2002 JEEP LIBERTY Workshop Manual

CONDITION POSSIBLE CAUSES CORRECTION
HEADLAMPS WILL NOT
SWITCH FROM HIGH TO
LOW BEAMS, OR FROM
LOW TO HIGH BEAMS1. Faulty relay. 1. Test and replace low beam or high beam
relay as required. (Note: Vehicles with a
DRL relay do not use a high beam relay.
The DRL relay cannot be tested. Replace
DRL relay with a known good unit and
check operation. Replace DRL relay as
required.)
2. Faulty switch. 2. Test and replace multi-function switch as
required.
3. Faulty BCM inputs or outputs. 3. Use a DRBIIITscan tool to test the BCM
inputs and outputs. Refer to the appropriate
diagnostic information.
HEADLAMP LEVELING
Before performing the following tests, confirm
whether the park lamps operate satisfactorily. If thepark lamps are inoperative, diagnose and repair that
problem before attempting to repair the Headlamp
Leveling System.
CONDITION POSSIBLE CAUSES CORRECTION
ONE LEVELING MOTOR
IS INOPERATIVE1. Faulty ground circuit. 1. Test and repair open leveling motor
ground circuit as required.
2. Faulty feed circuit. 2. Test and repair open leveling motor feed
circuit as required.
3. Faulty signal circuit. 3. Test and repair open headlamp adjust
signal circuit as required.
4. Faulty motor. 4. Test and replace headlamp leveling
motor as required.
BOTH LEVELING
MOTORS ARE
INOPERATIVE1. Faulty switch ground circuit. 1. Test and repair open leveling switch
ground circuit as required.
2. Faulty motor ground circuit. 2. Test and repair open leveling motor
ground circuit as required.
3. Faulty switch feed circuit. 3. Test and repair open leveling switch feed
circuit as required.
4. Faulty motor feed circuit. 4. Test and repair open leveling motor feed
circuit as required.
5. Faulty signal circuit. 5. Test and repair open or shorted leveling
motor signal circuit as required.
6. Faulty switch. 6. Test and replace leveling switch as
required.
7. Faulty motors. 7. Test and replace leveling motors as
required.
8Ls - 12 LAMPSKJ
LAMPS/LIGHTING - EXTERIOR (Continued)

PARK LAMPS
CONDITION POSSIBLE CAUSES CORRECTION
PARK LAMP DOES NOT
ILLUMINATE1. Faulty or missing fuse. 1. Test and replace park lamp fuse as
required.
2. Faulty or missing bulb. 2. Test and replace park lamp bulb as
required.
3. Faulty or missing relay. 3. Test and replace park lamp relay as
required.
4. Faulty switch. 4. Test and replace multi-function switch as
required.
5. Faulty ground circuit. 5. Test and repair open park lamp ground
circuit as required.
6. Faulty feed circuit. 6. Test and repair open park lamp relay
output circuit as required.
7. Faulty BCM inputs or outputs. 7. Use a DRBIIITscan tool to test the BCM
inputs and outputs. Refer to the appropriate
diagnostic information.
PARK LAMP DOES NOT
EXTINGUISH1. Faulty relay. 1. Test and replace park lamp relay as
required.
2. Faulty switch. 2. Test and replace multi-function switch as
required.
3. Faulty feed circuit. 3. Test and repair shorted park lamp relay
output circuit as required.
4. Faulty BCM inputs or outputs. 4. Use a DRBIIITscan tool to test the BCM
inputs and outputs. Refer to the appropriate
diagnostic information.
REAR FOG LAMPS
CONDITION POSSIBLE CAUSES CORRECTION
REAR FOG LAMP DOES
NOT ILLUMINATE1. Faulty or missing fuse. 1. Test and replace rear fog lamp fuse as
required.
2. Faulty or missing bulb. 2. Test and replace rear fog lamp bulb as
required.
3. Faulty or missing relay. 3. Test and replace rear fog lamp relay as
required.
