2002 JEEP LIBERTY light

EXHAUST SYSTEM
TABLE OF CONTENTS
page page
EXHAUST SYSTEM
DESCRIPTION..........................1
DIAGNOSIS AND TESTING - EXHAUST
SYSTEM.............................2
CATALYTIC CONVERTER
DESCRIPTION - CATALYTIC CONVERTER.....2
REMOVAL.............................2
INSPECTION...........................3
INSTALLATION..........................3CROSS-OVER PIPE
REMOVAL.............................4
INSTALLATION..........................4
HEAT SHIELDS
DESCRIPTION..........................4
MUFFLER
DESCRIPTION..........................4
REMOVAL.............................4
INSTALLATION..........................5
EXHAUST SYSTEM
DESCRIPTION
The basic exhaust system consists of an engine
exhaust manifold, exhaust down pipe, exhaust pipe,
exhaust heat shield(s), muffler and exhaust tailpipe
The exhaust system uses a single muffler.
The exhaust system must be properly aligned to
prevent stress, leakage and body contact. If the sys-
tem contacts any body panel, it will transfer objec-
tionable noises originating from the engine to the
body.
When inspecting an exhaust system, critically
inspect for cracked or loose joints, stripped screw or
bolt threads, corrosion damage and worn, cracked orbroken hangers. Replace all components that are
badly corroded or damaged. DO NOT attempt to
repair.
When replacement is required, use original equip-
ment parts (or equivalent). This will assure proper
alignment and provide acceptable exhaust noise lev-
els.
CAUTION: Avoid application of rust prevention com-
pounds or undercoating materials to exhaust sys-
tem floor pan exhaust heat shields. Light overspray
near the edges is permitted. Application of coating
will result in excessive floor pan temperatures and
objectionable fumes.
KJEXHAUST SYSTEM 11s - 1

FRAMES & BUMPERS
TABLE OF CONTENTS
page page
FRONT FASCIA
REMOVAL.............................1
INSTALLATION..........................2
REAR FASCIA
REMOVAL.............................2
INSTALLATION..........................2
REAR FASCIA SUPPORT
REMOVAL.............................3
INSTALLATION..........................3
FRAME
SPECIFICATIONS
SPECIFICATIONS - FRAME DIMENSIONS . . . 3
SPECIFICATIONS - TORQUE.............6
FRONT SKID PLATE
REMOVAL.............................6
INSTALLATION..........................6
ENGINE CRADLE CROSSMEMBER
REMOVAL.............................6
INSTALLATION..........................6TRANSFER CASE SKID PLATE
REMOVAL.............................7
INSTALLATION..........................7
REAR CROSSMEMBER
REMOVAL.............................7
INSTALLATION..........................7
FRONT TOW HOOK
REMOVAL.............................8
INSTALLATION..........................8
REAR TOW HOOK
REMOVAL.............................8
INSTALLATION..........................8
TRAILER HITCH
REMOVAL.............................9
INSTALLATION..........................9
FUEL TANK SKID PLATE
REMOVAL.............................9
INSTALLATION..........................9
FRONT FASCIA
REMOVAL
(1) Remove the grille. (Refer to 23 - BODY/EXTE-
RIOR/GRILLE - REMOVAL)
(2) Raise and support vehicle.
(3) Remove the front wheel opening flare moldings.
(Refer to 23 - BODY/EXTERIOR/FRONT WHEEL
OPENING FLARE MOLDINGS - REMOVAL)
(4) Remove the four screws through the lower air
dam (Fig. 1).
(5) Disconnect the electrical connectors:
²Fascia to grille opening reinforcement. (Fig. 1)
²Side repeater lights, both sides, if equipped.
(Fig. 2)
(6) Remove the six push pins from the grill sup-
port.
(7) Remove the rivets attaching the air dam to the
wheelhouse splash shield.
(8) Release the support tabs beneath the head-
lamps.
(9) Release the inner support clips from within the
fascia between the lights (Fig. 2).
(10) Remove the fascia.
Fig. 1 FRONT FASCIA
1 - ELECTRICAL CONNECTOR
2 - PUSH PINS
3 - FRONT FASCIA ASSEMBLY
4 - LOWER SCREWS
5 - PLASTIC RIVETS (2)
6 - INNER SUPPORT CLIPS
7 - SUPPORT TABS
KJFRAMES & BUMPERS 13 - 1

INSTALLATION
(1) Install the fascia.
