2002 JEEP LIBERTY Cylinder head repair

the pan, it will drain first because it is heavier than
oil. An alternative method is to operate engine for a
short period to churn the oil. After this is done,
remove engine dipstick and inspect for water glob-
ules. Also inspect transmission dipstick for water
globules and transmission fluid cooler for leakage.
WARNING: WITH RADIATOR PRESSURE TESTER
TOOL INSTALLED ON RADIATOR, DO NOT ALLOW
PRESSURE TO EXCEED 124 KPA (18 PSI). PRES-
SURE WILL BUILD UP QUICKLY IF A COMBUSTION
LEAK IS PRESENT. TO RELEASE PRESSURE,
ROCK TESTER FROM SIDE TO SIDE. WHEN
REMOVING TESTER, DO NOT TURN TESTER MORE
THAN 1/2 TURN IF SYSTEM IS UNDER PRESSURE.
Operate engine without pressure cap on radiator
until thermostat opens. Attach a Pressure Tester to
filler neck. If pressure builds up quickly it indicates a
combustion leak exists. This is usually the result of a
cylinder head gasket leak or crack in engine. Repair
as necessary.
If there is not an immediate pressure increase,
pump the Pressure Tester. Do this until indicated
pressure is within system range of 110 kPa (16 psi).
Fluctuation of gauge pointer indicates compression or
combustion leakage into cooling system.
Because the vehicle is equipped with a catalytic
converter,do notremove spark plug cables or short
out cylinders to isolate compression leak.
If the needle on dial of pressure tester does not
fluctuate, race engine a few times to check for an
abnormal amount of coolant or steam. This would be
emitting from exhaust pipe. Coolant or steam from
exhaust pipe may indicate a faulty cylinder head gas-
ket, cracked engine cylinder block or cylinder head.A convenient check for exhaust gas leakage into
cooling system is provided by a commercially avail-
able Block Leak Check tool. Follow manufacturers
instructions when using this product.
COMBUSTION LEAKAGE TEST - WITHOUT
PRESSURE TESTER
DO NOT WASTE reusable coolant. If solution is
clean, drain coolant into a clean container for reuse.
WARNING: DO NOT REMOVE CYLINDER BLOCK
DRAIN PLUGS OR LOOSEN RADIATOR DRAIN-
COCK WITH SYSTEM HOT AND UNDER PRESSURE.
SERIOUS BURNS FROM COOLANT CAN OCCUR.
Drain sufficient coolant to allow thermostat
removal. (Refer to 7 - COOLING/ENGINE/ENGINE
COOLANT THERMOSTAT - REMOVAL). Remove
accessory drive belt (Refer to 7 - COOLING/ACCES-
SORY DRIVE/DRIVE BELTS - REMOVAL).
Add coolant to radiator to bring level to within 6.3
mm (1/4 in) of top of thermostat housing.
CAUTION: Avoid overheating. Do not operate
engine for an excessive period of time. Open drain-
cock immediately after test to eliminate boil over.
Start engine and accelerate rapidly three times, to
approximately 3000 rpm while observing coolant. If
internal engine combustion gases are leaking into
cooling system, bubbles will appear in coolant. If bub-
bles do not appear, internal combustion gas leakage
is not present.
KJCOOLING 7 - 5
COOLING (Continued)

CONDITION POSSIBLE CAUSES CORRECTION
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.
TEMPERATURE GAUGE READING
IS INCONSISTENT (FLUCTUATES,
CYCLES OR IS ERRATIC)1. During cold weather operation,
with the heater blower in the high
position, the gauge reading may
drop slightly.1. A normal condition. No correction
is necessary.
2. Temperature gauge or engine
mounted gauge sensor defective or
shorted. Also, corroded or loose
wiring in this circuit.2. Check operation of gauge and
repair if necessary. Refer to Group
8J, Instrument cluster.
3. Gauge reading rises when
vehicle is brought to a stop after
heavy use (engine still running)3. A normal condition. No correction
is necessary. Gauge should return
to normal range after vehicle is
driven.