4. Faulty switch. 4. Test and replace multi-function switch as
required.
5. Faulty ground circuit. 5. Test and repair open rear fog lamp
ground circuit as required.
6. Faulty feed circuit. 6. Test and repair open rear fog lamp relay
output circuit as required.
7. Faulty BCM inputs or outputs. 7. Use a DRBIIITscan tool to test the BCM
inputs and outputs. Refer to the appropriate
diagnostic information.
KJLAMPS8Ls-13
LAMPS/LIGHTING - EXTERIOR (Continued)

CONDITION POSSIBLE CAUSES CORRECTION
REAR FOG LAMP DOES
NOT EXTINGUISH1. Faulty relay. 1. Test and replace rear fog lamp relay as
required.
2. Faulty switch. 2. Test and replace multi-function switch as
required.
3. Faulty feed circuit. 3. Test and repair shorted rear fog lamp
relay output circuit as required.
4. Faulty BCM inputs or outputs. 4. Use a DRBIIITscan tool to test the BCM
inputs and outputs. Refer to the appropriate
diagnostic information.
TURN SIGNAL LAMPS
CONDITION POSSIBLE CAUSES CORRECTION
ONE TURN SIGNAL LAMP
DOES NOT ILLUMINATE1. Faulty or missing bulb. 1. Test and replace turn signal bulb as
required.
2. Faulty ground circuit. 2. Test and repair open ground circuit as
required.
3. Faulty feed circuit. 3. Test and repair open right or left turn
signal circuit as required.
ALL RIGHT SIDE AND/OR
ALL LEFT SIDE TURN
SIGNAL LAMPS DO NOT
FLASH1. Faulty sense circuit. 1. Test and repair open right or left turn
switch sense circuit as required.
2. Faulty switch. 2. Test and replace multi-function switch as
required.
3. Faulty flasher. 3. Replace hazard switch/combination
flasher with a known good unit and check
operation. Replace hazard switch/
combination flasher unit as required.
4. Faulty signal circuit. 4. Test and repair open right or left turn
signal circuit as required.
ALL RIGHT SIDE OR ALL
LEFT SIDE TURN
SIGNALS FLASH TOO
RAPIDLY (MORE THAN
100 FLASHES PER
MINUTE)1. Faulty or missing bulb. 1. Test and replace faulty bulb as required.
2. Faulty ground circuit. 2. Test and repair open ground circuit as
required.
3. Faulty signal circuit 3. Test and repair open right or left turn
signal circuit as required.
4. Faulty flasher. 4. Replace hazard switch/combination
flasher with a known good unit and check
operation. Replace hazard switch/
combination flasher unit as required.
8Ls - 14 LAMPSKJ
LAMPS/LIGHTING - EXTERIOR (Continued)

SPECIFICATIONS - LAMPS/LIGHTING -
EXTERIOR
BULB SPECIFICATIONS
LAMP BULB
Backup 3157 P27/7W
Brake 3157 P27/7W
Center High Mounted
Stop921/W16W
Front Fog 9145
Front Park 3157 P27/7W
Front Position W5W
Front Side Marker 168
Front Turn 3157 P27/7W
Headlamp (North
America)9007QL
Headlamp (Rest-Of-
World)H-4 W0W6
License Plate (North
America)168
License Plate (Rest-Of-
World)W5W
Rear Fog 3157 P27/7W
Rear Park/Tail 3157 P27/7W
Rear Turn 3157 P27/7W
Side Repeater W5W
BACKUP LAMP SWITCH
DESCRIPTION
Vehicles equipped with a manual transmission
have a normally open, spring-loaded plunger type
back-up lamp switch (Fig. 2). The backup lamp
switch is located in a threaded hole on the side of the
manual transmission housing, beneath the floor
panel of the vehicle. The backup lamp switch has a
threaded body and a hex formation near the plunger
end of the switch, and an integral connector recepta-
cle at the opposite end of the switch. When installed,
only the connector receptacle and the hex formation
are visible on the outside of the transmission hous-
ing. Vehicles with an optional electronic automatic
transmission have a Transmission Range Sensor
(TRS) that is used to perform several functions,
including that of the backup lamp switch. The TRS is
described in further detail elsewhere in this service
information. The backup lamp switch cannot be
adjusted or repaired and, if faulty or damaged, the
entire switch unit must be replaced.
