2002 JEEP LIBERTY Jb power

BRAKES
TABLE OF CONTENTS
page page
POWER BRAKE BOOSTER
REMOVAL - RHD........................1INSTALLATION - RHD.....................1
POWER BRAKE BOOSTER
REMOVAL - RHD
(1) Remove the air box (Refer to 9 - ENGINE/AIR
INTAKE SYSTEM/AIR CLEANER ELEMENT -
REMOVAL).
(2) Relocate the cruise control servo to gain access
to the booster for removal.
(3) Remove the brake lines from the master cylin-
der.
(4) Remove the master cylinder (Refer to 5 -
BRAKES/HYDRAULIC/MECHANICAL/MASTER
CYLINDER - REMOVAL).
(5) Disconnect vacuum hose from booster check
valve.
(6) Remove knee blocker under the steering colum-
n,(Refer to 23 - BODY/INSTRUMENT PANEL/KNEE
BLOCKER - REMOVAL).
(7) Remove the brake light switch.(Refer to 8 -
ELECTRICAL/LAMPS/LIGHTING - EXTERIOR/
BRAKE LAMP SWITCH - REMOVAL)
(8) Remove retaining clip that secures booster
push rod to brake pedal (Fig. 1).
(9) Remove nuts attaching booster to the dash
panel (Fig. 2).(10) In engine compartment, slide booster studs
out of dash panel, tilt booster upward, and remove
booster from engine compartment.
INSTALLATION - RHD
(1) Align and position booster on the dash panel.
(2) Install booster mounting nuts. Tighten nuts
just enough to hold booster in place.
(3) Slide booster push rod onto the brake pedal.
Then secure push rod to pedal pin with retaining
clip.
NOTE: Lubricate the pedal pin with Mopar multi-
mileage grease before installation.
(4) Tighten booster mounting nuts to 39 N´m (29
ft. lbs.).
(5) Install the brake light switch.
(6) Install the knee blocker,(Refer to 23 - BODY/
INSTRUMENT PANEL/KNEE BLOCKER - INSTAL-
LATION).
(7) If original master cylinder is being installed,
check condition of seal at rear of master cylinder.
Replace seal if cut, or torn.
(8) Clean cylinder mounting surface of brake
booster. Use shop towel wetted with brake cleaner for
Fig. 1 BOOSTER PUSH ROD
1 - BRAKE PEDAL
2 - BOOSTER ROD
Fig. 2 BOOSTER MOUNTING
1 - BRAKE BOOSTER
KJBRAKES 5s - 1

this purpose. Dirt, grease, or similar materials will
prevent proper cylinder seating and could result in
vacuum leak.
(9) Align and install master cylinder on the
booster studs. Install mounting nuts and tighten to
17.5 N´m (155 in. lbs.).
(10) Connect vacuum hose to booster check valve.
(11) Remount the cruise control servo to the origi-
nal location. Tighten bracket mounting nuts to 17.5
N´m (155 in. lbs.).(12) Connect and secure the brake lines to HCU
and master cylinder. Start all brake line fittings by
hand to avoid cross threading.
(13) Connect the wire to fluid reservoir.
(14) Install the air box.
(15) Fill and bleed base brake system,(Refer to 5 -
BRAKES - STANDARD PROCEDURE).
(16) Verify proper brake operation before moving
vehicle.
5s - 2 BRAKESKJ
POWER BRAKE BOOSTER (Continued)

(2) Lubricate input shaft splines, bearing retainer
slide surface, fork pivot and release fork pivot sur-
face.
(3) Install new release bearing. Be sure bearing is
properly secured to release fork.
(4) Install transmission.
FLYWHEEL
DESCRIPTION
STANDARD FLYWHEEL
The standard flywheel is used on the 3.7L engine.
The flywheel (Fig. 3) is a heavy plate bolted to the
rear of the crankshaft. The flywheel incorporates the
ring gear around the outer circumference to mesh
with the starter to permit engine cranking. The rear
face of the flywheel serves as the driving member to
the clutch disc.
DUAL MASS FLYWHEEL
The Dual Mass Flywheel is used on the 2.4 l
engine (Fig. 4). The flywheel incorporates the ring
gear around the outer circumference to mesh with
the starter to permit engine cranking. The primary
flywheel side is bolted to the crankshaft. The second-
ary flywheel face serves as the driving member to the
clutch disc. Internal springs between the flywheels
are use to dampen energy.
OPERATION
The flywheel serves to dampen the engine firing
pulses. The heavy weight of the flywheel relative to
the rotating mass of the engine components serves to
stabilize the flow of power to the remainder of the
drivetrain. The crankshaft has the tendency toattempt to speed up and slow down in response to
the cylinder firing pulses. The flywheel dampens
these impulses by absorbing energy when the crank-
shaft speeds and releasing the energy back into the
system when the crankshaft slows down.
Fig. 2 CLUTCH RELEASE BEARING
1 - RELEASE BEARING
2 - RELEASE FORK
Fig. 3 FLYWHEEL
1 - CRANKSHAFT
2 - RING GEAR
3 - FLYWHEEL
Fig. 4 DUAL MASS FLYWHEEL
1 - LOCATING STUD
2 - BEARING
3 - SECONDARY FLYWHEEL
4 - DAMPER SPRING
5 - RING GEAR
6 - PRIMARY FLYWHEEL
7 - FRICTION DISC
KJCLUTCH 6 - 7
CLUTCH RELEASE BEARING (Continued)

