.
(2) Insert sensor wire through support plate hole.
Then seat sensor grommet in support plate.
(3) Apply Mopar Lock N' Seal or Loctite 242 to
Fig. 9 Acceleration Switch And Rear Sensor
Connections (XJ)
5 - 38 ABS OPERATION AND SERVICEJ
(8) Install transmission. Refer to Group 21 for pro-
cedure.
CLUTCH HOUSING REPLACEMENT
The clutch housing is removable and can be re-
placed when the transmission is out of the vehicle.
The bolts attaching the housing to the transmission
case are located inside the housing (Fig. 8). Recom-
mended tightening torque for the clutch housing-to-
transmission bolts is 38 Nzm (28 ft. lbs.).
Be sure the transmission and housing mating
surfaces are clean before installing an original,
or replacement clutch housing. Dirt/foreign ma-
terial trapped between the housing and trans-
mission will cause misalignment. If
misalignment is severe enough, the result will
be clutch drag, incomplete release and hard
shifting.
CLUTCH HYDRAULIC LINKAGE REMOVAL
The clutch master cylinder, slave cylinder
and connecting line are serviced as an assem-
bly only. The linkage components cannot be
overhauled or serviced separately. The cylin-
ders and connecting line are sealed units. Also
note that removal/installation procedures forright and left hand drive models are basically
the same. Only master cylinder location is dif-
ferent.
(1) Raise vehicle.
(2) Remove fasteners attaching slave cylinder to
clutch housing.
(3) Remove slave cylinder from clutch housing (Fig.
9).
(4) Disengage clutch fluid line from body clips.
(5) Lower vehicle.
(6) Verify that cap on clutch master cylinder reser-
voir is tight. This is necessary to avoid undue spill-
age during removal.
(7) Remove clutch master cylinder attaching nuts.
Note that one nut is accessible from engine compart-
ment and one nut is accessible from under instru-
ment panel (Figs. 10 and 11).
(8) Remove clip securing clutch master cylinder
push rod to pedal and slide push rod off pedal pin.
(9) Disconnect clutch pedal position switch wires.
(10) If pedal pin is equipped with bushing, inspect
condition of bushing and replace it if worn or dam-
aged.
(11) Remove clutch hydraulic linkage through en-
gine compartment.
Fig. 8 Clutch Housing AttachmentFig. 7 Pilot Bearing Installation
JCLUTCH SERVICE 6 - 13
Low coolant level can cause thermostat pellet to be
suspended in air instead of coolant. This will cause
thermostat to open later, which in turn causes higher
coolant temperature. Air trapped in cooling system
also reduces amount of coolant circulating in heater
core resulting in low heat output.
DEAERATION
As the engine operates, any air trapped in cooling
system gathers under the radiator cap. The next time
the engine is operated, thermal expansion of coolant
will push any trapped air past radiator cap into the
coolant reserve/overflow tank. Here it escapes to the
atmosphere into the tank. When the engine cools
down the coolant, it will be drawn from the reserve/
overflow tank into the radiator to replace any re-
moved air.
DRAINING COOLING SYSTEM
ALL MODELSÐEXCEPT XJ WITH 4.0L
6-CYLINDER ENGINE
WARNING: DO NOT REMOVE THE CYLINDER
BLOCK DRAIN PLUGS OR LOOSEN THE RADIATOR
DRAINCOCK WITH SYSTEM HOT AND UNDER
PRESSURE. SERIOUS BURNS FROM COOLANT
CAN OCCUR.
DO NOT WASTE reusable coolant. If the solution
is clean, drain the coolant into a clean container for
reuse.
DO NOT remove the radiator cap when draining
the coolant from the reserve/overflow tank. Open the
radiator draincock and when the tank is empty, re-
move the radiator cap. The coolant does not have to
be removed from the tank unless the system is being
refilled with a fresh mixture.
(1) Drain the coolant from the radiator by loosen-
ing the draincock.
(2) Drain coolant from engine as follows:
(a) On 2.5L 4-cylinder engines (all models) by re-
moving drain plug at left rear side of block.
(b) On 4.0L 6-cylinder engines by removing the
drain plug or coolant temperature sensor on the
left side of the block (Fig. 19).
XJ MODELS WITH 4.0L 6-CYLINDER ENGINE
WARNING: DO NOT REMOVE THE CYLINDER
BLOCK DRAIN PLUGS OR LOOSEN THE RADIATOR
DRAINCOCK WITH SYSTEM HOT AND UNDER
PRESSURE. SERIOUS BURNS FROM COOLANT
CAN OCCUR.
DO NOT WASTE reusable coolant. If the solution
is clean, drain the coolant into a clean container for
reuse.
(1) Remove radiator pressure cap.(2) For access to radiator draincock, remove radia-
tor grille mounting screws and remove grill. Refer to
Group 23, Body for procedures.
