2002 JEEP GRAND CHEROKEE sensor

(3) Remove the wheels and tires.
(4) Remove brake calipers and rotors.
(5) Disconnect parking brake cables from brackets
and lever.
(6) Remove wheel speed sensors.
(7) Remove brake hose at the axle junction block.
Do not disconnect the brake hydraulic lines at the
calipers.
(8) Disconnect the vent hose from the axle shaft
tube.
(9) Mark propeller shaft and yokes for installation
reference.
(10) Remove propeller shaft.
(11) Disconnect stabilizer bar links.
(12) Remove upper suspension arm rear axle ball
joint nut.
(13) Separate rear axle ball joint from the upper
suspension arm with Remover 8278 (Fig. 4).
(14) Disconnect shock absorbers from axle.
(15) Disconnect track bar.
(16) Disconnect lower suspension arms from the
axle brackets.
(17) Separate the axle from the vehicle.
INSTALLATION
CAUTION: The weight of the vehicle must be sup-
ported by the springs before suspension arms and
track bar fasteners are tightened. If springs are notat their normal ride position, vehicle ride height and
handling could be affected.
(1) Raise axle with lift and align coil springs.
(2) Install lower suspension arms in axle brackets.
Install nuts and bolts, do not tighten bolts at this
time.
(3) Install upper suspension arm on rear axle ball
joint.
(4) Install rear axle ball joint nut and tighten to
122 N´m (90 ft.lbs.) (Fig. 5).
(5) Install track bar and attachment bolts, do not
tighten bolts at this time.
(6) Install shock absorbers and tighten nuts to 60
N´m (44 ft. lbs.).
(7) Install stabilizer bar links and tighten nuts to
36 N´m (27 ft. lbs.).
(8) Install wheel speed sensors.
(9) Connect parking brake cable to brackets and
lever.
(10) Install brake rotors and calipers.
(11) Install the brake hose to the axle junction
block.
(12) Install axle vent hose.
(13) Align propeller shaft and pinion yoke refer-
ence marks. Install U-joint straps and nuts tighten to
19 N´m (14 ft. lbs.).
(14) Install the wheels and tires.
(15) Add gear lubricant, if necessary.
(16) Remove support and lower the vehicle.
(17) Tighten lower suspension arm bolts to 177
N´m (130 ft. lbs.).
(18) Tighten track bar bolts to 100 N´m (74 ft.
lbs.).
Fig. 4 REAR BALL JOINT
1 - REMOVER
2 - UPPER SUSPENSION ARM
3 - BALL JOINT STUD
Fig. 5 REAR BALL JOINT NUT
1 - UPPER SUSPENSION ARM
2 - REAR AXLE BALL JOINT
3 - REAR AXLE
3 - 96 REAR AXLE - 226RBAWJ
REAR AXLE - 226RBA (Continued)

SPECIAL TOOLS
BASE BRAKESBRAKE FLUID LEVEL SWITCH
REMOVAL
(1) Remove the wire connector from the fluid level
sensor.
(2) From the same side of the master cylinder res-
ervoir release the sensor locking taps with a small
screw driver.
(3) Pull the sensor out of the reservoir from the
connector side of the sensor.
INSTALLATION
(1) Install the sensor with a new o-ring into the
reservoir until the locking tabs are engaged.
(2) Install the wire connector to the fluid level sen-
sor.
RED BRAKE WARN INDICATOR
SWITCH
DESCRIPTION
A red warning lamp is used for the service brake
portion of the hydraulic system. The lamp is located
in the instrument cluster.
OPERATION
The lamp is turned on momentarily when the igni-
tion switch is turn to the on position. This is a self
test to verify the lamp is operational.
The red warning light alerts the driver if the fluid
level is low or the parking brakes are applied. A red
warning lamp with an amber warning lamp may
indicate a electronic brake distribution fault.
DIAGNOSIS AND TESTING - RED BRAKE
WARNING LAMP
The red warning lamp illuminates when the park-
ing brake is applied or when the fluid level in the
master cylinder is low. It will also illuminate at start
up as part of a bulb check.
If the light comes on, first verify that the parking
brakes are fully released. Then check pedal action
and fluid level. If a problem is confirmed, inspect the
brake hydraulic system for leaks.
A red warning lamp with a amber warning lamp
may indicate a electronic brake distribution fault.
Installer Caliper Dust Boot 8280
Handle C-4171
Adapter Pressure Bleeder 6921
WJBRAKES - BASE 5 - 7
BRAKES - BASE (Continued)