CLUTCH PEDAL
REMOVAL
(1) Remove steering column lower cover and knee
blocker for access.
(2) Disconnect clutch pedal position switch wires.
(3) Disengage captured bushing lock tabs attach-
ing clutch master cylinder actuator to pedal pivot.
(4) Remove nuts attaching pedal and bracket to
dash panel and upper cowl support (Fig. 8).
(5) Separate pedal assemble from vehicle.
INSTALLATION
(1) Place clutch pedal and bracket over studs on
dash panel and cowl support.
(2) Install nuts to attach pedal and bracket to
dash panel and upper cowl support. Tighten nuts to
39 N´m (29 ft. lbs.) torque
(3) Engage captured bushing and actuator on
brake pedal pivot.
(4) Connect clutch pedal position switch wires.
CLUTCH SWITCH OVERRIDE
RELAY
DESCRIPTION
The clutch pedal position switch override relay is
located in the Power Distribution Center (PDC).
Refer to PDC cover label for location within PDC.
OPERATION
Refer to Clutch Pedal Position Switch Operation
for information.
REMOVAL
The Clutch Switch Override Relay is located in the
Power Distribution Center (PDC) (Fig. 9). Refer to
label on PDC cover for relay location.
(1) Remove PDC cover.
(2) Remove relay from PDC.
(3) Check condition of relay terminals and PDC
connector terminals for damage or corrosion. Repair
if necessary before installing relay.
(4) Check for pin height (pin height should be the
same for all terminals within the PDC connector).
Repair if necessary before installing relay.
INSTALLATION
The Clutch Switch Override Relay is located in the
Power Distribution Center (PDC). Refer to label on
PDC cover for relay location.
(1) Install relay to PDC.
(2) Install cover to PDC.
Fig. 8 CLUTCH PEDAL
1 - CYLINDER
2 - ACTUATOR SHAFT
3 - ACTUATOR EYE
4 - PEDAL PIN
5 - CONNECTOR
Fig. 9 POWER DISTRIBUTION CENTER (PDC)
1 - BATTERY
2 - PDC
3 - PDC COVER
6 - 10 CLUTCHKJ

CLUTCH PEDAL POSITION
SWITCH
DESCRIPTION
The clutch pedal position switch is located under
the instrument panel. It is attached to the clutch
master cylinder push rod (Fig. 10). The wiring har-
ness connection for the switch is made in the engine
compartment (Fig. 10).
The clutch pedal position switch override relay is
located in the Power Distribution Center (PDC).
Refer to PDC cover label for location within PDC.
OPERATION
The clutch pedal position switch is used to prevent
starter motor engagement unless the clutch pedal is
depressed.
4WD Feature:The clutch pedal position switch
override relay will inhibit operation of the position
switch when the vehicle transfer case is in the four±
wheel±drive (4WD) low-range position (only). This
feature will allow operation of the starter motor,
without the need for depressing the clutch pedal, for
certain off-road applications. If any Diagnostic Trou-
ble Codes (DTC's) for either the override relay or
transfer case switch are stored, the override relay
feature will be inhibited.
An input from this switch is also used to either
shut down and/or prevent operation of the speed con-
trol system when the clutch pedal is depressed.
DIAGNOSIS AND TESTING - CLUTCH PEDAL
POSITION SWITCH
(1) Locate switch 2±wire electrical connector in
engine compartment (Fig. 10). Disconnect wiring at
this point.
(2) Check for switch continuity with an ohmmeter
while operating clutch pedal up and down. Continu-ity should be broken and reapplied each time pedal is
pressed.
(3) If continuity is not present, or is always
present at any pedal position, replace switch. Switch
is not serviced separately. Replace clutch master
cylinder.
Fig. 10 CLUTCH PEDAL POSITION SWITCH
1 - CLUTCH MASTER CYLINDER
2 - CLUTCH PEDAL POSITION SWITCH
3 - CLUTCH PEDAL PIN
4 - MASTER CYLINDER PUSHROD
5 - ELECTRICAL CONNECTION (IN ENGINE COMPARTMENT)
KJCLUTCH 6 - 11