OPERATION
The backup lamp switch controls the flow of bat-
tery current to the backup lamp bulbs at the back of
the vehicle through an output on the back-up lamp
feed circuit. The switch plunger is mechanically actu-
ated by the gearshift mechanism within the trans-
mission, which will depress the switch plunger and
close the switch contacts whenever the reverse gear
has been selected. The switch receives battery cur-
rent through a fuse in the Junction Block (JB) on a
fused ignition switch output (run) circuit whenever
the ignition switch is in the On position. A take out
of the engine wire harness connects the backup lamp
switch to the vehicle electrical system. The backup
lamp switch and circuits can be tested using conven-
tional diagnostic tools and methods.
DIAGNOSIS AND TESTING - BACKUP LAMP
SWITCH
(1) Disconnect and isolate the battery negative
cable.
(2) Raise and support the vehicle.
(3) Locate and disconnect the engine wire harness
connector for the backup lamp switch from the
switch connector receptacle.
(4) Check for continuity between the two terminal
pins in the backup lamp switch connector receptacle.
(a) With the gear selector lever in the Reverse
position, there should be continuity.
(b) With the gear selector lever in any position
other than Reverse, there should be no continuity.
Fig. 2 Backup Lamp Switch - Typical
1 - MANUAL TRANSMISSION
2 - BACKUP LAMP SWITCH
3 - ENGINE WIRE HARNESS
KJLAMPS8Ls-15
LAMPS/LIGHTING - EXTERIOR (Continued)

BRAKE LAMP SWITCH
DESCRIPTION
The brake lamp switch is a three circuit, spring-
loaded plunger actuated switch that is secured to the
steering column support bracket under the driver
side of the instrument panel (Fig. 3). The brake lamp
switch is contained within a rectangular molded plas-
tic housing with an integral connector receptacle fea-
turing six terminal pins and a red plastic Connector
Position Assurance (CPA) lock. The switch is con-
nected to the vehicle electrical system through a ded-
icated take out and connector of the instrument
panel wire harness. The switch plunger extends
through a mounting collar on one end of the switch
housing. The plunger has a one time telescoping self-
adjustment feature that is achieved after the switch
is installed by moving an adjustment release lever on
the opposite end of the switch housing clockwise,
until it locks in a position that is parallel to the con-
nector receptacle. The brake lamp switch self-adjust-
ment is a one time feature. Once the feature has
been used, the switch cannot be readjusted. A ªDO
NOT RE-INSTALLº warning is molded into the
switch housing below the connector receptacle.
An installed brake lamp switch cannot be read-
justed or repaired. If the switch is damaged, faulty,
or removed from its mounting position for any rea-
son, it must be replaced with a new unit.
OPERATION
The brake lamp switch controls three different cir-
cuits, one normally open and two normally closed.
These circuits are described as follows:
²Brake Lamp Switch Circuit- A normally
open brake lamp switch circuit receives battery cur-
rent on a fused B(+) circuit from a fuse in the Junc-
tion Block (JB), and supplies battery current to the
brake lamps and the Controller Antilock Brake
(CAB) on a brake lamp switch output circuit when
the brake pedal is depressed (brake lamp switch
plunger released).
²Brake Lamp Switch Signal Circuit- A nor-
mally closed brake lamp switch signal circuit receives
a path to ground through a splice block located in the
instrument panel wire harness with an eyelet termi-
nal connector that is secured by a nut to a ground
stud on the driver side instrument panel end bracket
near the Junction Block (JB). This circuit supplies a
ground input to the Powertrain Control Module
(PCM) on a brake lamp switch sense circuit when the
brake pedal is released (brake lamp switch plunger is
depressed).
