2003 JEEP GRAND CHEROKEE wir

STANDARD PROCEDURE - MASTER CYLINDER
BLEEDING PROCEDURE
A new master cylinder should be bled before instal-
lation on the vehicle. Required bleeding tools include
bleed tubes and a wood dowel to stroke the pistons.
Bleed tubes can be fabricated from brake line.
(1) Mount master cylinder in vise with brass jaws.
(2) Attach bleed tubes to cylinder outlet ports.
Then position each tube end into the bottom of the
reservoir (Fig. 50).
(3) Fill reservoir with fresh brake fluid.
(4) Press cylinder pistons inward with wood dowel.
Then release pistons and allow them to return under
spring pressure. Continue bleeding operations until
air bubbles are no longer visible in fluid.
REMOVAL
(1) Remove the wire connector from the brake fluid
level sensor.
(2) Remove brake lines from master cylinder.
(3) Remove nuts that attach master cylinder to
booster studs (Fig. 51).
(4) Remove master cylinder from booster.
INSTALLATION
NOTE: Bleed new master cylinder on bench before
installation, refer to Service Procedures.
(1) Have an assistant depress the brake pedal
while guiding the master cylinder on the booster rod
and mounting studs.
CAUTION: Do not depress brake pedal too hard and
ensure the booster rod is in the master cylinder pis-
ton or booster/master cylinder damage will occur.(2) Install master cylinder mounting nuts and
tighten nuts to 25 N´m (18 lb. lbs.).
NOTE: Use original or factory replacement nuts only.
(3) Install brake lines and tighten to 16 N´m (144
in. lbs.).
(4) Install fluid level sensor connector.
(5) Fill and bleed brake system.
PEDAL
DESCRIPTION
DESCRIPTION - STANDARD PEDAL
A suspended-type brake pedal is used, the pedal
pivots on a shaft mounted in the pedal support
bracket. The bracket is attached to the dash panel.
The brake pedal assembly and pedal pad are the
only serviceable component.
DESCRIPTION - ADJUSTABLE PEDALS
The Adjustable Pedals System (APS) is designed to
enable the fore and aft repositioning of the brake and
accelerator pedals. This results in improved ergonom-
ics in relation to the steering wheel for taller and
shorter drivers. Being able to adjust the pedal posi-
Fig. 50 Master Cylinder Bleeding
1 - BLEEDING TUBES
2 - RESERVOIR
Fig. 51 Master Cylinder Mounting
1 - MOUNTING NUT
2 - SENSOR CONNECTOR
3 - MOUNTING NUT
4 - BRAKE LINES
WJBRAKES - BASE 5 - 25
MASTER CYLINDER (Continued)

STANDARD PROCEDURE - DISC ROTOR
MACHINING
CAUTION: For vehicles equipped with the Quadra-
Drive System, consisting of the NV-247 transfer case
and a Vari-Lok differential in the front and rear axles,
the following steps must be done prior to the use of a
hub mounted on-vehicle brake lathe. Disconnect the
driveshaft (Refer to 3 - DIFFERENTIAL & DRIVELINE/
PROPELLER SHAFT/PROPELLER SHAFT - REMOVAL)
from the respective axle on which the brake rotors are
being machined. Temporarily remove both brake cali-
pers (Refer to 5 - BRAKES/HYDRAULIC/MECHANICAL/
DISC BRAKE CALIPERS - REMOVAL) from the axle
while disc rotor machining is in process. Both steps
will prevent unnecessary loads to the hub mounted
on-vehicle lathe and speed machining times. Install a
thread lock material to the driveshaft attaching bolts
when reinstalling (Refer to 3 - DIFFERENTIAL & DRIV-
ELINE/PROPELLER SHAFT/PROPELLER SHAFT -
INSTALLATION).
NOTE: A hub mounted on-vehicle lathe is recom-
mended. This type of lathe trues the rotor to the vehi-
cles hub/bearing.
The disc brake rotor can be machined if scored or
worn. The lathe must machine both sides of the rotor
simultaneously with dual cutter heads. The rotor
mounting surface must be clean before placing on the
lathe. Equipment capable of machining only one side at
a time may produce a tapered rotor.
CAUTION: Brake rotors that do not meet minimum
thickness specifications before or after machining
must be replaced.