4. Gauge reading high after
re-starting a warmed up (hot)
engine.4. A normal condition. No correction
is necessary. The gauge should
return to normal range after a few
minutes of engine operation.
5. Coolant level low in cooling
system (air will build up in the
cooling system causing the
thermostat to open late).5. Check and correct coolant leaks.
(Refer to 7 - COOLING -
DIAGNOSIS AND TESTING).
7 - 8 COOLINGKJ
COOLING (Continued)

CONDITION POSSIBLE CAUSES CORRECTION
6. Cylinder head gasket leaking
allowing exhaust gas to enter
cooling system causing a
thermostat to open late.6. (a) Check for cylinder head
gasket leaks. (Refer to 7 -
COOLING - DIAGNOSIS AND
TESTING).
(b) Check for coolant in the engine
oil. Inspect for white steam emitting
from the exhaust system. Repair as
necessary.
7. Water pump impeller loose on
shaft.7. Check water pump and replace
as necessary. (Refer to 7 -
COOLING/ENGINE/WATER PUMP -
DIAGNOSIS AND TESTING).
8. Loose accessory drive belt.
(water pump slipping)8. (Refer to 7 - COOLING/
ACCESSORY DRIVE/DRIVE BELTS
- DIAGNOSIS AND TESTING).
Check and correct as necessary.
9. Air leak on the suction side of
the water pump allows air to build
up in cooling system causing
thermostat to open late.9. Locate leak and repair as
necessary.
PRESSURE CAP IS BLOWING
OFF STEAM AND/OR COOLANT
TO COOLANT TANK.
TEMPERATURE GAUGE READING
MAY BE ABOVE NORMAL BUT
NOT HIGH. COOLANT LEVEL MAY
BE HIGH IN COOLANT RESERVE/
OVERFLOW TANK1. Pressure relief valve in pressure
bottle cap is defective.1. Check condition of radiator cap
and cap seals. (Refer to 7 -
COOLING/ENGINE/RADIATOR
PRESSURE CAP - DIAGNOSIS
AND TESTING). Replace cap as
necessary.
COOLANT LOSS TO THE
GROUND WITHOUT PRESSURE
CAP BLOWOFF. GAUGE READING
HIGH OR HOT1. Coolant leaks in radiator, cooling
system hoses, water pump or
engine.1. Pressure test and repair as
necessary. (Refer to 7 - COOLING -
DIAGNOSIS AND TESTING).
DETONATION OR PRE-IGNITION
(NOT CAUSED BY IGNITION
SYSTEM). GAUGE MAY OR MAY
NOT BE READING HIGH1. Engine overheating. 1. Check reason for overheating
and repair as necessary.
2. Freeze point of coolant not
correct. Mixture is too rich or too
lean.2. Check coolant concentration.
(Refer to 7 - COOLING/ENGINE/
COOLANT - DESCRIPTION) and
adjust ratio as required.
KJCOOLING 7 - 9
COOLING (Continued)

WARNING: WITH RADIATOR PRESSURE TESTER
TOOL INSTALLED ON RADIATOR, DO NOT ALLOW
PRESSURE TO EXCEED 124 KPA (18 PSI). PRES-
SURE WILL BUILD UP QUICKLY IF A COMBUSTION
LEAK IS PRESENT. TO RELEASE PRESSURE,
ROCK TESTER FROM SIDE TO SIDE. WHEN
REMOVING TESTER, DO NOT TURN TESTER MORE
THAN 1/2 TURN IF SYSTEM IS UNDER PRESSURE.
Operate engine without pressure cap on radiator
until thermostat opens. Attach a Pressure Tester to
filler neck. If pressure builds up quickly it indicates a
combustion leak exists. This is usually the result of a
cylinder head gasket leak or crack in engine. Repair
as necessary.
If there is not an immediate pressure increase,
pump the Pressure Tester. Do this until indicated
pressure is within system range of 110 kPa (16 psi).
Fluctuation of gauge pointer indicates compression or
combustion leakage into cooling system.
Because the vehicle is equipped with a catalytic
converter,do notremove spark plug cables or short
out cylinders to isolate compression leak.