²Speed Control Circuit- A normally closed
speed control circuit receives battery current from
the Powertrain Control Module on a speed control
supply circuit, and supplies battery current to the
speed control servo solenoids (dump, vacuum, and
vent) on a speed control brake switch output circuit
when the speed control system is turned on and the
brake pedal is released (brake lamp switch plunger is
depressed).
Concealed within the brake lamp switch housing
the components of the self-adjusting brake switch
plunger consist of a two-piece telescoping plunger, a
split plunger locking collar, and a release wedge. The
release lever has an integral shaft with a wedge that
spreads the plunger locking collar to an open or
released position. After the switch is installed and
the brake pedal is released, the plunger telescopes to
the correct adjustment position. When the release
lever is moved to the release position, the wedge is
disengaged from the locking collar causing the collar
to apply a clamping pressure to the two plunger
halves fixing the plunger length.
The brake lamp switch can be diagnosed using con-
ventional diagnostic tools and methods.
Fig. 3 Brake Lamp Switch
1 - CONNECTOR RECEPTACLE
2 - BRAKE LAMP SWITCH
3 - PLUNGER
4 - COLLAR
5 - LEVER
8Ls - 16 LAMPSKJ

DIAGNOSIS AND TESTING - BRAKE LAMP
SWITCH
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE SUPPLEMENTAL RESTRAINT
SYSTEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, DRIVER AIRBAG,
PASSENGER AIRBAG, SEAT BELT TENSIONER,
FRONT IMPACT SENSORS, SIDE CURTAIN AIRBAG,
OR INSTRUMENT PANEL COMPONENT DIAGNOSIS
OR SERVICE. DISCONNECT AND ISOLATE THE
BATTERY NEGATIVE (GROUND) CABLE, THEN
WAIT TWO MINUTES FOR THE SYSTEM CAPACI-
TOR TO DISCHARGE BEFORE PERFORMING FUR-
THER DIAGNOSIS OR SERVICE. THIS IS THE ONLY
SURE WAY TO DISABLE THE SUPPLEMENTAL
RESTRAINT SYSTEM. FAILURE TO TAKE THE
PROPER PRECAUTIONS COULD RESULT IN ACCI-
DENTAL AIRBAG DEPLOYMENT AND POSSIBLE
PERSONAL INJURY.
(1) Disconnect and isolate the battery negative
cable. Disconnect the instrument panel wire harness
connector for the brake lamp switch from the switch
connector receptacle.
(2) Using an ohmmeter, perform the continuity
tests at the terminal pins in the brake lamp switch
connector receptacle (Fig. 4) as shown in the Brake
Lamp Switch Tests table.
BRAKE LAMP SWITCH TESTS
PLUNGER POSITION CONTINUITY BETWEEN
Released (Extended) Pins1&2
Compressed (Retracted) Pins3&4,5&6
(3) If the switch fails any of the continuity tests,
replace the faulty brake lamp switch as required.
REMOVAL
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE SUPPLEMENTAL RESTRAINT
SYSTEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, DRIVER AIRBAG,
PASSENGER AIRBAG, SEAT BELT TENSIONER,
FRONT IMPACT SENSORS, SIDE CURTAIN AIRBAG,
OR INSTRUMENT PANEL COMPONENT DIAGNOSIS
OR SERVICE. DISCONNECT AND ISOLATE THE
BATTERY NEGATIVE (GROUND) CABLE, THEN
WAIT TWO MINUTES FOR THE SYSTEM CAPACI-
TOR TO DISCHARGE BEFORE PERFORMING FUR-
THER DIAGNOSIS OR SERVICE. THIS IS THE ONLY
SURE WAY TO DISABLE THE SUPPLEMENTAL
RESTRAINT SYSTEM. FAILURE TO TAKE THE
PROPER PRECAUTIONS COULD RESULT IN ACCI-
DENTAL AIRBAG DEPLOYMENT AND POSSIBLE
PERSONAL INJURY.