The cooling system also provides a means of heat-
ing the passenger compartment and cooling the auto-
matic transmission fluid (if equipped). The cooling
system is pressurized and uses a centrifugal water
pump to circulate coolant throughout the system.
OPERATION - HOSE CLAMPS
The spring type hose clamp applies constant ten-
sion on a hose connection. To remove a spring type
hose clamp, only use constant tension clamp pliers
designed to compress the hose clamp.
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - ON-BOARD
DIAGNOSTICS (OBD)
COOLING SYSTEM RELATED DIAGNOSTICS
The powertrain control module (PCM) has been
programmed to monitor certain cooling system com-
ponents:
²If the engine has remained cool for too long a
period, such as with a stuck open thermostat, a Diag-
nostic Trouble Code (DTC) can be set.
²If an open or shorted condition has developed in
the relay circuit controlling the electric radiator fan,
a Diagnostic Trouble Code (DTC) can be set.
If the problem is sensed in a monitored circuit
often enough to indicated an actual problem, a DTC
is stored. The DTC will be stored in the PCM mem-
ory for eventual display to the service technician.
(Refer to 25 - EMISSIONS CONTROL - DESCRIP-
TION).
ACCESSING DIAGNOSTIC TROUBLE CODES
To read DTC's and to obtain cooling system data,
(Refer to 25 - EMISSIONS CONTROL - DESCRIP-
TION).
ERASING TROUBLE CODES
After the problem has been repaired, use the DRB
scan tool to erase a DTC. Refer to the appropriate
Powertrain Diagnostic Procedures service informa-
tion for operation of the DRB scan tool.
DIAGNOSIS AND TESTING - PRELIMINARY
CHECKS
ENGINE COOLING SYSTEM OVERHEATING
Establish what driving conditions caused the com-
plaint. Abnormal loads on the cooling system such as
the following may be the cause:
²PROLONGED IDLE
²VERY HIGH AMBIENT TEMPERATURE
²SLIGHT TAIL WIND AT IDLE
²SLOW TRAFFIC
²TRAFFIC JAMS
²HIGH SPEED
²STEEP GRADES
Driving techniques that avoid overheating are:
²Idle with A/C off when temperature gauge is at
end of normal range.
(1) TRAILER TOWING:
Consult Trailer Towing section of owners manual.
Do not exceed limits.
(2) RECENT SERVICE OR ACCIDENT REPAIR:
Determine if any recent service has been per-
formed on vehicle that may effect cooling system.
This may be:
²Engine adjustments (incorrect timing)
²Slipping engine accessory drive belt(s)
²Brakes (possibly dragging)
²Changed parts. Incorrect water pump, or pump
rotating in wrong direction due to belt not correctly
routed
²Reconditioned radiator or cooling system refill-
ing (possibly under filled or air trapped in system).
NOTE: If investigation reveals none of the previous
items as a cause for an engine overheating com-
plaint, refer to following Cooling System Diagnosis
charts.
These charts are to be used as a quick-reference
only. Refer to the group text for information.
Fig. 2 Spring Clamp Size Location
1 - SPRING CLAMP SIZE LOCATION
KJCOOLING 7 - 3
COOLING (Continued)