(2) Connect the electrical connectors.
²Side repeater lights, both sides, if equipped.
²Fascia to grille opening reinforcement.
(3) Install the six push pin fasteners into the grill
support.
(4) Install the four screws through the lower air
damn.
(5) Install new rivets attaching the air dam to the
wheelhouse splash shield.
(6) Install the front wheel opening flare moldings.
(Refer to 23 - BODY/EXTERIOR/WHEEL OPENING
FLARE MOLDING - INSTALLATION)
(7) Install the grille. (Refer to 23 - BODY/EXTERI-
OR/GRILLE - INSTALLATION)
REAR FASCIA
REMOVAL
(1) Remove the wheel flares (rear). (Refer to 23 -
BODY/EXTERIOR/REAR WHEEL OPENING
FLARE MOLDINGS - REMOVAL)
(2) Remove the rear lamp units. (Refer to 8 -
ELECTRICAL/LAMPS/LIGHTING - EXTERIOR/
REAR LAMP UNIT - REMOVAL)(3) Remove the four side bolts. (Fig. 3)
(4) Remove the four bottom rivets.
(5) Remove the 3 bolts along the upper edge.
(6) Separate the side plastic retainers and remove
the fascia from the vehicle.
INSTALLATION
NOTE: Fascia must be pushed completely forward
to allow the plastic retainers full engagement in
their respective slots.
(1) Install the fascia and insert the plastic retain-
ers.
(2) Install the three upper bolts.
(3) Install the four side bolts.
(4) Install four bottom rivets.
(5) Install the rear lamp units. (Refer to 8 - ELEC-
TRICAL/LAMPS/LIGHTING - EXTERIOR/REAR
LAMP UNIT - INSTALLATION)
(6) Install the rear half wheel opening flares.
(Refer to 23 - BODY/EXTERIOR/WHEEL OPENING
FLARE MOLDING - INSTALLATION)
Fig. 2 FASCIA INNER SUPPORT
1 - INNER SUPPORT CLIP
2 - SIDE REPEATER CONNECTOR (IF EQUIPPED)
3 - FASCIA ASSEMBLY
4 - FOG LAMP
Fig. 3 REAR FASCIA
1 - REAR FASCIA ASSEMBLY
2 - PLASTIC RETAINERS
3 - FASCIA SUPPORT BRACKET
4 - SIDE BOLTS
5 - RIVETS
6 - UPPER BOLTS
13 - 2 FRAMES & BUMPERSKJ
FRONT FASCIA (Continued)

TRAILER HITCH
REMOVAL
(1) Remove the tow hooks, if equipped. (Refer to 13
- FRAME & BUMPERS/FRAME/REAR TOW HOOK
- REMOVAL)
(2) Disconnect trailer electrical connector.
(3) Support the hitch with a suitable lifting device.
(4) Remove the bolts and remove the trailer hitch.
(Fig. 12)
INSTALLATION
(1) Support the hitch with a suitable lifting device
and install the hitch.
(2) Install the bolts and tighten to 88 N´m (65 ft.
lbs.)
(3) Connect the electrical connector.
FUEL TANK SKID PLATE
REMOVAL
(1) Raise and support the vehicle.
(2) Support the skid plate with a suitable lifting
device.
(3) Remove the trailer hitch, if equipped. (Refer to
13 - FRAME & BUMPERS/FRAME/TRAILER
HITCH - REMOVAL)
(4) Remove the tow hooks, if not previously
removed. (Refer to 13 - FRAME & BUMPERS/
FRAME/REAR TOW HOOK - REMOVAL)
(5) Remove the bolts and remove the fuel tank
skid plate.
INSTALLATION
(1) Install the skid plate and support with a suit-
able lifting device.(2) Install the trailer hitch, if equipped. (Refer to
13 - FRAME & BUMPERS/FRAME/TRAILER
HITCH - INSTALLATION)
(3) Install the tow hooks, if equipped. (Refer to 13
- FRAME & BUMPERS/FRAME/REAR TOW HOOK
- INSTALLATION)
(4) Install the bolts and tighten to 88 N´m (65 ft.
lbs.).
Fig. 12 TRAILER HITCH
1 - BOLTS
2 - TRAILER LIGHTS ELECTRICAL CONNECTOR
3 - TRAILER HITCH
KJFRAMES & BUMPERS 13 - 9

(1) Remove protective cap at fuel rail test port.
