2002 JEEP LIBERTY relay

OPERATION
OPERATION - COOLING SYSTEM
The cooling system regulates engine operating tem-
perature. It allows the engine to reach normal oper-
ating temperature as quickly as possible. It also
maintains normal operating temperature and pre-
vents overheating.
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.
DIAGNOSIS AND TESTING - COOLING SYSTEM
LEAKS
ULTRAVIOLET LIGHT METHOD
A leak detection additive is available through the
parts department that can be added to cooling sys-
tem. The additive is highly visible under ultraviolet
light (black light). Pour one ounce of additive into
cooling system. Place heater control unit in HEAT
position. Start and operate engine until radiator
upper hose is warm to touch. Aim the commercially
available black light tool at components to be
checked. If leaks are present, black light will cause
additive to glow a bright green color.
7s - 2 COOLING - 2.4LKJ
COOLING - 2.4L (Continued)

DIAGNOSIS AND TESTING - COOLING SYSTEM
DIAGNOSIS CHART
COOLING SYSTEM DIAGNOSIS CHART
CONDITION POSSIBLE CAUSES CORRECTION
TEMPERATURE GAUGE READS
LOW1. Has a Diagnostic Trouble Code
(DTC) been set indicating a stuck
open thermostat?1. Refer to (Refer to 25 -
EMISSIONS CONTROL -
DESCRIPTION) for On-Board
Diagnostics and DTC information.
Replace thermostat if necessary.
2. Is the temperature sending unit
connected?2. Check the temperature sensor
connector. (Refer to 7 - COOLING/
ENGINE/ENGINE COOLANT TEMP
SENSOR - DESCRIPTION). Repair
connector if necessary.
3. Is the temperature gauge
operating OK?3. Check gauge operation. Repair
as necessary.
4. Coolant level low in cold ambient
temperatures accompanied with
poor heater performance.4. Check coolant level in the coolant
pressure botttle and the radiator.
Inspect system for leaks. Repair
leaks as necessary.
5. Improper operation of internal
heater doors or heater controls.5. Inspect heater and repair as
necessary. (Refer to 24 - HEATING
& AIR CONDITIONING -
DIAGNOSIS AND TESTING)
6. Electric fan functioning when not
required.6. Inspect electric fan for proper
operation. Refer to Electric Cooling
Fan in this section. Refer to group
8W for electric cooling fan and relay
circuit schematic data.
KJCOOLING - 2.4L7s-5
COOLING - 2.4L (Continued)

CONDITION POSSIBLE CAUSES CORRECTION
8. Incorrect coolant concentration 8. Check coolant. (Refer to 7 -
COOLING/ENGINE/COOLANT -
DESCRIPTION) for correct
coolant/water mixture ratio.
9. Fan installed backwards on
viscous drive.9. Mount fan on drive correctly.
10. Radiator or A/C condenser fins
are dirty or clogged.10. Remove insects and debris.
(Refer to 7 - COOLING/ENGINE/
RADIATOR - CLEANING).
11. Radiator core is corroded or
plugged.11. Have radiator re-cored or
replaced.
12. Fuel or ignition system
problems.12. Refer to FUEL and /or
IGNITION CONTROL for diagnosis.
13. Dragging brakes. 13. Check and correct as
necessary. (Refer to 5 - BRAKES -
DIAGNOSIS AND TESTING) for
correct procedures.
14. Bug screen or cardboard is
being used, reducing airflow.14. Remove bug screen or
cardboard.
15. Thermostat partially or
completely shut.15. Check thermostat operation and
replaces necessary. (Refer to 7 -
COOLING/ENGINE/ENGINE
COOLANT THERMOSTAT -
DIAGNOSIS AND TESTING).
16. Viscous fan drive not operating
properly.16. Check fan drive operation and
replace as necessary. (Refer to 7 -
COOLING/ENGINE/FAN DRIVE
VISCOUS CLUTCH - DIAGNOSIS
AND TESTING).
17. Cylinder head gasket leaking. 17. Check for cylinder head gasket
leaks. (Refer to 7 - COOLING -
DIAGNOSIS AND TESTING). For
repair, (Refer to 9 - ENGINE/
CYLINDER HEAD - REMOVAL).
18. Heater core leaking. 18. Check heater core for leaks.
(Refer to 24 - HEATING & AIR
CONDITIONING/PLUMBING/
HEATER CORE - REMOVAL).
Repair as necessary.
19. Electric fan not functioning. 19. Inspect electric fan for proper
operation. Refer to Electric Cooling
Fan in this section. Refer to Group
8W for electric cooling fan and relay
circuit schematic data.
KJCOOLING - 2.4L7s-7
COOLING - 2.4L (Continued)