rates into layers, there is mineral oil or other fluid
contamination of the brake fluid.
If brake fluid is contaminated, drain and thor-
oughly flush system. Replace master cylinder with
reservoir, caliper seals, HCU and all hydraulic fluid
hoses.
SPECIFICATIONS
BRAKE FLUID
The brake fluid used in this vehicle must conform
to DOT 3 specifications and SAE J1703 standards.
No other type of brake fluid is recommended or
approved for usage in the vehicle brake system. Use
only Mopar brake fluid or an equivalent from a
tightly sealed container.
CAUTION: Never use reclaimed brake fluid or fluid
from an container which has been left open. An
open container of brake fluid will absorb moisture
from the air and contaminate the fluid.
CAUTION: Never use any type of a petroleum-based
fluid in the brake hydraulic system. Use of such
type fluids will result in seal damage of the vehicle
brake hydraulic system causing a failure of the
vehicle brake system. Petroleum based fluids would
be items such as engine oil, transmission fluid,
power steering fluid, etc.
FLUID RESERVOIR
REMOVAL
(1) Remove reservoir cap and remove fluid with a
cleansuction gun.
(2) Remove the wire connector from the brake fluid
level sensor.
(3) Insert the tool (Fig. 47) provided with the res-
ervoir to release the reservoir retaining tabs.
(4) Pull the reservoir straight up out of the cylin-
der.
(5) Remove and discard grommets from the cylin-
der body.
INSTALLATION
(1) Lubricate new grommets with clean brake
fluid. Install new grommets into the cylinder body.
CAUTION: Do not use tools to install the grommets.
Tools may cut, or tear the grommets. Install the
grommets using finger pressure only.(2) Start reservoir in grommets then press the res-
ervoir straight down to seat the reservoir into the
cylinder grommets.
CAUTION: Do not rock the reservoir during installa-
tion.
(3) Verify retaining tabs are seated.
(4) Install the wire connector to the brake fluid
level sensor.
(5) Fill master cylinder.
MASTER CYLINDER
DESCRIPTION
The master cylinder body is made of aluminum
and contains a primary and secondary piston assem-
bly. The cylinder body including the piston assem-
blies are not serviceable. If diagnosis indicates an
internal problem with the cylinder body, it must be
replaced as an assembly. The master cylinder has a
removable reservoir and fluid level indicator. The res-
ervoir, reservoir grommets, reservoir cap and fluid
level switch are the only replaceable parts on the
master cylinder.
Fig. 47 Release Tool
1 - RESERVOIR
2 - RELEASE TOOL
3 - RETAINING TABS
WJBRAKES - BASE 5 - 23
FLUID (Continued)

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)

tions also allows the driver to set steering wheel tilt
and seat position to the most comfortable position.
The position of the brake and accelerator pedals can
be adjusted without compromising safety or comfort
in actuating the pedals. Repositioning the pedals
does not change the effort required for actuation.
Change of pedal position is accomplished by means
of a motor driven screw. Operating the adjustable
pedal switch activates the pedal drive motor. The
pedal drive motor turns a screw that changes the
position of the brake and accelerator pedals. The
pedal can be moved rearward (closer to the driver) or
forward (away from driver). The brake pedal is
moved on its drive screw to a position where the
driver feels most comfortable (Fig. 52).
The accelerator pedal is moved at the same time
and the same distance as the brake pedal. The accel-
erator pedal adjustment screw is turned by a flexible
shaft slaved off the brake adjustment screw.
Neither the pedal drive motor nor drive mecha-
nism are subject to the mechanical stress of brake or
accelerator application.
²SYSTEM FEATURES:
²Range of Adjustment: The pedals may be
adjusted up to 3 in. (75 mm)
²Pedal Adjustment Speed: 0.5 in./sec (12.5
mm/sec)
²Pedal Adjustment Inhibitors: Pedal adjust-
ment is inhibited when the vehicle is in reverse or
when cruise control is activated.
²Memory: An optional memory feature is avail-
able. This allows storing of one or two preferred
pedal positions in the Adjustable Pedal Module
(APM). A preferred position can be stored and
recalled using the door-mounted switches. A stored
pedal position can be recalled (but not stored)
using the Remote Keyless Entry (RKE).
²
Adjustable Pedal Feedback Message: The Elec-
tronic Vehicle Information Center (EVIC) will display
a message when the APS is disabled. ie:9Adjustable
Pedal Disabled - Cruise Control Engaged9or9Adjust-
able Pedal Disabled - Vehicle in Reverse9.
²Damage Prevention: Foot pressure or debris
can stall pedal adjustment. In order to avoid dam-
age to system components during pedal adjust-
ment, the APM will monitor pedal position sensor
voltage. If the APM does not detect expected volt-
age change within 1.5 seconds, it will cut power to
the adjustable pedal motor.
OPERATION
The brake pedal is attached to the booster push
rod. When the pedal is depressed, the primary
booster push rod is depressed which moves the
booster secondary rod. The booster secondary rod
depresses the master cylinder piston.
REMOVAL
REMOVAL - NON-ADJUSTABLE PEDAL
(1) Remove retainer clip that holds booster to
pedal pin (Fig. 53).
Fig. 52 ADJUSTABLE PEDALS ASSEMBLY
1 - HARNESS
2 - ADJUSTABLE PEDAL BRACKET
3 - CABLE
4 - ACCELERATOR PEDAL
5 - BRAKE PEDAL
6 - ADJUSTABLE PEDAL MOTOR
7 - BRAKE LIGHT SWITCH
8 - ADJUSTABLE PEDALS MODULE
Fig. 53 Push Rod Retainer Clip
1 - RETAINER CLIP
2 - PUSH ROD
3 - PEDAL PIN
5 - 26 BRAKES - BASEWJ
PEDAL (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)

