2002 JEEP GRAND CHEROKEE light

shoe lining against the inner surface of the disc
brake rotor. At the same time, fluid pressure within
the piston bores forces the caliper to slide inward on
the slide pins. This action brings the outboard brake
shoe lining into contact with the outer surface of the
disc brake rotor.
Fluid pressure acting simultaneously on the pis-
tons and caliper to produces a strong clamping
action. When sufficient force is applied, friction will
stop the rotors from turning and bring the vehicle to
a stop.
Application and release of the brake pedal gener-
ates only a very slight movement of the caliper and
pistons. Upon release of the pedal, the caliper and
pistons return to a rest position. The brake shoes do
not retract an appreciable distance from the rotor. In
fact, clearance is usually at, or close to zero. The rea-
sons for this are to keep road debris from getting
between the rotor and lining and in wiping the rotor
surface clear each revolution.
The caliper piston seals control the amount of pis-
ton extension needed to compensate for normal lining
wear.
During brake application, the seals are deflected
outward by fluid pressure and piston movement (Fig.
8). When the brakes (and fluid pressure) are
released, the seals relax and retract the pistons.
The front outboard brake shoes have wear indica-
tors.
REMOVAL
REMOVAL- FRONT DISC BRAKE SHOES
(1) Raise and support vehicle.
(2) Remove wheel and tire assembly.(3) Drain small amount of fluid from master cylin-
der brake reservoir withcleansuction gun.
(4) Bottom caliper pistons into the caliper by pry-
ing the caliper over (Fig. 9).
(5) Remove the caliper support spring by prying
the spring out of the caliper (Fig. 10).
(6) Remove the caliper slide pin bushing caps and
remove the slide pins (Fig. 11).
(7) Remove caliper from the anchor.
Fig. 8 Lining Wear Compensation By Piston Seal
1 - PISTON
2 - CYLINDER BORE
3 - PISTON SEAL BRAKE PRESSURE OFF
4 - CALIPER HOUSING
5 - DUST BOOT
6 - PISTON SEAL BRAKE PRESSURE ON
Fig. 9 Bottoming Caliper Piston
1 - ROTOR
2 - CALIPER
Fig. 10 Caliper Support Spring
1 - SUPPORT SPRING
2 - CALIPER
WJBRAKES - BASE 5 - 11
BRAKE PADS / SHOES (Continued)

(4) Remove caliper piston dust boot with a suitable
pry tool (Fig. 34) and discard.
(5) Remove piston seal from the caliper (Fig.
35)and discard.
CAUTION: Do not scratch the piston bore while
removing the seal.
(6) Remove caliper slide pin bushings (Fig. 36).
(7) Remove caliper bleed screw.
CLEANING - DISC BRAKE CALIPER
Clean the caliper components with clean brake
fluid or brake clean only. Wipe the caliper and piston
dry with lint free towels or use low pressure com-
pressed air.
CAUTION: Do not use gasoline, kerosene, paint
thinner, or similar solvents. These products may
leave a residue that could damage the piston and
seal.
INSPECTION - DISC BRAKE CALIPER
The piston is made from a phenolic resin (plastic
material) and should be smooth and clean.
The piston must be replaced if cracked or scored.
Do not attempt to restore a scored piston surface by
sanding or polishing.
CAUTION: If the caliper piston is replaced, install
the same type of piston in the caliper. Never inter-
change phenolic resin and steel caliper pistons.
The pistons, seals, seal grooves, caliper bore and
piston tolerances are different.
The bore can belightlypolished with a brake
hone to remove very minor surface imperfections
(Fig. 37). The caliper should be replaced if the bore is
severely corroded, rusted, scored, or if polishing
would increase bore diameter more than 0.025 mm
(0.001 inch).
Fig. 34 Caliper Piston Dust
1 - PISTON DUST BOOT
2 - CALIPER
Fig. 35 Piston Seal Removal
1 - CALIPER
2 - PISTON BORE
3 - PISTON SEAL
Fig. 36 Slide Pin And Bushing
1 - BUSHING
2 - CALIPER SLIDE PIN
WJBRAKES - BASE 5 - 19
DISC BRAKE CALIPERS (Continued)

