Speed control system JEEP LIBERTY 2002 KJ / 1.G Workshop Manual

GROUP TAB LOCATOR
Introduction
0Lubrication & Maintenance
2Suspension
2SSuspension
3Differential & Driveline
5Brakes
5SBrakes
6Clutch
7Cooling
7SCooling
8AAudio
8BChime/Buzzer
8EElectronic Control Modules
8FEngine Systems
8GHeated Systems
8HHorn
8IIgnition Control
8JInstrument Cluster
8LLamps
8LSLamps
8MMessage Systems
8NPower Systems
8ORestraints
8PSpeed Control
8QVehicle Theft Security
8RWipers/Washers
8WWiring
9Engine
9SEngine
11Exhaust System
11SExhaust System
13Frame & Bumpers
14Fuel System
19Steering
21Transmission and Transfer Case
22Tires/Wheels
23Body
24Heating & Air Conditioning
25Emissions Control
Component and System Index
2.4L Gas Component and System Index
Service Manual Comment Forms
NOTE: For New Vehicle Preparation information, see the separate
publication, 81-170-00003.
NOTE: Group names with the suffix(S(indicate groups pertaining to the
the 2.4L Gas Supplement

VEHICLE EMISSION CONTROL
INFORMATION (VECI) LABEL
DESCRIPTION
All models have a Vehicle Emission Control Infor-
mation (VECI) Label. DaimlerChrysler permanently
attaches the label in the engine compartment (Fig.
4). The label cannot be removed without defacing
label information and destroying label.
The label contains the vehicle's emission specifica-
tions and vacuum hose routings. All hoses must be
connected and routed according to the label.
The label also contains an engine vacuum sche-
matic. There are unique labels for vehicles built for
sale in the state of California and the country of
Canada. Canadian labels are written in both the
English and French languages.
The VECI label contains the following:
²Engine family and displacement
²Evaporative family
²Emission control system schematic
²Certification application
²Engine timing specifications (if adjustable)
²Idle speeds (if adjustable)
²Spark plug and gap
VEHICLE IDENTIFICATION
NUMBER
DESCRIPTION
The Vehicle Identification Number (VIN) plate is
located on the lower left A-pillar and is visible
through the windshield (Fig. 5). The VIN contains 17
characters that provide data concerning the vehicle.
Refer to the VIN decoding chart to determine the
identification of a vehicle.
The Vehicle Identification Number is also
imprinted on the:
²Vehicle Safety Certification Label.
²Frame rail.
To protect the consumer from theft and possible
fraud the manufacturer is required to include a
Check Digit at the ninth position of the Vehicle Iden-
tification Number. The check digit is used by the
manufacturer and government agencies to verify the
authenticity of the vehicle and official documenta-
tion. The formula to use the check digit is not
released to the general public.
Fig. 4 VECI LABEL LOCATION
1 - RADIATOR SUPPORT
2 - VECI LABEL
Fig. 5 VIN NUMBER LOCATION
1 - A-PILLAR
2 - VIN CODE PLATE
8 INTRODUCTIONKJ

(4) Position the tube in the flaring tool flush with
the top of the tool bar (Fig. 3). Then tighten the tool
bar on the tube.
(5) Install the correct size adaptor on the flaring
tool yoke screw.
(6) Lubricate the adaptor.
(7) Align the adaptor and yoke screw over the tube
(Fig. 3).
(8) Turn the yoke screw in until the adaptor is
squarely seated on the tool bar.
REMOVAL
REMOVAL - FRONT HOSE
(1) Install prop rod on the brake pedal to keep
pressure on the brake system.
(2) Remove the brake line from the brake hose
inside the engine compartment by the front control
arm bolt (Fig. 4).
(3) Raise and support vehicle.
(4) Remove the brake hose banjo bolt at the cali-
per.
(5) Remove the mounting bolt for the top of the
brake hose at the vehicle (Fig. 5).
(6) Remove the hose.
REMOVAL - REAR BRAKE HOSE
(1) Install prop rod on the brake pedal to keep
pressure on the brake system.
(2) Raise and support the vehicle.
(3) Remove the brake line from the hose at the
body (Fig. 6).
(4) Remove the brake hose mounting bolt at the
top of the hose located at the body (Fig. 6).
(5) Remove the vent tube (Fig. 7).
(6) Remove the two brake lines at the bottom of
the hose located at the axle (Fig. 7).
(7) Remove the mounting bolt for the brake hose
at the axle (Fig. 7).
(8) Remove the hose.
Fig. 3 ISO Flaring
1 - ADAPTER
2 - LUBRICATE HERE
3 - PILOT
4 - FLUSH WITH BAR
5 - TUBING
6 - BAR ASSEMBLY
Fig. 4 INNER FENDER BRAKE LINE
1 - GROMMET
2 - BRAKE LINE
Fig. 5 FRONT BRAKE HOSE
1 - TOP OF FRONT BRAKE HOSE
2 - WHEEL SPEED SENSOR WIRE
3 - UPPER CONTROL ARM
KJBRAKES - BASE 5 - 9
BRAKE LINES (Continued)