ENGINE COOLANT
TEMPERATURE SENSOR
DESCRIPTION
The Engine Coolant Temperature (ECT) sensor is
used to sense engine coolant temperature. The sensor
protrudes into an engine water jacket.
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-width²Spark-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. 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 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. 3).
Fig. 1 ENGINE BLOCK HEATER 2.4L
1 - CORE HOLE
2 - BLOCK HEATER
3 - POWER CORD
Fig. 2 ECT AND UPPER TIMING BELT COVER/
BOLTS-2.4L
1 - UPPER TIMING BELT COVER
2 - ELECTRICAL CONNECTOR (ECT)
3 - MOUNTING BOLTS (3)
KJENGINE7s-21
ENGINE BLOCK HEATER - 2.4L (Continued)

RADIATOR FAN - ELECTRIC
DESCRIPTION
The fan (Fig. 11) 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 viscous 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 viscous fan from the
water pump (Fig. 12).
(3) Gently lay fan into shroud.
(4) Disconnect the electrical connector for the elec-
tric fan, then disconnect connector from shroud.
Fig. 11 Radiator Cooling Fan - Typical
1 - RADIATOR
2 - ELECTRIC COOLING FAN CONNECTOR
3 - FAN SHROUD
4 - ELECTRIC COOLING FAN
Fig. 12 Viscous Fan and Fan Drive 3.7L
1 - SPECIAL TOOL 6958 SPANNER WRENCH WITH ADAPTER
PINS 8346
2-FAN
7s - 26 ENGINEKJ

AUDIO
TABLE OF CONTENTS
page page
AUDIO
DESCRIPTION..........................1
OPERATION............................1
DIAGNOSIS AND TESTING - AUDIO..........2
AMPLIFIER CHOKE AND RELAY
DESCRIPTION..........................3
OPERATION............................3
DIAGNOSIS AND TESTING - AMPLIFIER
CHOKE AND RELAY....................4
REMOVAL.............................4
INSTALLATION..........................4
ANTENNA BODY & CABLE
DESCRIPTION..........................4
OPERATION............................5
DIAGNOSIS AND TESTING - ANTENNA BODY
AND CABLE..........................5
REMOVAL.............................6
INSTALLATION..........................6
CD CHANGER
DESCRIPTION..........................7
OPERATION............................7
REMOVAL.............................7
INSTALLATION..........................7
INSTRUMENT PANEL ANTENNA CABLE
REMOVAL.............................7INSTALLATION..........................8
RADIO
DESCRIPTION..........................8
OPERATION............................8
REMOVAL.............................9
INSTALLATION..........................9
RADIO NOISE SUPPRESSION GROUND STRAP
DESCRIPTION..........................9
OPERATION...........................10
REMOVAL.............................10
INSTALLATION.........................11
REMOTE SWITCHES
DESCRIPTION.........................11
OPERATION...........................12
DIAGNOSIS AND TESTING - REMOTE
SWITCHES..........................12
REMOVAL.............................13
INSTALLATION.........................13
SPEAKER
DESCRIPTION.........................13
OPERATION...........................14
REMOVAL.............................14
INSTALLATION.........................15
AUDIO
DESCRIPTION
An audio system is standard factory-installed
equipment on this model. Several combinations of
radio receivers and speaker systems are offered on
this model. The audio system uses an ignition
switched source of battery current so that the system
will only operate when the ignition switch is in the
RUN or ACCESSORY positions.
The audio system includes the following compo-
nents:
²Amplifier choke and relay
²Antenna
²Compact disc changer (if equipped)
²Power amplifier mounted to each front door
speaker (with premium speaker system only)
²Radio noise suppression components
²Radio receiver
²Remote radio switches (if equipped)
²SpeakersCertain functions and features of the audio system
rely upon resources shared with other electronic
modules in the vehicle over the Programmable Com-
munication Interface (PCI) bus network. The data
bus network allows the sharing of sensor informa-
tion. For diagnosis of these electronic modules or of
the data bus network, the use of a DRB scan tool and
the proper Diagnostic Procedures manual are recom-
mended.
Refer to the appropriate wiring information for
complete standard and premium audio system circuit
diagrams. The wiring information includes proper
wire and connector repair procedures, further details
on wire harness routing and retention, as well as
pin-out and location views for the various wire har-
ness connectors, splices, and grounds.
OPERATION
The audio system components are designed to pro-
vide audio entertainment and information through
the reception, tuning and amplification of locally
broadcast radio signals in both the Amplitude Modu-
KJAUDIO 8A - 1