OPERATION
The master cylinder bore contains a primary and
secondary piston. The primary piston supplies
hydraulic pressure to the front brakes. The secondary
piston supplies hydraulic pressure to the rear brakes.
The master cylinder reservoir stores reserve brake
fluid for the hydraulic brake circuits.
DIAGNOSIS AND TESTING - MASTER
CYLINDER/POWER BOOSTER
NOTE: Inspect and repair any external fluid leaks
before performing test.
(1) Start engine and check booster vacuum hose
connections. A hissing noise indicates vacuum leak.
Correct any vacuum leak before proceeding.
(2)
Stop engine and shift transmission into Neutral.
(3) Pump brake pedal until all vacuum reserve in
booster is depleted.
(4) Press and hold brake pedal under light foot
pressure. The pedal should hold firm, if the pedal
falls away the master cylinder or HCU may be faulty
(internal leakage).
(5) Start engine and note pedal action. It should
fall away slightly under light foot pressure then hold
firm. If no pedal action is discernible, power booster,
vacuum supply, or vacuum check valve is faulty. Pro-
ceed to the POWER BOOSTER VACUUM TEST.
(6) If the POWER BOOSTER VACUUM TEST
passes, rebuild booster vacuum reserve as follows:
Release brake pedal. Increase engine speed to 1500
rpm, close the throttle and turn off the engine.
(7) Wait a minimum of 90 seconds and try brake
action again. Booster should provide two or more vac-
uum assisted pedal applications. If vacuum assist is
not provided, some component of the booster is faulty.
POWER BOOSTER VACUUM TEST
(1) Connect vacuum gauge to booster check valve
with short length of hose and T-fitting (Fig. 48).
(2) Start and run engine at curb idle speed for one
minute.
(3) Observe the vacuum supply. If vacuum supply
is not adequate, repair vacuum supply.
(4) Clamp hose shut between vacuum source and
check valve.
(5) Stop engine and observe vacuum gauge.
(6) If vacuum drops more than one inch HG (33
millibars) within 15 seconds, booster diaphragm,
check valve or check valve seal/grommet is faulty.
POWER BOOSTER CHECK VALVE TEST
(1) Disconnect vacuum hose from check valve.
(2)
Remove check valve and valve seal from booster.
(3) Use a hand operated vacuum pump for test.(4) Apply 51-67 kPa (15-20 in.) vacuum at large
end of check valve (Fig. 49).
(5) Vacuum should hold steady. If gauge on pump
indicates vacuum loss the check valve and seal
should be replaced.
Fig. 48 Typical Booster Vacuum Test Connections
1 - TEE FITTING
2 - SHORT CONNECTING HOSE
3 - CHECK VALVE
4 - CHECK VALVE HOSE
5 - CLAMP TOOL
6 - INTAKE MANIFOLD
7 - VACUUM GAUGE
Fig. 49 Vacuum Check Valve And Seal
1 - BOOSTER CHECK VALVE
2 - APPLY TEST VACUUM HERE
3 - VALVE SEAL
5 - 24 BRAKES - BASEWJ
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)

(2) Remove nut from pedal shaft.
(3) Slide pedal shaft out and remove brake pedal.
(4) Remove pedal bushings (Fig. 54) if they are to
be replaced.
REMOVAL - ADJUSTABLE PEDALS
NOTE: If possible put the pedals in the full forward
position.
(1) Disconnect the negative battery cable.
(2) Remove the cluster bezel (Refer to 23 - BODY/
INSTRUMENT PANEL/CLUSTER BEZEL - REMOV-
AL).
(3) Remove the steering column opening cover
(Refer to 23 - BODY/INSTRUMENT PANEL/STEER-
ING COLUMN OPENING COVER - REMOVAL).
(4) Disconnect the module electrical connector.
(5) Remove the brake light switch.
(6) Disconnect the booster rod clip (Fig. 53).
(7) Disconnect the accelerator cable from the
pedal.
(8) Lock the steering wheel into place.
(9) Remove the lower steering shaft pinch bolt
(Fig. 56).
(10) Separate the lower shaft coupler and push for-
ward (Fig. 56).
(11) Remove the two pedal bracket upper nuts
(Fig. 55).
(12) Remove the brake booster nuts (Fig. 56).
(13) Remove the accelerator pedal nuts (Fig. 57).(14) Remove the ICU mounting bracket nuts and
bolts and move the ICU and booster forward this will
allow enough clearance to remove the adjustable
pedal bracket from over the booster push rod.
(15) Remove the pedal from the vehicle (Fig. 56).
(16) Transfer the module if needed.
Fig. 54 Pedal Bushings
1 - BUSHING
2 - BUSHING
3 - SHAFT NUT
4 - PEDAL SHAFT
Fig. 55 UPPER MOUNTING NUTS
1 - UPPER MOUNTING STUDS
2 - ACCELERATOR MOUNTING STUDS
3 - UPPER MOUNTING NUT
4 - MOTOR
5 - ADJUSTABLE PEDAL BRACKET
Fig. 56 ADJUSTABLE PEDAL BRACKET
1 - BRAKE LIGHT SWITCH
2 - STEERING COLUMN
3 - ACCELERATOR PEDAL
4 - ADJUSTABLE PEDALS MOUNTING BRACKET
5 - BRAKE PEDAL
6 - MOTOR MOUNTING BRACKET
7 - BRAKE BOOSTER MOUNTING NUTS
(4)
WJBRAKES - BASE 5 - 27
PEDAL (Continued)