Connect the 0±414 kPa (0-60 psi) fuel pressure gauge
(from gauge set 5069) to test port pressure fitting on
fuel rail (Fig. 20).The DRBtIII Scan Tool along
with the PEP module, the 500 psi pressure
transducer, and the transducer-to-test port
adapter may also be used in place of the fuel
pressure gauge.
(2) Start and warm engine and note pressure
gauge reading. Fuel pressure should be 339 kPa   34
kPa (49.2 psi   5 psi) at idle.
(3) If engine runs, but pressure is below 44.2 psi,
check for a kinked fuel supply line somewhere
between fuel rail and fuel pump module. If line is not
kinked, but specifications for either the Fuel Pump
Capacity, Fuel Pump Amperage or Fuel Pressure
Leak Down Tests were not met, replace lower section
of fuel pump module. Refer to Fuel Pump Module
Removal/Installation.
(4) If operating pressure is above 54.2 psi, electric
fuel pump is OK, but fuel pressure regulator is defec-
tive. Replace lower section of fuel pump module.
Refer to Fuel Pump Module Removal/Installation.
(5) Install protective cap to fuel rail test port.
DIAGNOSIS AND TESTING - FUEL PUMP
AMPERAGE TEST
This amperage (current draw) test is to be done in
conjunction with the Fuel Pump Pressure Test, Fuel
Pump Capacity Test and Fuel Pressure Leak Down
Test. Before performing the amperage test, be sure
the temperature of the fuel tank is above 50É F (10É
C).The DRBtScan Tool along with the DRB Low Cur-
rent Shunt (LCS) adapter (Fig. 21) and its test leads
will be used to check fuel pump amperage specifica-
tions.
(1) Be sure fuel tank contains fuel before starting
test. If tank is empty or near empty, amperage read-
ings will be incorrect.
(2) Obtain LCS adapter.
(3) Plug cable from LCS adapter into DRB scan
tool at SET 1 receptacle.
(4) Plug DRB into vehicle 16±way connector (data
link connector).
(5) Connect (-) and (+) test cable leads into LCS
adapter receptacles. Use10 amp (10A +)receptacle
and common (-) receptacles.
(6) Gain access to MAIN MENU on DRB screen.
(7) Press DVOM button on DRB.
(8) Using left/right arrow keys, highlight CHAN-
NEL 1 function on DRB screen.
(9) Press ENTER three times.
(10) Using up/down arrow keys, highlight RANGE
on DRB screen (screen will default to 2 amp scale).
(11) Press ENTER to change 2 amp scale to 10
amp scale.This step must be done to prevent
damage to DRB scan tool or LCS adapter
(blown fuse).
(12) Remove cover from Power Distribution Center
(PDC).
(13) Remove fuel pump relay from PDC. Refer to
label on PDC cover for relay location.
Fig. 20 FUEL PRESSURE TEST GAUGE (TYPICAL
GAUGE INSTALLATION AT TEST PORT)
1 - SERVICE (TEST) PORT
2 - FUEL PRESSURE TEST GAUGE
3 - FUEL RAIL
Fig. 21 LOW CURRENT SHUNT
1 - LOW CURRENT SHUNT ADAPTER
2 - PLUG TO DRB
3 - TEST LEAD RECEPTACLES
14 - 16 FUEL DELIVERYKJ
FUEL PUMP (Continued)

(14) If fuel injectors are to be removed, refer to
Fuel Injector Removal/Installation.
INSTALLATION
2.4L Engine
(1) If fuel injectors are to be installed, refer to Fuel
Injector Removal/Installation.
(2) Clean out fuel injector machined bores in
intake manifold.
(3) Apply a small amount of engine oil to each fuel
injector o-ring. This will help in fuel rail installation.
(4) Position fuel rail/fuel injector assembly to
machined injector openings in intake manifold.
(5) Guide each injector into cylinder head. Be care-
ful not to tear injector o-rings.
(6) Push fuel rail down until fuel injectors have
bottomed on shoulders.
(7) Install 2 fuel rail mounting bolts and tighten.
Refer to torque specifications.
(8) Connect electrical connectors at all fuel injec-
tors. To install connector, refer to (Fig. 37). Push con-
nector onto injector (1) and then push and lock red
colored slider (2). Verify connector is locked to injec-
tor by lightly tugging on connector.