CAUTION: DO NOT LET TENSIONER ARM SNAP
BACK TO THE FREEARM POSITION, SEVERE DAM-
AGE MAY OCCUR TO THE TENSIONER.
Belt tension is not adjustable. Belt adjustment is
maintained by an automatic ( spring load ) belt ten-
sioner.
(1) Disconnect negative battery cable from battery.
(2) Rotate belt tensioner until it contacts its stop.
Remove belt, then slowly rotate the tensioner into
the freearm position. (Fig. 3).INSTALLATION - 3.7L ENGINE
NOTE: The belt routing schematics are published
from the latest information available at the time of
publication. If anything differs between these sche-
matics and the Belt Routing Label, use the sche-
matics on Belt Routing Label. This label is located
in the engine compartment.
Belt tension is not adjustable. Belt adjustment is
maintained by an automatic ( spring load ) belt ten-
sioner.
(1) Check condition of all pulleys.
CAUTION: When installing the serpentine accessory
drive belt, the belt MUST be routed correctly. If not,
the engine may overheat due to the water pump
rotating in the wrong direction (Fig. 3).
(2) Install new belt (Fig. 3). Route the belt around
all pulleys except the idler pulley. Rotate the ten-
sioner arm until it contacts its stop position. Route
the belt around the idler and slowly let the tensioner
rotate into the belt. Make sure the belt is seated onto
all pulleys.
(3) With the drive belt installed, inspect the belt
wear indicator (Fig. 4). On 3.7L Engines the gap
between the tang and the housing stop ( measure-
ment A ) must not exceed 24 mm (.94 inches).
Fig. 3 Belt Routing - 3.7L
1 - GENERATOR PULLEY
2 - ACCESSORY DRIVE BELT
3 - POWER STEERING PUMP PULLEY
4 - CRANKSHAFT PULLEY
5 - IDLER PULLEY
6 - TENSIONER
7 - A/C COMPRESSOR PULLEY
8 - WATER PUMP PULLEY
Fig. 4 Accessory Drive Belt Wear Indicator
1 - AUTOMATIC TENSIONER ASSEMBLY
7 - 18 ACCESSORY DRIVEKJ
DRIVE BELTS - 3.7L (Continued)

The ECT sensor is a two-wire Negative Thermal
Coefficient (NTC) sensor. Meaning, as engine coolant
temperature increases, resistance (voltage) in the
sensor decreases. As temperature decreases, resis-
tance (voltage) in the sensor increases.
OPERATION
At key-on, the Powertrain Control Module (PCM)
sends out a regulated 5 volt signal to the ECT sensor.
The PCM then monitors the signal as it passes
through the ECT sensor to the sensor ground (sensor
return).
When the engine is cold, the PCM will operate in
Open Loop cycle. It will demand slightly richer air-
fuel mixtures and higher idle speeds. This is done
until normal operating temperatures are reached.
The PCM uses inputs from the ECT sensor for the
following calculations:
²for engine coolant temperature gauge operation
through CCD or PCI (J1850) communications
²Injector pulse-width
²Spark-advance curves
²ASD relay shut-down times
²Idle Air Control (IAC) motor key-on steps
²Pulse-width prime-shot during cranking
²O2 sensor closed loop times
²Purge solenoid on/off times
²EGR solenoid on/off times (if equipped)
²Leak Detection Pump operation (if equipped)
²Radiator fan relay on/off times (if equipped)
²Target idle speed
REMOVAL
2.4L
The Engine Coolant Temperature (ECT) sensor is
installed into a water jacket at left front of cylinder
head (Fig. 1).
WARNING: HOT, PRESSURIZED COOLANT CAN
CAUSE INJURY BY SCALDING. COOLING SYSTEM
MUST BE PARTIALLY DRAINED BEFORE REMOV-
ING THE COOLANT TEMPERATURE SENSOR.
(1) Partially drain cooling system.
(2) Disconnect electrical connector from sensor.
(3) Remove sensor from cylinder head.
3.7L
The Engine Coolant Temperature (ECT) sensor is
installed into a water jacket at front of intake mani-
fold near rear of generator (Fig. 2).
WARNING: HOT, PRESSURIZED COOLANT CAN
CAUSE INJURY BY SCALDING. COOLING SYSTEM
MUST BE PARTIALLY DRAINED BEFORE REMOV-
ING THE COOLANT TEMPERATURE SENSOR.(1) Partially drain cooling system.
(2) Disconnect electrical connector from sensor.
(3) Remove sensor from intake manifold.
Fig. 1 ECT AND UPPER TIMING BELT COVER/
BOLTS-2.4L
1 - UPPER TIMING BELT COVER
2 - ELECTRICAL CONNECTOR (ECT)
3 - MOUNTING BOLTS (3)
Fig. 2 MAP SENSOR / ECT SENSOR - 3.7L
1 - MOUNTING SCREWS
2 - MAP SENSOR
3 - ECT SENSOR
7 - 20 ENGINEKJ
ENGINE COOLANT TEMPERATURE SENSOR (Continued)