2003 JEEP GRAND CHEROKEE Brake pedal

BRAKE PADS / SHOES
DESCRIPTION
DESCRIPTION - FRONT DISC BRAKE SHOES
The calipers are twin piston type. The calipers are
free to slide laterally on the anchor, this allows con-
tinuous compensation for lining wear.
DESCRIPTION - REAR DISC BRAKE SHOES
The rear disc brakes consist of single piston float-
ing-type calipers and solid rotors. The rear caliper is
mounted on an anchor attached to an adapter
attached the rear axle tube flange. The anchors are
secured to the adapters with mounting bolts. The
disc brake rotor splash shield is part of the adaptor.
The disc brake rotor has a built in brake drum used
for the parking brakes (Fig. 6). The parking brake
shoes are mounted to the adaptor.
OPERATION
OPERATION - FRONT DISC BRAKE SHOES
When the brakes are applied fluid pressure is
exerted against the caliper pistons. The fluid pres-
sure is exerted equally and in all directions. This
means pressure exerted against the caliper pistons
and within the caliper bores will be equal (Fig. 7).
Fluid pressure applied to the pistons is transmit-
ted directly to the inboard brake shoe. This forces the
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.
OPERATION - REAR DISC BRAKE SHOES
When the brakes are applied fluid pressure is
exerted against the caliper pistons. The fluid pres-
sure is exerted equally and in all directions. This
means pressure exerted against the caliper pistons
and within the caliper bores will be equal (Fig. 7).
Fluid pressure applied to the pistons is transmit-
ted directly to the inboard brake shoe. This forces the
Fig. 6 Rear Disc Brake Rotor
1 - PARKING BRAKE DRUM SURFACE
2 - REAR DISC BRAKE ROTOR
Fig. 7 Brake Caliper Operation
1 - CALIPER
2 - PISTON
3 - PISTON BORE
4 - SEAL
5 - INBOARD SHOE
6 - OUTBOARD SHOE
5 - 10 BRAKES - BASEWJ

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)

(8) Install wheel and tire assembly.
(9) Remove support and lower vehicle.
(10) Pump brake pedal until caliper pistons and
brake shoes are seated and a firm brake pedal is
obtained.
(11) Fill brake fluid.
INSTALLATION - REAR DISC BRAKE SHOES
(1) Install the inboard brake shoe onto the caliper
(Fig. 17).
(2) Install the outboard brake shoe onto the caliper
anchor (Fig. 18).
(3) Lubricate the slide pins and slide pin bushings
with Dow Corningtgrease G807 or the grease pro-
vided with the brake shoes.
(4) Install caliper on the anchor.
(5) Install the caliper slide pin and tighten to
29-41 N´m (21-30 ft. lbs.).
(6) Install the caliper slide pin bushing caps.
(7) Install the caliper support spring in the top
end of the caliper and under the anchor. Then installother end into the lower caliper hole. Hold the spring
into the caliper hole with your thumb while prying
the end of the spring out and down under the anchor
with a screw drive.
(8) Install wheel and tire assembly.
(9) Remove support and lower vehicle.
(10) Pump brake pedal until caliper piston and
brake shoes are seated and a firm brake pedal is
obtained.
(11) Fill brake fluid level if necessary.
DISC BRAKE CALIPERS
REMOVAL
REMOVAL - FRONT DISC BRAKE CALIPER
(1) Raise and support vehicle.
(2) Remove front 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. 19).
Fig. 18 Outboard Brake Shoe
1 - OUTBOARD BRAKE SHOE
2 - CALIPER ANCHOR
3 - ROTOR
Fig. 19 Bottoming Caliper Piston
1 - ROTOR
2 - CALIPER
5 - 14 BRAKES - BASEWJ
BRAKE PADS / SHOES (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)

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)

(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)