REMOVAL
REMOVAL - FRONT DISC BRAKE ROTOR
NOTE: Front rotors and hub/bearings are matched
mounted for minimum lateral runout. Before removing
the rotor, mark the rotor and hub/bearing to maintain
original orientation.
(1) Raise and support the vehicle.
(2) Remove wheel and tire assembly.
(3) Remove the caliper anchor bolts (Fig. 64) and
remove the caliper and anchor as an assembly from the
steering knuckle.
(4) Secure caliper anchor assembly to nearby suspen-
sion part with a wire.Do not allow brake hose to
support caliper weight.
(5) Mark the rotor and hub/bearing to maintain orig-
inal orientation. Remove retainers securing rotor to hub
studs.
(6) Remove rotor from hub/bearing.
REMOVAL - REAR DISC BRAKE ROTOR
(1) Raise and support the vehicle.
(2) Remove wheel and tire assembly.
(3) Remove the caliper anchor bolts (Fig. 65).
(4) Remove caliper and anchor as an assembly.(5) Secure caliper anchor assembly to nearby suspen-
sion part with wire.Do not allow brake hose to sup-
port caliper weight.
(6) Remove retainers securing rotor to axle studs.
(7) Remove rotor off axle studs.
Fig. 64 Caliper Anchor Bolts
1 - KNUCKLE
2 - ANCHOR
3 - ANCHOR BOLTS
4 - ROTOR
Fig. 65 Caliper Anchor Bolts
1 - ROTOR
2 - ANCHOR
3 - ANCHOR BOLTS
WJBRAKES - BASE 5 - 33
ROTORS (Continued)
2002 WJ Service Manual
Publication No. 81-370-02064
02WJ5-33 June, 2002

INSTALLATION
INSTALLATION - FRONT DISC BRAKE ROTOR
NOTE: If a new rotor is installed it must be match
mounted to the hub/bearing.
(1) Install rotor on hub studs in its original loca-
tion.
(2) Install the caliper anchor assembly on the
knuckle. Install anchor bolts and tighten to 90-115
N´m (66-85 ft. lbs.).
(3) Install wheel and tire assembly.
(4) Remove support and lower the vehicle.
(5) Pump brake pedal to seat caliper pistons and
brake shoes. Do not move vehicle until firm brake
pedal is obtained.
INSTALLATION - REAR DISC BRAKE ROTOR
(1) Install rotor on axle studs.
(2) Install the caliper anchor assembly.
(3) Install anchor bolts and tighten to 90-115 N´m
(66-85 ft. lbs.).
(4) Install wheel and tire assembly.
(5) Remove support and lower the vehicle.
(6) Pump brake pedal until caliper pistons and
brake shoes are seated.
PARKING BRAKE
OPERATION
The parking brakes operated by a automatic ten-
sioner mechanism built into the hand lever and cable
system. The front cable is connected to the hand
lever and the equalizer. The rear cables attached to
the equalizer and the parking brake shoe actuator.
A set of drum type brake shoes are used for park-
ing brakes. The shoes are mounted to the rear disc
brake adaptor. The parking brake drum is integrated
into the rear disc brake rotor.
Parking brake cable adjustment is controlled by an
automatic tensioner mechanism. The only adjust-
ment if necessary is to the park brake shoes if the
linings are worn.
DIAGNOSIS AND TESTING - PARKING BRAKE
NOTE: Parking brake adjustment is controlled by an
automatic cable tensioner and does not require
adjustment. The only adjustment that may be nec-
essary would be to the park brake shoes if they are
worn.
The parking brake switch is in circuit with the red
warning lamp in the dash. The switch will cause the
lamp to illuminate only when the parking brakes are
applied. If the lamp remains on after parking brake
release, the switch or wires are faulty.
If the red lamp comes on a fault has occurred in
the front or rear brake hydraulic system.
If the red warning lamp and yellow warning lamp
come on, the electronic brake distribution may be at
fault.
In most cases, the actual cause of an improperly
functioning parking brake (too loose/too tight/won't
hold), can be traced to a parking brake component.
NOTE: The leading cause of improper parking brake
operation, is excessive clearance between the park-
ing brake shoes and the shoe braking surface.