(3) Attach one end of a 24 inch long X 1/4 inch ID
hose to the radiator draincock. Put the other end into
a clean container. Open draincock and drain coolant
from radiator.
(4) Drain coolant from engine by removing the
drain plug and coolant temperature sensor on left
side of block (Fig. 19).
REFILLING COOLING SYSTEM
YJ MODELS
(1) Remove draining hose. Tighten the radiator
draincock and the cylinder block drain plug(s).
(2) Fill system using a 50/50 mixture of water and
antifreeze. This is described in the Coolant section of
this group. Fill the radiator to the top and install the
radiator cap. Add sufficient coolant to the reserve/
overflow tank to raise the level to the FULL mark.
(3) Operate the engine with both the radiator cap
and reserve/overflow tank cap in place. After the en-
gine has reached the normal operating temperature,
shut the engine off and allow it to cool.
(4) Add coolant to the reserve/overflow tank as
necessary.Only add coolant when the engine is
cold. Coolant level in a warm engine will be
higher due to thermal expansion.
XJ MODELS
(1) Tighten the radiator draincock and the cylinder
block drain plug(s). If removed, install coolant tem-
perature sensor (4.0L 6-cylinder engine).
(2) Fill system using a 50/50 mixture of water and
antifreeze as described in the Coolant section of this
Fig. 19 Draining CoolantÐ4.0L 6-Cylinder Engine
JCOOLING SYSTEM SERVICE PROCEDURES 7 - 21
WARNING: CONSTANT TENSION HOSE CLAMPS
ARE USED ON MOST COOLING SYSTEM HOSES.
WHEN REMOVING OR INSTALLING, USE ONLY
TOOLS DESIGNED FOR SERVICING THIS TYPE OF
CLAMP, SUCH AS SPECIAL CLAMP TOOL (NUMBER
6094) (FIG. 27). SNAP-ON CLAMP TOOL (NUMBER
HPC-20) MAY BE USED FOR LARGER CLAMPS. AL-
WAYS WEAR SAFETY GLASSES WHEN SERVICING
CONSTANT TENSION CLAMPS.
CAUTION: A number or letter is stamped into the
tongue of constant tension clamps (Fig. 28). If re-
placement is necessary, use only an original equip-
ment clamp with matching number or letter.XJ MODELS WITH 2.5L 4-CYLINDER ENGINE
REMOVAL
(1) Disconnect negative battery cable at battery.
(2) Observe the previousWARNINGS.Remove ra-
diator cap.
(3) Position drain pan under draincock. Open radi-
ator draincock. Drain radiator.
(4) Remove radiator upper and lower hose clamps
(Figs. 27 and 28). Remove hoses.
(5) Remove E-clip from alignment dowel at radia-
tor lower mounting bracket (Fig. 29).
(6) Disconnect coolant reserve/overflow tank hose
from radiator.
(7) Remove four radiator fan shroud mounting
bolts (Fig. 29). Push shroud back against front of en-
gine.
(8) If equipped, disconnect and plug automatic
transmission fluid cooler lines. Refer to Group 21,
Transmission for procedures.
(9) Remove two radiator top mounting bolts (Fig.
29).
(10) (a) If equipped with air conditioning, remove
the radiator grille mounting screws and remove grill.
Refer to Group 23, Body for procedures.
(b) If equipped, remove the air conditioning con-
denser-to-radiator mounting bolt. Use an open end
wrench to remove bottom bolts (Fig. 30).
(11) Lift radiator straight up and out of vehicle.
Take care not to damage radiator fins. When remov-
ing radiator, note position of the rubber seals located
on the top, bottom and sides of radiator (Fig. 29). To
prevent possible overheating, these seals must be in-
stalled to their original positions.
INSTALLATION
(1) Install radiator behind air conditioning con-
denser with bottom alignment dowel inserted into ra-
diator lower mounting bracket (Fig. 29).
(2) Install E-clip to radiator alignment dowel (Fig.
29).
(3) Tighten the four condenser-to-radiator mount-
ing bolts to 6.2 Nzm (55 in. lbs.) torque.
(4) If removed, install radiator grille.
(5) Tighten radiator top mounting bolts to 6 Nzm
(55 in. lbs.) torque.
(6) If equipped, connect automatic transmission
fluid cooler lines to radiator. Refer to Group 21,
Transmission for procedures.
(7) Install the radiator fan shroud.
(8) Connect the coolant reserve/overflow tank hose.
(9) Connect radiator hoses and install hose clamps.
(10) Connect negative battery cable.
(11) Close the draincock.
(12) Fill cooling system with correct coolant.
(13) Install radiator cap.
(14) Check and adjust automatic transmission
fluid level (if equipped).
Fig. 27 Hose Clamp ToolÐTypical
Fig. 28 Clamp Number/Letter Location
JCOOLING SYSTEM SERVICE PROCEDURES 7 - 27
(4) For access to radiator draincock, remove radia-
tor grille mounting screws and remove grill. Refer to
Group 23, Body for procedures.