If the needle on dial of pressure tester does not
fluctuate, race engine a few times to check for an
abnormal amount of coolant or steam. This would be
emitting from exhaust pipe. Coolant or steam from
exhaust pipe may indicate a faulty cylinder head gas-
ket, cracked engine cylinder block or cylinder head.
A convenient check for exhaust gas leakage into
cooling system is provided by a commercially avail-able Block Leak Check tool. Follow manufacturers
instructions when using this product.
COMBUSTION LEAKAGE TEST - WITHOUT
PRESSURE TESTER
DO NOT WASTE reusable coolant. If solution is
clean, drain coolant into a clean container for reuse.
WARNING: DO NOT REMOVE CYLINDER BLOCK
DRAIN PLUGS OR LOOSEN RADIATOR DRAIN-
COCK WITH SYSTEM HOT AND UNDER PRESSURE.
SERIOUS BURNS FROM COOLANT CAN OCCUR.
Drain sufficient coolant to allow thermostat
removal. (Refer to 7 - COOLING/ENGINE/ENGINE
COOLANT THERMOSTAT - REMOVAL). Remove
accessory drive belt (Refer to 7 - COOLING/ACCES-
SORY DRIVE/DRIVE BELTS - REMOVAL).
Add coolant to radiator to bring level to within 6.3
mm (1/4 in) of top of thermostat housing.
CAUTION: Avoid overheating. Do not operate
engine for an excessive period of time. Open drain-
cock immediately after test to eliminate boil over.
Start engine and accelerate rapidly three times, to
approximately 3000 rpm while observing coolant. If
internal engine combustion gases are leaking into
cooling system, bubbles will appear in coolant. If bub-
bles do not appear, internal combustion gas leakage
is not present.
7s - 4 COOLING - 2.4LKJ
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)

CONDITION POSSIBLE CAUSES CORRECTION
TEMPERATURE GAUGE READING
IS INCONSISTENT (FLUCTUATES,
CYCLES OR IS ERRATIC)1. During cold weather operation,
with the heater blower in the high
position, the gauge reading may
drop slightly.1. A normal condition. No correction
is necessary.
2. Temperature gauge or engine
mounted gauge sensor defective or
shorted. Also, corroded or loose
wiring in this circuit.2. Check operation of gauge and
repair if necessary. Refer to Group
8J, Instrument cluster.
3. Gauge reading rises when
vehicle is brought to a stop after
heavy use (engine still running)3. A normal condition. No correction
is necessary. Gauge should return
to normal range after vehicle is
driven.
4. Gauge reading high after
re-starting a warmed up (hot)
engine.4. A normal condition. No correction
is necessary. The gauge should
return to normal range after a few
minutes of engine operation.
5. Coolant level low in cooling
system (air will build up in the
cooling system causing the
thermostat to open late).5. Check and correct coolant leaks.
(Refer to 7 - COOLING -
DIAGNOSIS AND TESTING).
6. Cylinder head gasket leaking
allowing exhaust gas to enter
cooling system causing a
thermostat to open late.6. (a) Check for cylinder head
gasket leaks. (Refer to 7 -
COOLING - DIAGNOSIS AND
TESTING).
(b) Check for coolant in the engine
oil. Inspect for white steam emitting
from the exhaust system. Repair as
necessary.
7. Water pump impeller loose on
shaft.7. Check water pump and replace
as necessary. (Refer to 7 -
COOLING/ENGINE/WATER PUMP -
DIAGNOSIS AND TESTING).
8. Loose accessory drive belt.
(water pump slipping)8. (Refer to 7 - COOLING/
ACCESSORY DRIVE/DRIVE BELTS
- DIAGNOSIS AND TESTING).
Check and correct as necessary.
9. Air leak on the suction side of
the water pump allows air to build
up in cooling system causing
thermostat to open late.9. Locate leak and repair as
necessary.
PRESSURE CAP IS BLOWING
OFF STEAM AND/OR COOLANT
TO COOLANT TANK.