CONDITION POSSIBLE CAUSES CORRECTION
5. Radio faulty. 5. Refer to appropriate Diagnostic Service
Manual.
CLOCK WILL NOT KEEP
SET TIME1. Fuse faulty. 1. Check Ignition-Off Draw (IOD) fuse in the
Junction Block (JB). Replace fuse, if required.
2. Radio connector faulty. 2. Check for loose or corroded radio connector.
Repair, if required.
3. Wiring faulty. 3. Check for battery voltage at radio connector.
Repair wiring, if required.
4. Radio ground faulty. 4. Check for continuity between radio chassis and
a known good ground. There should be
continuity. Repair ground, if required.
5. Radio faulty. 5. Refer to appropriate Diagnostic Service
Manual.
POOR RADIO RECEPTION 1. Antenna faulty. 1. (Refer to 8 - ELECTRICAL/AUDIO/ANTENNA
BODY & CABLE - DIAGNOSIS AND TESTING).
2. Radio ground faulty. 2. Check for continuity between radio chassis and
a known good ground. There should be
continuity. Repair ground, if required.
3. Radio noise suppression
faulty.3. Repair or replace ground strap as necessary.
4. Radio faulty. 4. Refer to appropriate Diagnostic Service
Manual.
NO/POOR TAPE
OPERATION1. Faulty tape. 1. Insert known good tape and test operation.
2. Foreign objects behind
tape door.2. Remove foreign objects and test operation.
3. Dirty cassette tape head. 3. Clean head with Mopar Cassette Head
Cleaner.
4. Faulty tape deck. 4. Exchange or replace radio, if required.
NO COMPACT DISC
OPERATION1. Faulty CD. 1. Insert known good CD and test operation.
2. Foreign material on CD. 2. Clean CD and test operation.
3. Condensation on CD or
optics.3. Allow temperature of vehicle interior to stabilize
and test operation.
4. Faulty CD player. 4. Refer to appropriate Diagnostic Service
Manual.
AMPLIFIER CHOKE AND
RELAY
DESCRIPTION
Models equipped with the premium speaker pack-
age have a amplifier choke and relay. The amplifier
choke and relay is mounted to the lower instrument
panel above the accelerator pedal.
The amplifier choke and relay should be checked if
there is no sound output from the speakers. The
amplifier choke and relay can not be repaired or
adjusted and, if faulty or damaged, the unit must be
replaced.
OPERATION
The amplifier choke and relay is used to control
the supply of fused battery current to the front door
speaker-mounted dual amplifiers. The speaker relay
is energized by a fused 12 volt output from the radio
receiver whenever the radio is turned on. For com-
plete circuit diagrams, refer to the appropriate wir-
ing information. The wiring information includes
wiring diagrams, proper wire and connector repair
procedures, details of wire harness routing and
retention, connector pin-out information and location
views for the various wire harness connectors, splices
and grounds.
KJAUDIO 8A - 3
AUDIO (Continued)