(5) Attach one end of a 24 inch long X 1/4 inch ID
hose to the radiator draincock. Put the other end into
a clean container. Open draincock and drain radiator.
(6) If equipped, disconnect auxiliary electric cooling
fan electrical connector (Fig. 31).
(7) If equipped, remove two electric cooling fan
mounting bolts. Lift cooling fan straight up until
alignment tabs at the bottom are clear of slots in
bracket at bottom of radiator (Fig. 32).
(8) Remove the two mechanical (non-electrical) fan
shroud mounting bolts. Lift shroud straight up until
alignment tabs at the bottom are clear of slots in
bracket at bottom of radiator (Fig. 32). Place shroud
over mechanical fan.
(9) If equipped, disconnect and plug automatic
transmission fluid cooler lines. Refer to Group 21,
Transmissions for procedures. If equipped with re-
mote transmission cooler, remove line to cooler from
bracket at bottom of radiator.
(10) Disconnect radiator upper and lower hoses
clamps (Figs. 27 and 28). Disconnect radiator upper
and lower hoses.
(11) Mark the position of the hood latch striker on
the radiator crossmember and remove hood latch
striker.(12) Remove two radiator upper crossmember-to-
isolator nuts (Fig. 32).
Fig. 31 Auxiliary Electric Cooling Fan Wiring
ConnectorÐTypical
Fig. 32 Auxiliary Electric Cooling Fan and Fan ShroudÐTypical
JCOOLING SYSTEM SERVICE PROCEDURES 7 - 29
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
OVERHEAD CONSOLE
CONTENTS
page page
DIAGNOSIS............................. 2
GENERAL INFORMATION.................. 1SERVICE PROCEDURES................... 5
GENERAL INFORMATION
An overhead console featuring an electronic com-
pass and thermometer is an available option for XJ
(Cherokee) models. Following are general descrip-
tions of major components used in the overhead con-
sole. Refer to Group 8W - Wiring Diagrams for
complete circuit descriptions and diagrams.
COMPASS
The compass will display the direction in which the
vehicle is pointed using the eight major compass
headings (Examples: north is N, northeast is NE). It
does not display the headings in actual degrees. The
display is turned on or off using the COMP/TEMP
button to the left of the display.
The self-calibrating compass unit requires no ad-
justing in normal use. The only calibration that may
prove necessary is to drive the vehicle in 3 complete
circles, on level ground, in not less than 48 seconds.
This will reorient the unit to its vehicle.
The unit also will compensate for magnetism the
body of the vehicle may acquire during normal use.
However, avoid placing anything magnetic directly on
the roof of the vehicle. Magnetic mounts for an an-
tenna, a repair order hat or a funeral procession flag
can exceed the compensating ability of the compass
unit if placed on the roof panel. Magnetic bit drivers
used on the fasteners that hold the assembly to the
roof header can also affect compass operation.
If the vehicle roof should become magnetized, the
demagnetizing and calibration procedures may be re-
quired to restore proper operation.
THERMOMETER
The thermometer displays the outside ambient
temperature. The temperature displayed can be
changed from Fahrenheit to Celsius using the US/
METRIC button. The displayed temperature is not
an instant reading of conditions, but an average tem-
perature. It may take the unit several minutes to re-
act to a major temperature change such as driving
out of a heated garage into winter temperatures.
When the ignition switch is turned OFF, the lastdisplayed temperature reading stays in memory.
When the ignition switch is turned ON again, the
thermometer will display the memory temperature
for one minute; then update the display to the cur-
rent average temperature reading within five min-
utes.
READING AND COURTESY LAMPS
All reading and courtesy lamps in the overhead
console are activated by the door jamb switches.
When all doors and the liftgate are closed, the lamps
can be individually activated by depressing the corre-
sponding lens. When a door and/or the liftgate is
open, depressing the lamp lens switches will not turn
the lamps off. Refer to Group 8L - Lamps, for diag-
nosis and service of these lamps.
KEYLESS ENTRY RECEIVER
The overhead console houses the keyless entry re-
ceiver. Refer to Group 8P - Power Locks, for diagno-
sis and service of this component.
REMOTE GARAGE DOOR OPENER STORAGE
A compartment in the overhead console is designed
to hold most remote garage door opener transmitters.
The transmitter is mounted within the compartment
with an adhesive-backed hook and loop fastener
patch. Then one to three pegs are selected and
mounted on a post on the inside of the storage com-
partment door. The pegs may be stacked, if neces-
sary. The peg(s) selected must be long enough to
activate the button of the transmitter each time the
storage compartment door is depressed.
SUNGLASSES STORAGE
A flocked storage compartment for sunglasses is in-
cluded in the overhead console. This compartment
features a push/push-type latch and a viscous damp-
ening system for a fluid opening motion.
JOVERHEAD CONSOLE 8C - 1