Excessive clearance is a result of lining and/or
drum wear, drum surface machined oversize.
Excessive parking brake lever travel (sometimes
described as a loose lever or too loose condition), is
the result of worn brake shoes, improper brake shoe
adjustment, or improperly assembled brake parts.
A too loose condition can also be caused by inoper-
ative or improperly assembled parking brake shoe
parts.
A condition where the parking brakes do not hold,
will most probably be due to a wheel brake compo-
nent.
Items to look for when diagnosing a parking brake
problem, are:
²Brake shoe wear
²Drum surface (in rear rotor) machined oversize
²Front cable not secured to lever
²Rear cable not attached to actuator
²Rear cable seized
²Parking brake lever not seated
²Parking brake lever bind
5 - 34 BRAKES - BASEWJ
ROTORS (Continued)

(7) Raise and support the vehicle.
(8) Remove the wheel and tire assemblies.
(9) Remove the brake calipers, caliper anchors and
rotors.
(10) Remove the ABS sensor wiring harness (Fig.
74)from the rear brake cables.
(11) Remove the cable retainer bolts (Fig. 74) from
the rear spring pads.
(12) Pull the cables out of the upper suspension
arm brackets.
(13) Push the cable in and lift up the end of cable
with a small screw driver to disengage the cable from
the parking brake actuator (Fig. 75).
(14) Remove the cable from the vehicle.
INSTALLATION
INSTALLATION - FRONT PARKING BRAKE
CABLE
(1) Install thecable into the parking brake lever
bracket and equalizer bracket.
(2) Install the front cable to the floor pan and
install retainer nuts.
(3) Engage the front cable ends to the parking
brake lever and equalizer.
(4) Install the front carpet, (Refer to 23 - BODY/
INTERIOR/CARPETS AND FLOOR MATS -
INSTALLATION).
(5) Pull on the lever to release the lock out spring.
(6) Install the center console, (Refer to 23 - BODY/
INTERIOR/FLOOR CONSOLE - INSTALLATION).
(7) Fold down the rear carpet cover and rear seat.
INSTALLATION - REAR PARKING BRAKE
CABLES
(1) Install the cables through the caliper anchor
mount. Then push the end of cable strand in to
engage the cable end to the parking brake actuator.
(2) Feed the other end of the cables through the
body and into the equalizer bracket (Fig. 76).
Fig. 74 Left Rear Parking Brake Cable
1 - CABLE BRACKET
2 - UPPER SUSPENSION ARM
3 - PARKING BRAKE CABLE
4 - CABLE RETAINER
5 - ABS SENSOR WIRING
Fig. 75 Parking Brake
1 - CABLE END
2 - SCREW DRIVER
3 - PARKING BRAKE ACTUATOR
4 - BRAKE SHOES
Fig. 76 Equalizer Bracket
1 - EQUALIZER
2 - RIGHT REAR CABLE
3 - LEFT REAR CABLE
4 - FRONT CABLE
WJBRAKES - BASE 5 - 37
CABLES (Continued)

(3) Push the cables into the upper suspension arm
brackets.
(4) Install the cable retainer bolts to the rear
spring pads.
(5) Install the ABS sensor wiring harness to the
rear brake cables.
(6) Install the rotors, caliper anchors and brake
calipers.
(7) Install the wheel and tire assemblies.
(8) Remove support and lower the vehicle.
(9) Engage the cable ends into the parking brake
equalizer.
(10) Pull on the lever to release the lock out
spring.
(11) Install center console, (Refer to 23 - BODY/IN-
TERIOR/FLOOR CONSOLE - INSTALLATION).
(12) Fold down the rear carpet cover and rear seat.
(13) Verify parking brake operation.
LEVER
REMOVAL
(1) Remove center console,(Refer to 23 - BODY/IN-
TERIOR/FLOOR CONSOLE - REMOVAL).
(2) Lift up rear seat and carpet covering the park-
ing brake cables.
(3) Place a screw driver through the front cable
eyelet (Fig. 77) and pry back on the front cable.(4) Have an assistant pry down the lock out spring
through the hole in the side of the park brake lever
(Fig. 78) with a small screw driver. Then slowly
release the front cable.
NOTE: Their should be slack in the cable if the lock
out spring is engaged.
(5) Disconnect parking brake switch wiring con-
nector.