INSTALLATION
INSTALLATION - FRONT BRAKE HOSE
(1) Install the hose.
(2) Install the mounting bolt for the top of the
brake hose at the vehicle (Fig. 8).(3) Install the brake hose banjo bolt at the caliper.
(4) Lower the vehicle and remove the support.
(5) Install the brake line to the brake hose inside
the engine compartment by the front control arm
bolt.
(6) Remove the prop rod from the brake pedal.
(7) Bleed the brake system (Refer to 5 - BRAKES -
STANDARD PROCEDURE).
INSTALLATION - REAR BRAKE HOSE
(1) Install the hose.
(2) Install the mounting bolt for the brake hose at
the axle (Fig. 7).
(3) Install the two brake lines at the bottom of the
hose located at the axle (Fig. 7).
(4) Install the vent tube (Fig. 7).
(5) Install the brake hose mounting bolt at the top
of the hose located at the body (Fig. 6).
(6) Install the brake line to the hose at the body
(Fig. 6).
(7) Lower the vehicle and remove the support.
(8) Remove the prop rod.
(9) Bleed the brake system (Refer to 5 - BRAKES -
STANDARD PROCEDURE).
BRAKE PADS / SHOES
DESCRIPTION - REAR DRUM BRAKE
The rear brakes use a leading shoe (primary) and
trailing shoe (secondary) design (Right rear brake is
shown) (Fig. 9).
Fig. 6 BRAKE HOSE AT THE BODY
1 - MOUNTING BOLT
2 - BRAKE HOSE
3 - BRAKE LINE
4 - COIL SPRING
Fig. 7 BRAKE HOSE AT THE AXLE
1 - REAR WHEEL SPEED SENSOR
2 - BRAKE HOSE
3 - VENT HOSE
4 - BRAKE LINES
5 - MOUNTING BOLT
Fig. 8 BRAKE HOSE MOUNTED
1 - COIL SPRING
2 - MOUNTING BOLT
3 - BRAKE HOSE
4 - FRONT OF THE UPPER CONTROL ARM
5 - 10 BRAKES - BASEKJ
BRAKE LINES (Continued)

BRAKES - ABS
TABLE OF CONTENTS
page page
BRAKES - ABS
DESCRIPTION.........................32
OPERATION...........................32
DIAGNOSIS AND TESTING - ANTILOCK
BRAKING SYSTEM....................33
STANDARD PROCEDURE - ABS BRAKE
BLEEDING...........................33
SPECIFICATIONS.......................33
ELECTRICAL
DESCRIPTION.........................34
OPERATION...........................34FRONT WHEEL SPEED SENSOR
REMOVAL.............................34
INSTALLATION.........................34
REAR WHEEL SPEED SENSOR
REMOVAL.............................35
INSTALLATION.........................35
HCU (HYDRAULIC CONTROL UNIT)
DESCRIPTION.........................35
OPERATION...........................35
REMOVAL.............................36
INSTALLATION.........................36
BRAKES - ABS
DESCRIPTION
ANTILOCK BRAKING SYSTEM
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 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 30
kph (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.
ELECTRONIC BRAKE DISTRIBUTION
The electronic brake distribution (EBD) functions
like a rear proportioning valve. The EBD system usesthe ABS system to control the slip of the rear wheels
in partial braking range. The braking force of the
rear wheels is controlled electronically by using the
inlet and outlet valves located in the HCU.
OPERATION
ANTILOCK BRAKING SYSTEM
During normal braking, the master cylinder, power
booster and wheel brake units all function as they
would in a vehicle without ABS. The HCU compo-
nents are not activated.
During antilock braking fluid pressure is modu-
lated according to wheel speed, degree of slip and
rate of deceleration. A sensor at each wheel converts
wheel speed into electrical signals. These signals are
transmitted to the CAB for processing and determi-
nation 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 control 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 sole-
noid valves are not static during antilock braking.
They are cycled continuously to modulate pressure.
Solenoid cycle time in antilock mode can be mea-
sured in milliseconds.
ELECTRONIC BRAKE DISTRIBUTION
Upon entry into EBD the inlet valve for the rear
brake circuit is switched on so that the fluid supply
from the master cylinder is shut off. In order to
decrease the rear brake pressure the outlet valve for
5 - 32 BRAKES - ABSKJ