DIAGNOSIS AND TESTING - AMPLIFIER
CHOKE AND RELAY
Any diagnosis of the Audio system should
begin with the use of the DRB diagnostic tool.
For information on the use of the DRB, refer to
the appropriate Diagnostic Service Manual.
The amplifier choke and relay is used to switch
power to the individual speaker amplifiers used with
the premium speaker package. The amplifier choke
and relay is serviced only as a unit. If all of the
speakers are inoperative the amplifier choke and
relay should be inspected. Before replacement, make
the following inspections of the amplifier choke and
relay circuits. For complete circuit diagrams, refer to
the appropriate wiring information. The wiring infor-
mation includes wiring diagrams, proper wire and
connector repair procedures, details of wire harness
routing and retention, connector pin-out information
and location views for the various wire harness con-
nectors, splices and grounds.
(1)
Check the fused B(+) fuse in the junction block. If
OK, go to Step 2. If not OK, replace the faulty fuse.
(2) Check for battery voltage at the fused B(+) fuse
in the junction block. If OK, go to Step 3. If not OK,
repair the open fused B(+) circuit to the battery as
required.
(3) Disconnect the instrument panel wire harness
connector from the amplifier choke and relay. Check
for battery voltage at the fused B(+) circuit cavity of
the instrument panel wire harness connector for the
amplifier choke and relay. If OK, go to Step 4. If not
OK, repair the open fused B(+) circuit to the junction
block fuse as required.
(4) Probe the ground circuit cavity of the instru-
ment panel wire harness connector for the amplifier
choke and relay. Check for continuity to a good
ground. There should be continuity. If OK, go to Step
5. If not OK, repair the open ground circuit to ground
as required.
(5) Turn the ignition switch to the RUN position
and turn the radio ON. Check for battery voltage at
the radio 12-volt output circuit cavity of the instru-
ment panel wire harness connector for the amplifier
choke and relay. If OK, go to Step 6. If not OK,
repair the open radio 12-volt output circuit to the
radio as required.
(6) Turn the radio and ignition switches to the
OFF position. Reconnect the instrument panel wire
harness connector to the amplifier choke and relay.
Check for battery voltage at the amplified speaker
(+) circuit cavity of the instrument panel wire har-
ness connector for the amplifier choke and relay.
There should be zero volts. Turn the ignition and
radio switches to the ON position. There should now
be battery voltage. If OK, repair the open amplified
speaker (+) circuits to the speaker-mounted amplifi-ers as required. If not OK, replace the faulty ampli-
fier choke and relay.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove knee blocker cover and knee blocker.
(3) Disconnect the electrical harness connector
from the amplifier choke and relay (Fig. 1).
(4) Remove mounting screws and amplifier choke
and relay.
INSTALLATION
(1) Install the amplifier choke and relay.
(2) Install the mounting screws.
(3) Connect the electrical harness connector.
(4) Install knee blocker cover and knee blocker.
(5) Connect the battery negative cable.
ANTENNA BODY & CABLE
DESCRIPTION
The antenna body and cable is secured below the
fender panel by the antenna cap nut through a
mounting hole in the side of the right front fender.
The primary coaxial antenna cable is then routed
beneath the fender sheet metal and through a entry
hole in the right cowl side panel into the interior of
the vehicle. Inside the vehicle, the primary coaxial
cable is connected to a secondary instrument panel
antenna coaxial cable with an in-line connector that
is located behind the right kick panel. The secondary
coaxial cable is then routed behind the instrument
panel to the back of the radio.
Fig. 1 RADIO CHOKE
1 - RADIO CHOKE
2 - MOUNTING SCREWS
8A - 4 AUDIOKJ
AMPLIFIER CHOKE AND RELAY (Continued)