(6) Disengage front cable end from parking brake
lever.
(7) Compress the cable retainer with a 13 mm
wrench (Fig. 79) and remove the cable from the park-
ing brake lever bracket.
Fig. 77 FRONT CABLE
1 - REAR CABLES
2 - FRONT CABLE EYELET
3 - FRONT CABLE
4 - EQUALIZER
Fig. 78 Lock Out Spring
1 - LOCK OUT SPRING
Fig. 79 Parking Brake Lever Bracket
1 - FRONT CABLE
2 - WRENCH
5 - 38 BRAKES - BASEWJ
CABLES (Continued)

(8) Remove the park brake lever mounting nuts
and console bracket (Fig. 80).
(9) Lift the lever assembly off the mounting studs
and pull the front cable out of the lever bracket.
INSTALLATION
(1) Install the lever assembly on the mounting
studs while feeding the front cable into the lever
bracket.
(2) Install the console bracket (Fig. 80) and mount-
ing nuts.
(3) Engage the front cable end to the lever.
(4) Connect parking brake switch wire connector.
(5) Pull on the lever to release the lock out spring.
(6) Install center console,(Refer to 23 - BODY/IN-
TERIOR/FLOOR CONSOLE - INSTALLATION).
(7) Fold down the rear carpet cover and rear seat.
SHOES
REMOVAL
(1) Lock out park brake lever (Fig. 81).
(2) Raise vehicle.
(3) Remove rear wheel and tire assembly.
(4) Remove caliper and anchor as an assembly.
(5) Remove rubber access plug from back of rear
disc brake splash shield.
(6) If necessary retract parking brake shoes with
brake adjuster tool (Fig. 82). Position tool at top of
star wheel and rotate wheel.
(7) Remove rotor from axle hub flange.
(8) Remove the lower shoe to shoe spring/adjuster
spring with needle nose pliers (Fig. 83).
(9) Remove the upper shoe to shoe spring/return
spring with brake pliers (Fig. 84).(10) Remove shoe hold-down clips and pins (Fig.
85). Clip is held in place by pin which fits in clip
notch. To remove clip, first push clip ends together
and slide clip until head of pin clears narrow part of
notch. Then remove clip and pin.
(11) Remove shoes and adjuster.
INSTALLATION
(1) Install shoes on splash shield with hold down
clips and pins. Be sure shoes are properly engaged in
the park brake actuator.
(2) Lubricate and install adjuster screw assembly.
Be sure notched ends of screw assembly are properly
seated on shoes and that star wheel is aligned with
access hole in shield.
Fig. 80 Parking Brake Lever Mounting
1 - MOUNTING NUT
2 - PARK BRAKE LEVER
Fig. 81 Lock Out Spring
1 - LOCK OUT SPRING
Fig. 82 Retracting Parking Brake Shoes
1 - ACCESS HOLE
2 - BRAKE ADJUSTING TOOL
3 - SPLASH SHIELD
WJBRAKES - BASE 5 - 39
LEVER (Continued)

ELECTRIC BRAKE
DESCRIPTION
The electronic brake distribution (EBD) functions
like a rear proportioning valve. The EBD system uses
the ABS system to control the slip of the rear wheels
in partial braking range. The braking force of the
rear wheels is controlled electronically by using the
inlet and outlet valves located in the HCU.
OPERATION
Upon entry into EBD the inlet valve for the rear
brake circuit is switched on so that the fluid supply
from the master cylinder is shut off. In order to
decrease the rear brake pressure the outlet valve for
the rear brake circuit is pulsed. This allows fluid to
enter the low pressure accumulator (LPA) in the
HCU resulting in a drop in fluid pressure to the rear
brakes. In order to increase the rear brake pressure
the outlet valve is switched off and the inlet valve is
pulsed. This increases the pressure to the rear
brakes. This will continue until the required slip dif-
ference is obtained. At the end of EBD braking (no
brake application) the fluid in the LPA drains back to
the master cylinder by switching on the outlet valve
and draining through the inlet valve check valve. At
the same time the inlet valve is switched on to pre-
vent a hydraulic short circiut in case of another
brake application.
The EBD will remain functional during many ABS
fault modes. If the red and amber warning lamps are
illuminated the EBD may have a fault.