(1) Disconnect and isolate the battery negative
cable.
(2) Disconnect the instrument panel wire harness
connector for the brake lamp switch from the switch
connector receptacle (Fig. 5).
(3) Grasp the brake lamp switch housing firmly
and rotate the switch counterclockwise about 30
degrees to align the tabs on the locking collar with
the keyed mounting hole in the steering column sup-
port bracket.
(4) Pull the switch straight back from the mount-
ing hole to remove it from the steering column sup-
port bracket.
(5) Discard the removed brake lamp switch.
Fig. 4 Brake Lamp Switch Terminal Identification
1 - TERMINAL PINS
2 - PLUNGER TEST POSITIONS
Fig. 5 Brake Lamp Switch Remove/Install
1 - STEERING COLUMN SUPPORT
2 - WIRE HARNESS CONNECTOR
3 - LEVER
4 - BRAKE LAMP SWITCH
5 - BRAKE PEDAL ARM
KJLAMPS8Ls-17
BRAKE LAMP SWITCH (Continued)

CAUTION: Always replace a removed brake lamp
switch with a new unit. This is a one time compo-
nent and is not intended for reinstallation.
INSTALLATION
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE SUPPLEMENTAL RESTRAINT
SYSTEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, DRIVER AIRBAG,
PASSENGER AIRBAG, SEAT BELT TENSIONER,
FRONT IMPACT SENSORS, SIDE CURTAIN AIRBAG,
OR INSTRUMENT PANEL COMPONENT DIAGNOSIS
OR SERVICE. DISCONNECT AND ISOLATE THE
BATTERY NEGATIVE (GROUND) CABLE, THEN
WAIT TWO MINUTES FOR THE SYSTEM CAPACI-
TOR TO DISCHARGE BEFORE PERFORMING FUR-
THER DIAGNOSIS OR SERVICE. THIS IS THE ONLY
SURE WAY TO DISABLE THE SUPPLEMENTAL
RESTRAINT SYSTEM. FAILURE TO TAKE THE
PROPER PRECAUTIONS COULD RESULT IN ACCI-
DENTAL AIRBAG DEPLOYMENT AND POSSIBLE
PERSONAL INJURY.
CAUTION: Always replace a removed brake lamp
switch with a new unit. This is a one time compo-
nent and is not intended for reinstallation.
(1) While holding the brake pedal depressed, align
the tabs on the brake lamp switch locking collar with
the keyed mounting hole in the steering column sup-
port bracket (Fig. 5).
(2) Still holding the brake pedal depressed, insert
the tabs on the brake lamp switch housing through
the keyed mounting hole in the steering column sup-
port bracket until the switch is firmly seated against
the bracket.
(3) Still holding the brake pedal depressed, rotate
the switch clockwise about 30 degrees to lock the
tabs on the brake lamp switch locking collar to the
keyed mounting hole in the steering column support
bracket.
(4) Release the brake pedal.
CAUTION: Do not pull up on the brake pedal before
the switch plunger adjustment has been completed.
(5) Rotate the plunger adjustment release lever
clockwise until it locks into place parallel to the
brake lamp switch connector receptacle. This action
will set the switch plunger length to a final adjust-
ment position and cannot be undone. If not per-
formed properly the first time, a new brake lamp
switchmustbe installed.(6) Reconnect the instrument panel wire harness
connector for the brake lamp switch to the switch
connector receptacle.
(7) Reconnect the battery negative cable.
CENTER HIGH MOUNTED
STOP LAMP BULB
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the Center High Mounted Stop Lamp
(CHMSL) unit from the roof panel. (Refer to 8 -
ELECTRICAL/LAMPS/LIGHTING - EXTERIOR/
CENTER HIGH MOUNTED STOP LAMP UNIT -
REMOVAL).
(3) Firmly grasp the socket on the back of the
CHMSL unit housing.
(4) Rotate the socket on the back of the CHMSL
unit housing counterclockwise about 30 degrees (Fig.