BRAKES - ABS
TABLE OF CONTENTS
page page
BRAKES - ABS
DESCRIPTION.........................41
OPERATION...........................41
DIAGNOSIS AND TESTING - ANTILOCK
BRAKES............................42
STANDARD PROCEDURE - BLEEDING ABS
BRAKE SYSTEM......................42
SPECIFICATIONS
TORQUE CHART......................42
ELECTRIC BRAKE
DESCRIPTION.........................43
OPERATION...........................43
FRONT WHEEL SPEED SENSOR
DESCRIPTION.........................43
OPERATION...........................43
REMOVAL.............................43INSTALLATION.........................43
G-SWITCH
DESCRIPTION.........................44
OPERATION...........................44
REMOVAL.............................44
INSTALLATION.........................44
REAR WHEEL SPEED SENSOR
DESCRIPTION.........................45
OPERATION...........................45
REMOVAL.............................45
INSTALLATION.........................46
HCU (HYDRAULIC CONTROL UNIT)
DESCRIPTION.........................46
OPERATION...........................46
REMOVAL.............................47
INSTALLATION.........................47
BRAKES - ABS
DESCRIPTION
The purpose of the antilock system is to prevent
wheel lockup during periods of high wheel slip. Pre-
venting lockup helps maintain vehicle braking action
and steering control.
The hydraulic system is a three channel design.
The front brakes are controlled individually and the
rear brakes in tandem.
The ABS electrical system is separate from other
vehicle electrical circuits. A separate controller oper-
ates the system.
OPERATION
The antilock CAB activates the system whenever
sensor signals indicate periods of high wheel slip.
High wheel slip can be described as the point where
wheel rotation begins approaching 20 to 30 percent of
actual vehicle speed during braking. Periods of high
wheel slip occur when brake stops involve high pedal
pressure and rate of vehicle deceleration.
Battery voltage is supplied to the CAB ignition ter-
minal when the ignition switch is turned to Run posi-
tion. The CAB 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 30kph (18 mph). During the dynamic check, the CAB
briefly cycles the pump and solenoids to verify oper-
ation.
If an ABS component exhibits a fault during ini-
tialization, the CAB illuminates the amber warning
light and registers a fault code in the microprocessor
memory.
ANTILOCK BRAKING
The antilock system prevents lockup during high
slip conditions by modulating fluid apply pressure to
the wheel brake units.
Brake fluid apply pressure is modulated according
to wheel speed, degree of slip and rate of decelera-
tion. A sensor at each wheel converts wheel speed
into electrical signals. These signals are transmitted
to the CAB for processing and determination of
wheel slip and deceleration rate.
The ABS system has three fluid pressure control
channels. The front brakes are controlled separately
and the rear brakes in tandem. A speed sensor input
signal indicating a high slip condition activates the
CAB antilock program.
Two solenoid valves are used in each antilock con-
trol channel. The valves are all located within the
HCU valve body and work in pairs to either increase,
hold, or decrease apply pressure as needed in the
individual control channels.
The solenoid valves are not static during antilock
braking. They are cycled continuously to modulate
pressure. Solenoid cycle time in antilock mode can be
measured in milliseconds.
WJBRAKES - ABS 5 - 41