(9) Snap 2 injection wiring harness clips (Fig. 35)
into brackets.
(10) Connect 2 main engine harness connectors at
rear of intake manifold (Fig. 34).
(11) Tighten 5 intake manifold mounting bolts.
Refer to Engine Torque Specifications.
(12) Install PCV valve and hose.
(13) Install thermostat and radiator hose. Fill with
coolant. Refer to Cooling.
(14) Connect necessary vacuum lines to throttle
body.
(15) Connect fuel line latch clip and fuel line to
fuel rail. Refer to Quick-Connect Fittings.
(16) Install air duct to throttle body.
(17) Connect battery cable to battery.
(18) Start engine and check for leaks.
3.7L Engine
(1) If fuel injectors are to be installed, refer to Fuel
Injector Removal/Installation.
(2) Clean out fuel injector machined bores in
intake manifold.
(3) Apply a small amount of engine oil to each fuel
injector o-ring. This will help in fuel rail installation.
(4) Position fuel rail/fuel injector assembly to
machined injector openings in cylinder head.
(5) Guide each injector into cylinder head. Be care-
ful not to tear injector o-rings.
(6) Pushrightside of fuel rail down until fuel
injectors have bottomed on cylinder head shoulder.Pushleftfuel rail down until injectors have bot-
tomed on cylinder head shoulder.
(7) Install 4 fuel rail mounting bolts and tighten.
Refer to torque specifications.
(8) Install 6 ignition coils. Refer to Ignition Coil
Removal/Installation.
(9) Connect electrical connectors to throttle body.
(10) Connect electrical connectors at all fuel injec-
tors. To install connector, refer to (Fig. 37). Push con-
nector onto injector (1) and then push and lock red
colored slider (2). Verify connector is locked to injec-
tor by lightly tugging on connector.
(11) Connect necessary vacuum lines to throttle
body.
(12) Connect fuel line latch clip and fuel line to
fuel rail. Refer to Quick-Connect Fittings.
(13) Install air box to throttle body.
(14) Install air duct to air box.
(15) Connect battery cable to battery.
(16) Start engine and check for leaks.
FUEL TANK
DESCRIPTION
The fuel tank is constructed of a plastic material.
Its main functions are for fuel storage and for place-
ment of the fuel pump module, and certain ORVR
components.
OPERATION
All models pass a full 360 degree rollover test
without fuel leakage. To accomplish this, fuel and
vapor flow controls are required for all fuel tank con-
nections.
A check (control) valve is mounted into the top sec-
tion of the 2±piece fuel pump module. Refer to Fuel
Tank Check Valve for additional information.
An evaporation control system is connected to the
fuel tank to reduce emissions of fuel vapors into the
atmosphere. When fuel evaporates from the fuel
tank, vapors pass through vent hoses or tubes to a
charcoal canister where they are temporarily held.
When the engine is running, the vapors are drawn
into the intake manifold. Certain models are also
equipped with a self-diagnosing system using a Leak
Detection Pump (LDP) and/or an ORVR system.
Refer to Emission Control System for additional
information.
14 - 24 FUEL DELIVERYKJ
FUEL RAIL (Continued)

INSTALLATION
2.4L
(1) Clean out machined hole in engine block.
(2) Apply a small amount of engine oil to sensor
o-ring.(3) Install sensor into engine block with a slight
rocking action. Do not twist sensor into position as
damage to o-ring may result.
CAUTION: Before tightening sensor mounting bolt,
be sure sensor is completely flush to cylinder
block. If sensor is not flush, damage to sensor
mounting tang may result.
(4) Install mounting bolt and tighten to 28 N´m
(21 ft. lbs.) torque.
(5) Connect electrical connector to sensor.
3.7L
(1) Clean out machined hole in engine block.
(2) Apply a small amount of engine oil to sensor
o-ring.
(3) Install sensor into engine block with a slight
rocking and twisting action.
CAUTION: Before tightening sensor mounting bolt,
be sure sensor is completely flush to cylinder
block. If sensor is not flush, damage to sensor
mounting tang may result.
(4) Install mounting bolt and tighten to 28 N´m
(21 ft. lbs.) torque.
(5) Connect electrical connector to sensor.
(6) Lower vehicle.