TEMPERATURE GAUGE READING
MAY BE ABOVE NORMAL BUT
NOT HIGH. COOLANT LEVEL MAY
BE HIGH IN COOLANT RESERVE/
OVERFLOW TANK1. Pressure relief valve in pressure
bottle cap is defective.1. Check condition of radiator cap
and cap seals. (Refer to 7 -
COOLING/ENGINE/RADIATOR
PRESSURE CAP - DIAGNOSIS
AND TESTING). Replace cap as
necessary.
7s - 8 COOLING - 2.4LKJ
COOLING - 2.4L (Continued)

flip-up glass ajar switch, the hood ajar switch (in
required markets only), and the Remote Keyless
Entry (RKE) module to control the features of the
optional Vehicle Theft Security System (VTSS).
Hard wired circuitry connects the BCM to the elec-
trical system of the vehicle. These hard wired circuits
are integral to several wire harnesses, which are
routed throughout the vehicle and retained by many
different methods. These circuits may be connected to
each other, to the vehicle electrical system and to the
BCM through the use of a combination of soldered
splices, splice block connectors, and many different
types of wire harness terminal connectors and insu-
lators. Refer to the appropriate wiring information.
The wiring information includes wiring diagrams,
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
harness connectors, splices and grounds.
Many of the electronic features in the vehicle con-
trolled or supported by the BCM are programmable
using a customer programming procedure or the
DRBIIItscan tool. In addition, the BCM software is
Flash compatible, which means it can be repro-
grammed using Flash reprogramming procedures.
However, if any of the BCM hardware components is
damaged or faulty, the entire BCM unit must be
replaced.
OPERATION
The microprocessor-based Body Control Module
(BCM) monitors many hard wired switch and sensor
inputs as well as those resources it shares with other
electronic modules in the vehicle through its commu-
nication over the Programmable Communications
Interface (PCI) data bus network. The internal pro-
gramming and all of these inputs allow the BCM
microprocessor to determine the tasks it needs to
perform and their priorities, as well as both the stan-
dard and optional features that it should provide.
The BCM programming then performs those tasks
and provides those features through both PCI data
bus communication with other electronic modules
and through hard wired outputs through a number of
driver circuits, relays, and actuators. These outputs
allow the BCM the ability to control numerous acces-
sory systems in the vehicle.
The BCM operates on battery current received
through a fuse in the Junction Block (JB) on a non-
switched fused B(+) circuit, through another fuse in
the JB on a fused ignition switch output (run-start)
circuit, and through a third fuse in the JB on a fused
ignition switch output (run-acc) circuit. This arrange-
ment allows the BCM to provide some features
regardless of the ignition switch position, while other
features will operate only with the ignition switch inthe On, Start, and/or Accessory positions. All of the
battery current circuits are connected to the BCM
through the JB/BCM connector. The BCM receives
ground through five separate circuits. Three of these
circuits are connected to the BCM through a connec-
tor and take out of the instrument panel wire har-
ness on three separate ground circuits, while the
other two circuits are connected to the BCM through
the JB/BCM connector. All of these circuits are
grounded through a splice block located in the instru-
ment panel wire harness with an eyelet terminal con-
nector that is secured by a nut to a ground stud on
the driver side instrument panel end bracket near
the JB.
The BCM monitors its own internal circuitry as
well as many of its input and output circuits, and
will store a Diagnostic Trouble Code (DTC) in elec-
tronic memory for any failure it detects. These DTCs
can be retrieved and diagnosed using a DRBIIItscan
tool. Refer to the appropriate diagnostic information.