the rear brake circuit is pulsed. This allows fluid to
enter the low pressure accumulator (LPA) in the
HCU resulting in a drop in fluid pressure to the rear
brakes. In order to increase the rear brake pressure
the outlet valve is switched off and the inlet valve is
pulsed. This increases the pressure to the rear
brakes. This will continue until the required slip dif-
ference is obtained. At the end of EBD braking (no
brake application) the fluid in the LPA drains back to
the master cylinder by switching on the outlet valve
and draining through the inlet valve check valve. At
the same time the inlet valve is switched on to pre-
vent a hydraulic short circiut in case of another
brake application.The EBD will remain functional
during many ABS fault modes. If the red and amber
warning lamps are illuminated the EBD may have a
fault.
DIAGNOSIS AND TESTING - ANTILOCK
BRAKING SYSTEM
The ABS brake system performs several self-tests
every time the ignition switch is turned on and the
vehicle is driven. The CAB monitors the systems
input and output circuits to verify the system is oper-
ating correctly. If the on board diagnostic system
senses that a circuit is malfunctioning the system
will set a trouble code in its memory.
NOTE: An audible noise may be heard during the
self-test. This noise should be considered normal.NOTE: The MDS or DRB III scan tool is used to
diagnose the ABS system. For additional informa-
tion refer to the Electrical, Electronic Control Mod-
ules section. For test procedures refer to the
Chassis Diagnostic Manual.
STANDARD PROCEDURE - ABS BRAKE
BLEEDING
ABS system bleeding requires conventional bleed-
ing methods plus use of the DRB scan tool. The pro-
cedure involves performing a base brake bleeding,
followed by use of the scan tool to cycle and bleed the
HCU pump and solenoids. A second base brake bleed-
ing procedure is then required to remove any air
remaining in the system.
(1) Perform base brake bleeding,(Refer to 5 -
BRAKES - STANDARD PROCEDURE) OR (Refer to
5 - BRAKES - STANDARD PROCEDURE).
(2) Connect scan tool to the Data Link Connector.
(3) Select ANTILOCK BRAKES, followed by MIS-
CELLANEOUS, then ABS BRAKES. Follow the
instructions displayed. When scan tool displays TEST
COMPLETE, disconnect scan tool and proceed.
(4) Perform base brake bleeding a second time,(Re-
fer to 5 - BRAKES - STANDARD PROCEDURE) OR
(Refer to 5 - BRAKES - STANDARD PROCEDURE).
(5) Top off master cylinder fluid level and verify
proper brake operation before moving vehicle.
SPECIFICATIONS
TORQUE SPECIFICATIONS
DESCRIPTION N´m Ft. Lbs. In. Lbs.
Hydraulic Control
Unit/Controller Antilock
Brakes Mounting Nuts14.1 Ð 125
Hydraulic Control
Unit/Controller Antilock
Brakes Brake Lines20.3 Ð 180
Controller Antilock Brakes
Mounting Screws1.8 Ð 16
Wheel Speed Sensors
Front Mounting Bolt12 Ð 132
Wheel Speed Sensor
Rear Mounting Bolt9Ð80
KJBRAKES - ABS 5 - 33
BRAKES - ABS (Continued)