INSTALLATION
INSTALLATION - NON-ADJUSTABLE PEDAL
(1) Lubricate bushings, pedal shaft and pedal pin
with Mopar multi-mileage grease.
(2) Install bushings into pedal.
(3) Position pedal in bracket and install pedal
shaft in support and through pedal.
(4) Install new nut on pedal shaft and tighten to
27 N´m (20 ft. lbs.).
NOTE: Pedal shaft nut should not be reused.
(5) Install booster push rod on pedal pin and
install retainer clip on pedal pin.
(6) Check and adjust stop lamp switch if necessary.
INSTALLATION - ADJUSTABLE PEDALS
(1) Install the pedal to the vehicle (Fig. 56).
(2) Reposition the ICU and booster, Install the
ICU mounting bracket nuts and bolts.
28 N
(3) Install the brake booster nuts. Tighten to 28
N´m ( 21 ft. lbs.). (Fig. 56).
(4) Install the pedal bracket upper nuts. Tighten
to 12 N´m ( 9 ft. lbs.). (Fig. 56).
(5) Install the accelerator pedal nuts. Tighten to
28 N´m ( 21 ft. lbs.). (Fig. 57).
(6) Install the lower steering shaft coupler over the
shaft (Fig. 56).
(7) Install the lower steering shaft pinch bolt (Fig.
56).
(8) Unlock the steering wheel.
(9) Reconnect the accelerator cable to the pedal
(Fig. 56).(10) Reconnect the booster rod clip (Fig. 56).
(11) Install the brake light switch.
(12) Reconnect the module electrical connector.
(13) Install the steering column opening cover
(Refer to 23 - BODY/INSTRUMENT PANEL/STEER-
ING COLUMN OPENING COVER - INSTALLA-
TION).
(14) Install the cluster bezel (Refer to 23 - BODY/
INSTRUMENT PANEL/CLUSTER BEZEL -
INSTALLATION).
(15) Reconnect the negative battery cable.
PEDAL MOTOR
REMOVAL
(1) Disconnect the negative battery cable.
(2) Remove the cluster bezel (Refer to 23 - BODY/
INSTRUMENT PANEL/CLUSTER BEZEL - REMOV-
AL).
(3) Remove the steering column opening cover
(Refer to 23 - BODY/INSTRUMENT PANEL/STEER-
ING COLUMN OPENING COVER - REMOVAL).
(4) Remove the two mounting screws (Fig. 58).
(5) Disconnect the electrical connector (Fig. 58).
(6) Remove the adjustable pedal motor (Fig. 58).
INSTALLATION
(1) Install the adjustable pedal motor (Fig. 58).
(2) Reconnect the electrical connector (Fig. 58).
(3) Install the two mounting screws (Fig. 58).
(4) Install the steering column opening cover
(Refer to 23 - BODY/INSTRUMENT PANEL/STEER-
ING COLUMN OPENING COVER - INSTALLA-
TION).
Fig. 57 ACCELERATOR MOUNTING BRACKET
1 - ACCELERATOR MOUNTING NUTS
2 - ADJUSTABLE PEDALS BRACKET
3 - ACCELERATOR PEDAL
Fig. 58 ADJUSTABLE PEDALS MOTOR
1 - ELECTRICAL CONNECTOR
2 - PEDALS MOTOR
3 - MOUNTING SCREWS HOLES
5 - 28 BRAKES - BASEWJ
PEDAL (Continued)