Fig. 6 CKP SENSOR LOCATION-2.4L
1 - RIGHT FRONT ENGINE MOUNT
2 - CKP SENSOR
3 - MOUNTING BOLT
4 - ELECTRICAL CONNECTOR
Fig. 7 CKP AND O-RING-2.4L
1 - CKP SENSOR
2 - O-RING
Fig. 8 CKP - 3.7L
1 - MOUNTING BOLT
2 - CKP SENSOR
3 - O-RING
14 - 32 FUEL INJECTIONKJ
CRANKSHAFT POSITION SENSOR (Continued)

IDLE AIR CONTROL MOTOR
DESCRIPTION
The IAC stepper motor is mounted to the throttle
body, and regulates the amount of air bypassing the
control of the throttle plate. As engine loads and
ambient temperatures change, engine rpm changes.
A pintle on the IAC stepper motor protrudes into a
passage in the throttle body, controlling air flow
through the passage. The IAC is controlled by the
Powertrain Control Module (PCM) to maintain the
target engine idle speed.
OPERATION
At idle, engine speed can be increased by retract-
ing the IAC motor pintle and allowing more air to
pass through the port, or it can be decreased by
restricting the passage with the pintle and diminish-
ing the amount of air bypassing the throttle plate.
The IAC is called a stepper motor because it is
moved (rotated) in steps, or increments. Opening the
IAC opens an air passage around the throttle blade
which increases RPM.
The PCM uses the IAC motor to control idle speed
(along with timing) and to reach a desired MAP dur-
ing decel (keep engine from stalling).
The IAC motor has 4 wires with 4 circuits. Two of
the wires are for 12 volts and ground to supply elec-
trical current to the motor windings to operate the
stepper motor in one direction. The other 2 wires are
also for 12 volts and ground to supply electrical cur-
rent to operate the stepper motor in the opposite
direction.
To make the IAC go in the opposite direction, the
PCM just reverses polarity on both windings. If only
1 wire is open, the IAC can only be moved 1 step
(increment) in either direction. To keep the IAC
motor in position when no movement is needed, the
PCM will energize both windings at the same time.
This locks the IAC motor in place.
In the IAC motor system, the PCM will count
every step that the motor is moved. This allows the
PCM to determine the motor pintle position. If the
memory is cleared, the PCM no longer knows the
position of the pintle. So at the first key ON, the
PCM drives the IAC motor closed, regardless of
where it was before. This zeros the counter. Fromthis point the PCM will back out the IAC motor and
keep track of its position again.
When engine rpm is above idle speed, the IAC is
used for the following:
²Off-idle dashpot (throttle blade will close quickly
but idle speed will not stop quickly)
²Deceleration air flow control
²A/C compressor load control (also opens the pas-
sage slightly before the compressor is engaged so
that the engine rpm does not dip down when the
compressor engages)
²Power steering load control
The PCM can control polarity of the circuit to con-
trol direction of the stepper motor.
IAC Stepper Motor Program:The PCM is also
equipped with a memory program that records the
number of steps the IAC stepper motor most recently
advanced to during a certain set of parameters. For
example: The PCM was attempting to maintain a
1000 rpm target during a cold start-up cycle. The last
recorded number of steps for that may have been
125. That value would be recorded in the memory
cell so that the next time the PCM recognizes the
identical conditions, the PCM recalls that 125 steps
were required to maintain the target. This program
allows for greater customer satisfaction due to
greater control of engine idle.
Another function of the memory program, which
occurs when the power steering switch (if equipped),
or the A/C request circuit, requires that the IAC step-
per motor control engine rpm, is the recording of the
last targeted steps into the memory cell. The PCM
can anticipate A/C compressor loads. This is accom-
plished by delaying compressor operation for approx-
imately 0.5 seconds until the PCM moves the IAC
stepper motor to the recorded steps that were loaded
into the memory cell. Using this program helps elim-
inate idle-quality changes as loads change. Finally,
the PCM incorporates a9No-Load9engine speed lim-
iter of approximately 1800 - 2000 rpm, when it rec-
ognizes that the TPS is indicating an idle signal and
IAC motor cannot maintain engine idle.
A (factory adjusted) set screw is used to mechani-
cally limit the position of the throttle body throttle
plate.Never attempt to adjust the engine idle
speed using this screw.All idle speed functions are
controlled by the IAC motor through the PCM.
KJFUEL INJECTION 14 - 35