REAR WHEEL SPEED SENSOR
REMOVAL
(1) Raise vehicle on hoist.
(2) Disconnect the sensor wire harness.
(3) Remove mounting stud from the sensor (Fig. 2).
(4) Remove sensor.
INSTALLATION
(1) Connect harness to sensor.Be sure seal is
securely in place between sensor and wiring
connector.
(2) Install O-ring on sensor (if removed).
(3) Insert sensor in differential housing.
(4) Install the sensor mounting stud and tighten to
9 N´m (80 in. lbs.).
(5) Install the sensor electical connector.
(6) Lower vehicle.
HCU (HYDRAULIC CONTROL
UNIT)
DESCRIPTION
The HCU consists of a valve body, pump motor,
and wire harness.
OPERATION
Accumulators in the valve body store extra fluid
released to the system for ABS mode operation. The
pump provides the fluid volume needed and is oper-
ated by a DC type motor. The motor is controlled by
the CAB.The valves modulate brake pressure during
antilock braking and are controlled by the CAB.
The HCU provides three channel pressure control
to the front and rear brakes. One channel controls
the rear wheel brakes in tandem. The two remaining
channels control the front wheel brakes individually.
During antilock braking, the solenoid valves are
opened and closed as needed. The valves are not
static. They are cycled rapidly and continuously to
modulate pressure and control wheel slip and decel-
eration.
During normal braking, the HCU solenoid valves
and pump are not activated. The master cylinder and
power booster operate the same as a vehicle without
an ABS brake system.
During antilock braking, solenoid valve pressure
modulation occurs in three stages, pressure increase,
pressure hold, and pressure decrease. The valves are
all contained in the valve body portion of the HCU.
PRESSURE DECREASE
The outlet valve is opened and the inlet valve is
closed during the pressure decrease cycle.
A pressure decrease cycle is initiated when speed
sensor signals indicate high wheel slip at one or
more wheels. At this point, the CAB closes the inlet
then opens the outlet valve, which also opens the
return circuit to the accumulators. Fluid pressure is
allowed to bleed off (decrease) as needed to prevent
wheel lock.
Once the period of high wheel slip has ended, the
CAB closes the outlet valve and begins a pressure
increase or hold cycle as needed.
PRESSURE HOLD
Both solenoid valves are closed in the pressure
hold cycle. Fluid apply pressure in the control chan-
nel is maintained at a constant rate. The CAB main-
tains the hold cycle until sensor inputs indicate a
pressure change is necessary.
PRESSURE INCREASE
The inlet valve is open and the outlet valve is
closed during the pressure increase cycle. The pres-
sure increase cycle is used to counteract unequal
wheel speeds. This cycle controls re-application of
fluid apply pressure due to changing road surfaces or
wheel speed.
Fig. 2 REAR WHEEL SPEED SENSOR
1 - DIFFERENTIAL HOUSING
2 - MOUNTING BOLT
3 - WHEEL SPEED SENSOR
KJBRAKES - ABS 5 - 35

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)

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)

RADIATOR FAN - ELECTRIC
DESCRIPTION
The fan (Fig. 12) is electrically controlled by the
powertrain control module (PCM) through the fan
control relay. This relay is located on the left wheel
house in the engine compartment.
OPERATION
The electric radiator cooling fan is controlled by
the Powertrain Control Module (PCM) through the
radiator cooling fan relay. The PCM regulates fan
operation based on input from the engine coolant
temperature sensor, battery temperature sensor,air
conditioning select switch and vehicle speed.
The fan is not energized during engine cranking
regardless of the electrical input from the tempera-
ture sensors and ,air conditioning switch. However, if
engine operation conditions warrant fan engagement,
the fan will run once engine starts.
On vehicles NOT equipped with AC:The relay
is energized when the coolant temperature is above
80É C (176É F), or battery temperature sensor above ±
12É C (10É F). It will then de-energize when coolant
temperature drops below 82É C (180É F), or batter
temperature sensor below ± 9É C ( 16É F).
Vehicles Equipped with AC:In addition to using
coolant temperature and battery temperature sensorto control cooling fan operation, the cooling fan will
also be engaged when the ,air conditioning system is
activated. The relay is also energized when, air con-
ditioning is selected and coolant temperature is
above 95É C ( 203É F), or , air conditioning is selected
and battery temperature sensor is above 41É C (106É
F). It will then de-energize when , air conditioning is
selected and coolant temperature is below 92É C
(198É F), or , air conditioning is selected and battery
temperature is below 38É C (100É F).
REMOVAL
If the fan blade is bent, warped, cracked or dam-
aged in any way, it must be replacedonlywith a
replacement fan blade.Do not attempt to repair a
damaged fan blade.
NOTE: For 3.7L Heavy Duty/Max Cool/Trailer Tow
cooling package, the vicous fan cannot be removed
seperate from the shroud. Both fan and shroud
must be removed together.
(1) Disconnect battery negative cable.
(2) Using special tool 6958 spanner wrench and
8346 adapters, remove the vicous fan from the water
pump (Fig. 13).
(3) Gently lay fan into shroud.
(4) Disconnect the electrical connector for the elec-
tric fan, then disconnect connector from shroud.
Fig. 12 Radiator Cooling Fan - Typical
1 - RADIATOR
2 - ELECTRIC COOLING FAN CONNECTOR
3 - FAN SHROUD
4 - ELECTRIC COOLING FAN
Fig. 13 Viscous Fan and Fan Drive 3.7L
1 - SPECIAL TOOL 6958 SPANNER WRENCH WITH ADAPTER
PINS 8346
2-FAN
7 - 26 ENGINEKJ