FRONT WHEEL SPEED
SENSOR
DESCRIPTION
A wheel speed sensor is used at each wheel. The
front sensors are mounted to the steering knuckles.
The rear sensors are mounted at the outboard end of
the axle. Tone wheels are mounted to the outboard
ends of the front and rear axle shafts. The gear type
tone wheel serves as the trigger mechanism for each
sensor.
OPERATION
The sensors convert wheel speed into a small digi-
tal signal. The CAB sends 12 volts to the sensors.
The sensor has an internal magneto resistance
bridge that alters the voltage and amperage of the
signal circuit. This voltage and amperage is changed
by magnetic induction when the toothed tone wheel
passes the wheel speed sensor. This digital signal issent to the CAB. The CAB measures the voltage and
amperage of the digital signal for each wheel.
REMOVAL
(1) Raise and support the vehicle.
(2) Remove the front wheel sensor mounting bolt
(Fig. 1).
(3) Remove the sensor from the steering knuckle.
(4) Disengage the sensor wire from the brackets
(Fig. 1)on the steering knuckle.
(5) Disconnect the sensor from the sensor harness
(Fig. 2)and (Fig. 3).
(6) Remove the sensor and wire.
INSTALLATION
(1) Install the sensor on the steering knuckle.
(2) Apply Mopar Lock N' Seal or Loctitet242 to
the sensor mounting bolt. Use new sensor bolt if orig-
inal bolt is worn or damaged.
(3) Install the sensor mounting bolt and tighten
bolt to 12-14 N´m (106-124 in. lbs.).
(4) Engage the grommets on the sensor wire to the
steering knuckle brackets.
(5) Connect the sensor wire to the harness connec-
tor.
(6) Check the sensor wire routing. Be sure the
wire is clear of all chassis components and is not
twisted or kinked at any spot.
(7) Remove the support and lower vehicle.
Fig. 1 Sensor Location
1 - BRACKET
2 - BRACKET
3 - WHEEL SPEED SENSOR
4 - MOUNTING BOLT
WJBRAKES - ABS 5 - 43

(3) Connect the harness to the switch. Be sure the
harness connector is firmly seated.
(4) Place the carpet in position and fold the rear
seat back down.
REAR WHEEL SPEED SENSOR
DESCRIPTION
A wheel speed sensor is used at each wheel. The
front sensors are mounted to the steering knuckles.The rear sensors are mounted at the outboard end of
the axle. Tone wheels are mounted to the outboard
ends of the front and rear axle shafts. The gear type
tone wheel serves as the trigger mechanism for each
sensor.
OPERATION
The sensors convert wheel speed into a small digi-
tal signal. The CAB sends 12 volts to the sensors.
The sensor has an internal magneto resistance
bridge that alters the voltage and amperage of the
signal circuit. This voltage and amperage is changed
by magnetic induction when the toothed tone wheel
passes the wheel speed sensor. This digital signal is
sent to the CAB. The CAB measures the voltage and
amperage of the digital signal for each wheel.
REMOVAL
(1) Raise and fold the rear seat forward. Then
move the carpeting aside for access to the rear sensor
connectors.
(2) Disconnect the rear sensor wire at the harness
connectors (Fig. 7).
(3) Push the sensor wires and grommets through
the floorpan holes.
(4) Raise and support the vehicle.
(5) Disengage the sensor wire from the axle and
the chassis brackets and from the brake line retain-
ers.
(6) Remove the sensor mounting bolt from the rear
brake backing plate. (Fig. 8).
(7) Remove the sensor from the backing plate.
Fig. 5 G-Switch Mounting
1 - MOUNTING BOLTS
2 - CONNECTOR
3 - G-SWITCH
Fig. 6 G-Switch
1 - SWITCH PART NUMBER
2 - ARROW INDICATES FRONT OF SWITCH FOR PROPER
MOUNTING
Fig. 7 Rear Sensor Connector
1 - RIGHT REAR WHEEL SPEED SENSOR CONNECTOR
2 - LEFT REAR WHEEL SPEED SENSOR CONNECTOR
3 - G-SWITCH SENSOR
4 - PARKING BRAKE CABLES
WJBRAKES - ABS 5 - 45
G-SWITCH (Continued)