6).
(5) Pull the socket and bulb straight out of the
back of CHMSL unit housing.
(6) Pull the bulb straight out of the CHMSL unit
socket.
Fig. 6 Center High Mounted Stop Lamp Bulb
Remove/Install
1 - CHMSL UNIT
2 - BULB
3 - SOCKET
4 - BODY WIRE HARNESS CONNECTOR
8Ls - 18 LAMPSKJ
BRAKE LAMP SWITCH (Continued)

INSTALLATION
CAUTION: Always use the correct bulb size and
type for replacement. An incorrect bulb size or type
may overheat and cause damage to the lamp, the
socket and/or the lamp wiring.
(1) Align the base of the bulb with the receptacle
in the Center High Mounted Stop Lamp (CHMSL)
unit socket.
(2) Push the bulb straight into the CHMSL unit
socket until it is firmly seated.
(3) Align the socket and bulb with the socket open-
ing on the back of CHMSL unit housing.
(4) Push the socket and bulb straight into the
CHMSL unit housing until it is firmly seated (Fig. 6).
(5) Rotate the socket on the back of the CHMSL
unit housing clockwise about 30 degrees.
(6) Reinstall the CHMSL unit onto the roof panel.
(Refer to 8 - ELECTRICAL/LAMPS/LIGHTING -
EXTERIOR/CENTER HIGH MOUNTED STOP
LAMP UNIT - INSTALLATION).
(7) Reconnect the battery negative cable.
CENTER HIGH MOUNTED
STOP LAMP UNIT
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the two screws that secure the Center
High Mounted Stop Lamp (CHMSL) unit to the rear
of the roof panel (Fig. 7).
(3) Pull the CHMSL unit away from the roof panel
far enough to access and disconnect the wire harness
connector for the CHMSL unit from the lamp socket
pigtail wire.
(4) Remove the CHMSL unit from the roof panel.
INSTALLATION
(1) Position the Center High Mounted Stop Lamp
(CHMSL) unit to the roof panel.
(2) Reconnect the wire harness connector for the
CHMSL unit to the lamp socket pigtail wire (Fig. 7).
(3) Position the CHMSL unit into the roof panel
opening.
(4) Install and tighten the two screws that secure
the CHMSL unit to the rear of the roof panel.
Tighten the screws to 2 N´m (21 in. lbs.).
(5) Reconnect the battery negative cable.
COMBINATION FLASHER
DESCRIPTION
The combination flasher for this model is integral
to the hazard switch located in the center of the
instrument panel, just above the radio. The combina-
tion flasher is a smart relay that functions as both
the turn signal system and the hazard warning sys-
tem flasher. The combination flasher contains active
electronic Integrated Circuitry (IC) elements. This
flasher is designed to handle the current flow
requirements of the factory-installed lighting. If sup-
plemental lighting is added to the turn signal lamp
circuits, such as when towing a trailer with lights,
the combination flasher will automatically try to
compensate to keep the flash rate the same.
The combination flasher cannot be repaired or
adjusted and, if faulty or damaged, the hazard switch
unit must be replaced.
OPERATION
The combination flasher has the following inputs and
outputs: fused B(+), fused ignition switch output, right
turn signal sense, left turn signal sense, and one out-
put each for the right and left turn signal circuits. The
combination flasher also receives an internal input
through the closed contacts of the hazard switch and,
on vehicles equipped with the optional Vehicle Theft
Security System (VTSS), the flasher receives an input
from the Body Control Module (BCM) in order to flash
the turn signal lamps as an optical alert feature of that
Fig. 7 Center High Mounted Stop Lamp Remove/
Install
1 - ROOF PANEL
2 - BODY WIRE HARNESS CONNECTOR
3 - BULB SOCKET
4 - CHMSL
5 - SCREW (2)
6 - PLASTIC NUT (2)
KJLAMPS8Ls-19
CENTER HIGH MOUNTED STOP LAMP BULB (Continued)