HARD WIRED INPUTS The hard wired inputs to
the BCM include the following:
²A/C on/off control
²Ambient temperature sensor signal
²Body control module flash enable
²Door lock switch mux
²Driver door ajar switch sense
²Flip-up glass ajar switch sense
²Flip-up glass release switch sense
²Fog lamp switch sense
²Front wiper park switch sense
²Front wiper switch mux
²Front washer pump driver
²Fused B(+)
²Fused ignition switch output (run-acc)
²Fused ignition switch output (run-start)
²Headlamp switch mux
²High beam switch sense
²Hood ajar switch sense - premium with
VTSS - in markets where required only
²Key-in ignition switch sense
²Left cylinder lock switch sense - premium
with VTSS only - omitted in some markets as
required
²Panel lamps dimmer switch mux
²Passenger doors ajar switch sense (input
from three ajar switches connected in parallel)
²Radio control mux - premium with remote
radio switches only
²Rear courtesy lamp control
²Rear window defogger control
²Rear wiper intermittent driver
²Rear wiper on driver
²Right cylinder lock switch sense - premium
with VTSS only - omitted in some markets as
required
KJELECTRONIC CONTROL MODULES 8E - 5
BODY CONTROL MODULE (Continued)

(3) Install and tighten the battery hold down
bracket retaining bolt. Tighten the bolt to 4 N´m (20
in. lbs.).
(4) Reconnect the battery negative cable terminal
clamp to the battery negative terminal post. Tighten
the terminal clamp pinch-bolt hex nut to 8.4 N´m (75
in. lbs.).
BATTERY CABLES
DESCRIPTION
The battery cables (Fig. 18) are large gauge,
stranded copper wires sheathed within a heavy plas-
tic or synthetic rubber insulating jacket. The wire
used in the battery cables combines excellent flexibil-
ity and reliability with high electrical current carry-
ing capacity. The battery cables feature a clamping
type female battery terminal made of soft lead that is
die cast onto one end of the battery cable wire. A
square headed pinch-bolt and hex nut are installed
at the open end of the female battery terminal clamp.
Large eyelet type terminals are crimped onto the
opposite end of the battery cable wire and then sol-
der-dipped. The battery positive cable wires have a
red insulating jacket to provide visual identificationand feature a larger female battery terminal clamp
to allow connection to the larger battery positive ter-
minal post. The battery negative cable wires have a
black insulating jacket and a smaller female battery
terminal clamp.
The battery cables cannot be repaired and, if dam-
aged or faulty they must be replaced. Both the bat-
tery positive and negative cables are available for
service replacement only as a unit with the battery
wire harness, which may include portions of the wir-
ing circuits for the generator and other components
on some models. Refer to the appropriate wiring
information in this service manual for the location of
the proper battery cable wire harness diagrams. The
wiring information also includes proper wire and con-
nector repair procedures, further details on wire har-
ness routing and retention, as well as pin-out and
location views for the various wire harness connec-
tors, splices and grounds.
OPERATION
The battery cables connect the battery terminal
posts to the vehicle electrical system. These cables
also provide a path back to the battery for electrical
current generated by the charging system for restor-
ing the voltage potential of the battery. The female
battery terminal clamps on the ends of the battery
cable wires provide a strong and reliable connection
of the battery cable to the battery terminal posts.
The terminal pinch bolts allow the female terminal
clamps to be tightened around the male terminal
posts on the top of the battery. The eyelet terminals
secured to the opposite ends of the battery cable
wires from the female battery terminal clamps pro-
vide secure and reliable connection of the battery
cables to the vehicle electrical system.
The battery positive cable terminal clamp is die
cast onto the ends of two wires. One wire has an eye-
let terminal that connects the battery positive cable
to the B(+) terminal studs of the Power Distribution
Center (PDC), and the other wire has an eyelet ter-
minal that connects the battery positive cable to the
B(+) terminal stud of the engine starter motor sole-
noid. The battery negative cable terminal clamp is
also die cast onto the ends of two wires. One wire
has an eyelet terminal that connects the battery neg-
ative cable to the vehicle powertrain through a stud
on the left side of the engine cylinder block. The
other wire has an eyelet terminal that connects the
battery negative cable to the vehicle body through a
ground stud on the left wheel house, near the bat-
tery.
Fig. 18 Battery Cables - Typical
1 - Battery
2 - Radiator Crossmember
3 - Terminal Clamps
4 - Fender Inner Shield
5 - Negative Cable
6 - Positive Cable
8F - 18 BATTERY SYSTEMKJ
BATTERY HOLDDOWN (Continued)