REMOVAL
(1) Remove the master cylinder.
(2) Disconnect vacuum hose at booster check valve.
(3) Remove retainer clip (Fig. 60) that holds
booster push rod on pedal pin. Then slide push rod
off pin.
(4) Remove four nuts (Fig. 61) that attach booster
to dash panel.
(5) In engine compartment, slide booster forward,
tilt it upward slightly, and remove it from engine
compartment.
INSTALLATION
(1) Check condition of grommet that secures check
valve in booster. Replace grommet if cut, torn, or
loose.
(2) Install new booster dash seal.
(3) Align and position booster on engine compart-
ment side of dash panel.
(4) Inside passenger compartment:
(a) Lubricate pedal pin Mopar multi-mileage
grease.
(b) Install booster attaching nuts on studs.
Tighten attaching nuts to 39 N´m (29 ft. lbs.).
(c) Slide booster push rod on pedal pin. Then
secure rod to pin with retainer clip.
(5) In engine compartment, attach vacuum hose to
booster check valve.(6) Install the master cylinder with new gasket
and nuts.
CAUTION: The master cylinder installation proce-
dure must be perform as written or damage to the
booster/master cylinder may occur.
(7) Fill and bleed brake system.
ROTORS
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - FRONT DISC
BRAKE ROTOR
ROTOR MINIMUM THICKNESS
Rotor minimum usable thickness is 24.5 mm (0.964
in.). Do not resurface a rotor if machining would
cause thickness to fall below this limit.
Measure rotor thickness at the center of the brake
shoe contact surface. Replace the rotor if worn below
minimum thickness, or if refinishing would reduce
thickness below the allowable minimum.
FRONT ROTOR THICKNESS VARIATION
Variations in rotor thickness will cause pedal pul-
sation, noise and shudder.
Fig. 60 Retainer Clip
1 - RETAINER CLIP
2 - PUSH ROD
3 - PEDAL PIN
Fig. 61 Power Brake Booster Mounting
1 - BOOSTER
2 - DASH PANEL
WJBRAKES - BASE 5 - 31
POWER BRAKE BOOSTER (Continued)

(3) Install lower shoe to shoe spring/adjuster
spring. Needle nose pliers can be used to connect
spring to each shoe.
(4) Install the upper shoe to shoe spring/return
spring with brake pliers (Fig. 83).
(5) Install rotor and caliper anchor assembly.
(6) Install anchor bolts and tighten to 90-115 N´m
(66-85 ft. lbs.).
(7) Actuate park brake lever to unlock the park
brake system.
(8) Adjust the parking brake shoes (Fig. 82).
(9) Install wheel and tire assembly.
(10) Lower vehicle and verify correct parking
brake operation.
ADJUSTMENTS - PARKING BRAKE SHOE
(1) Remove wheel and tire assemblies.
(2) Secure rotor with two wheel nuts.
(3) Remove rubber access plug from back of splash
shield.
(4) Insert brake tool through access hole in splash
shield (Fig. 86). Position tool at bottom of star wheel.
(5) Rotate star wheel upward direction to expand
shoes (while facing front of vehicle).
(6) Expand shoes until light drag is experienced.
Then back off adjuster screw only enough to elimi-
nate drag.
(7) Install plug in splash shield access hole.
(8) Install wheel and tire assemblies.
Fig. 83 Lower Spring
1 - REAR SHOE
2 - NEEDLENOSE PLIERS
3 - ADJUSTER SCREW
4 - LOWER SPRING
Fig. 84 Upper Spring
1 - BRAKE PLIERS
2 - REAR SHOE
3 - UPPER SPRING
Fig. 85 Hold-Down Clip And Pin
1 - HOLD-DOWN CLIP
2 - HOLD-DOWN PIN
Fig. 86 Park Brake Shoe Adjustment
1 - ACCESS HOLE
2 - BRAKE ADJUSTING TOOL
3 - SPLASH SHIELD
5 - 40 BRAKES - BASEWJ
SHOES (Continued)