2003 JEEP GRAND CHEROKEE lamp

(12) Install cover and tighten bolts in a criss-cross
pattern to 41 N´m (30 ft. lbs.).
(13) Refill the differential with Mopar Hypoid
Gear Lubricant or equivalent to bottom of the fill
plug hole.
(14) Install fill hole plug.
(15) Remove support and lower the vehicle.
DIFFERENTIAL - TRAC-LOK
DIAGNOSIS AND TESTING
The most common problem is a chatter noise when
turning corners. Before removing the unit for repair,
drain, flush and refill the axle with the specified
lubricant. A container of Mopar Trac-loktLubricant
(friction modifier) should be added after repair ser-
vice or during a lubricant change.
After changing the lubricant, drive the vehicle and
make 10 to 12 slow, figure-eight turns. This maneu-
ver will pump lubricant through the clutches. This
will correct the condition in most instances. If the
chatter persists, clutch damage could have occurred.
DIFFERENTIAL TEST
The differential can be tested without removing the
differential case by measuring rotating torque. Make
sure brakes are not dragging during this measure-
ment.
(1) Place blocks in front and rear of both front
wheels.
(2) Raise one rear wheel until it is completely off
the ground.
(3) Engine off, transmission in neutral, and park-
ing brake off.
(4) Remove wheel and bolt Special Tool 6790 or
equivalent tool to studs.
(5) Use torque wrench on special tool to rotate
wheel and read rotating torque (Fig. 56).
(6) If rotating torque is less than 41 N´m (56 ft.
lbs.) or more than 271 N´m (200 ft. lbs.) on either
wheel the unit should be serviced.
DISASSEMBLY
(1) Clamp side gear Holding Fixture 6965 in a vise
and position the differential case on the Holding Fix-
ture (Fig. 57).
(2) Remove ring gear if the ring gear is to be
replaced. The Trac-loktdifferential can be serviced
with the ring gear installed.
Fig. 56 ROTATING TORQUE TEST
1 - SPECIAL TOOL WITH BOLT IN CENTER HOLE
2 - TORQUE WRENCH
Fig. 57 DIFFERENTIAL CASE FIXTURE
1 - HOLDING FIXTURE
2 - VISE
3 - DIFFERENTIAL
WJREAR AXLE - 226RBA 3 - 119
DIFFERENTIAL (Continued)

BRAKES
TABLE OF CONTENTS
page page
BRAKES - BASE........................... 1BRAKES - ABS........................... 41
BRAKES - BASE
TABLE OF CONTENTS
page page
BRAKES - BASE
DESCRIPTION..........................2
DIAGNOSIS AND TESTING - BASE BRAKE
SYSTEM.............................2
STANDARD PROCEDURE
STANDARD PROCEDURE - MANUAL
BLEEDING............................5
STANDARD PROCEDURE - PRESSURE
BLEEDING............................5
SPECIFICATIONS
BRAKE COMPONENTS..................6
TORQUE CHART......................6
SPECIAL TOOLS
BASE BRAKES........................7
BRAKE FLUID LEVEL SWITCH
REMOVAL.............................7
INSTALLATION..........................7
RED BRAKE WARN INDICATOR SWITCH
DESCRIPTION..........................7
OPERATION............................7
DIAGNOSIS AND TESTING - RED BRAKE
WARNING LAMP.......................7
ADJUSTABLE PEDAL SWITCH
REMOVAL.............................8
INSTALLATION..........................8
BRAKE LINES
DESCRIPTION..........................8
DIAGNOSIS AND TESTING - BRAKE HOSES
AND LINES...........................8
STANDARD PROCEDURE
STANDARD PROCEDURE - DOUBLE
INVERTED FLARING....................9
STANDARD PROCEDURE - ISO FLARING . . . 9
BRAKE PADS / SHOES
DESCRIPTION
DESCRIPTION - FRONT DISC BRAKE
SHOES.............................10DESCRIPTION - REAR DISC BRAKE SHOES . 10
OPERATION
OPERATION - FRONT DISC BRAKE SHOES . 10
OPERATION - REAR DISC BRAKE SHOES . . 10
REMOVAL
REMOVAL- FRONT DISC BRAKE SHOES . . . 11
REMOVAL - REAR DISC BRAKE SHOES....12
INSTALLATION
INSTALLATION - FRONT DISC BRAKE
SHOES.............................13
INSTALLATION - REAR DISC BRAKE
SHOES.............................14
DISC BRAKE CALIPERS
REMOVAL
REMOVAL - FRONT DISC BRAKE CALIPER . 14
REMOVAL - REAR DISC BRAKE CALIPER . . 15
DISASSEMBLY
DISASSEMBLY - FRONT DISC BRAKE
CALIPER............................17
DISASSEMBLY - REAR DISC BRAKE
CALIPER............................18
CLEANING - DISC BRAKE CALIPER.........19
INSPECTION - DISC BRAKE CALIPER.......19
ASSEMBLY
ASSEMBLY - FRONT DISC BRAKE CALIPER . 20
ASSEMBLY - REAR DISC BRAKE CALIPER . 21
INSTALLATION
INSTALLATION - FRONT DISC BRAKE
CALIPER............................22
INSTALLATION - REAR DISC BRAKE
CALIPER............................22
FLUID
DIAGNOSIS AND TESTING - BRAKE FLUID
CONTAMINATION.....................22
SPECIFICATIONS
BRAKE FLUID........................23
FLUID RESERVOIR
REMOVAL.............................23
WJBRAKES 5 - 1

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)

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)

DISASSEMBLY
DISASSEMBLY - FRONT DISC BRAKE CALIPER
(1) Drain the brake fluid from caliper.
(2) C-clamp a block of wood over one piston (Fig.
27).
(3) Take another piece of wood and pad it with
one-inch thickness of shop towels. Place this piece in
the outboard shoe side of the caliper in front of the
other piston. This will cushion and protect caliper
piston during removal (Fig. 28).(4) To remove the caliper piston directshort
bursts of low pressure airwith a blow gun
through the caliper brake hose port. Use only enough
air pressure to ease the piston out.
CAUTION: Do not blow the piston out of the bore
with sustained air pressure. This could result in a
cracked piston.
WARNING: NEVER ATTEMPT TO CATCH THE PIS-
TON AS IT LEAVES THE BORE. THIS COULD
RESULT IN PERSONAL INJURY.
(5) Remove the C-clamp and block of wood from
the caliper and clamp it over the dust boot of the
first piston removed. This will seal the empty piston
bore.
(6) Move the padded piece of wood in front of the
other piston.
(7) Remove the second piston using the same pro-
cedure withshort bursts of low pressure air.
(8) Remove piston dust boots with a suitable pry
tool (Fig. 29)and discard.
Fig. 27 C-Clamp One Piston
1 - BLOCK OF WOOD
2 - C-CLAMP
3 - CALIPER
Fig. 28 Protect Caliper Piston
1 - CALIPER
2 - PADDED BLOCK OF WOOD
3 - C-CLAMP
Fig. 29 Piston Dust Boot Removal
1 - CALIPER
2 - PISTON DUST BOOT
WJBRAKES - BASE 5 - 17
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)

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)