2002 JEEP LIBERTY Workshop Manual

reliable, efficient, and accurate means to diagnose
the BCM, the EMIC, the PCM, and the PCI data bus
network inputs and outputs related to the various
exterior lighting systems requires the use of a
DRBIIItscan tool. Refer to the appropriate diagnos-
tic information.
When diagnosing the exterior lighting circuits,
remember that high generator output can burn out
bulbs rapidly and repeatedly; and, that dim or flick-
ering bulbs can be caused by low generator output or
poor battery condition. If one of these symptoms is a
problem on the vehicle being diagnosed, be certain to
diagnose and repair the battery and charging system
as required. Also keep in mind that a good ground is
necessary for proper lighting operation. If a lighting
problem is being diagnosed that involves multiple
symptoms, systems, or components the problem can
often be traced to a loose, corroded, or open ground.
For complete circuit diagrams, refer to the appropri-
ate wiring information. The wiring information
includes wiring diagrams, proper wire and connectorrepair procedures, details of wire harness routing
and retention, connector pin-out information and
location views for the various wire harness connec-
tors, splices and grounds.
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.
BACKUP LAMPS
CONDITION POSSIBLE CAUSES CORRECTION
BACKUP LAMP DOES
NOT ILLUMINATE1. Faulty or missing fuse. 1. Test and replace backup lamp fuse as
required.
2. Faulty or missing bulb. 2. Test and replace backup lamp bulb as
required.
3. Faulty switch. 3. Test and replace backup lamp switch
(manual transmission) or transmission
range sensor (automatic transmission) as
required.
4. Faulty ground circuit. 4. Test and repair backup lamp ground
circuit as required.
5. Faulty feed circuit. 5. Test and repair open back-up lamp feed
circuit as required.
BACKUP LAMP DOES
NOT EXTINGUISH1. Faulty switch. 1. Test and replace backup lamp switch
(manual transmission) or transmission
range sensor (automatic transmission) as
required.
2. Faulty feed circuit. 2. Test and repair shorted back-up lamp
feed circuit as required.
8L - 8 LAMPS/LIGHTING - EXTERIORKJ
LAMPS/LIGHTING - EXTERIOR (Continued)

BRAKE LAMPS
CONDITION POSSIBLE CAUSES CORRECTION
BRAKE LAMP DOES NOT
ILLUMINATE1. Faulty or missing fuse. 1. Test and replace brake lamp fuse as
required.
2. Faulty or missing bulb. 2. Test and replace brake lamp bulb as
required.
3. Faulty switch. 3. Test and replace brake lamp switch as
required.
4. Faulty ground circuit. 4. Test and repair brake lamp ground circuit
as required.
5. Faulty feed circuit. 5. Test and repair open brake lamp switch
output circuit as required.
BRAKE LAMP DOES NOT
EXTINGUISH1. Faulty switch. 1. Test and replace brake lamp switch as
required.
2. Faulty feed circuit. 2. Test and repair shorted brake lamp
switch output circuit as required.
DAYTIME RUNNING LAMPS
Before performing the following tests, determine
whether the headlamp low and high beams operate.If the headlamp high and low beams are also inoper-
ative, diagnose and repair that problem before
attempting to repair the Daytime Running Lamps.
CONDITION POSSIBLE CAUSES CORRECTION
DAYTIME RUNNING
LAMPS WILL NOT
ILLUMINATE1. High beam relay installed. 1. Remove high beam relay as required.
2. Faulty or missing DRL relay. 2. Replace DRL relay with a known good
unit and check operation. Replace DRL
relay as required.
3. Incorrect BCM programming. 3. Use a DRBIIITscan tool to check and
program correct country code into BCM as
required.
4. Faulty BCM inputs or outputs. 4. Use a DRBIIITscan tool to test the BCM
inputs or outputs. Refer to the appropriate
diagnostic information.
KJLAMPS/LIGHTING - EXTERIOR 8L - 9
LAMPS/LIGHTING - EXTERIOR (Continued)

FRONT FOG LAMPS
CONDITION POSSIBLE CAUSES CORRECTION
FRONT FOG LAMP DOES
NOT ILLUMINATE1. Faulty or missing fuse. 1. Test and replace front fog lamp fuse as
required.
2. Faulty or missing bulb. 2. Test and replace front fog lamp bulb as
required.
3. Faulty or missing relay. 3. Test and replace front 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 front fog lamp ground
circuit as required.
6. Faulty feed circuit. 6. Test and repair open front 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.
FRONT FOG LAMP DOES
NOT EXTINGUISH1. Faulty relay. 1. Test and replace front 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 front 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.
HAZARD WARNING LAMPS
Before performing the following tests, confirm
whether the left and right turn signals operate satis-
factorily. If the turn signals are inoperative or oper-ate improperly, diagnose and repair that problem
before attempting to repair the Hazard Warning
Lamps.
CONDITION POSSIBLE CAUSES CORRECTION
HAZARD WARNING
LAMPS DO NOT FLASH1. Faulty or missing fuse. 1. Test and replace hazard warning fuse as
required.
2. Faulty ground circuit. 2. Test and repair hazard switch ground
circuit as required.
3. Faulty feed circuit. 3. Test and repair open hazard switch fused
B(+) circuit as required.
4. Faulty switch/flasher. 4. Replace hazard switch/combination
flasher with a known good unit and check
operation. Replace hazard switch/
combination flasher unit if required.
8L - 10 LAMPS/LIGHTING - EXTERIORKJ
LAMPS/LIGHTING - EXTERIOR (Continued)

HEADLAMPS
CONDITION POSSIBLE CAUSES CORRECTION
HEADLAMP DOES NOT
ILLUMINATE1. Faulty or missing fuse. 1. Test and replace headlamp fuse as
required.
2. Faulty or missing bulb. 2. Test and replace headlamp bulb as
required.
3. Faulty or missing relay. 3. 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.)
4. Faulty switch. 4. Test and replace multi-function switch as
required.
5. Faulty ground circuit. 5. Test and repair open headlamp ground
circuit as required.
6. Faulty feed circuit. 6. Test and repair open headlamp low beam,
high beam, or DRL 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.
HEADLAMP DOES NOT
EXTINGUISH1. 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 feed circuit. 3. Test and repair shorted headlamp low
beam, high beam, or DRL 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.
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.
KJLAMPS/LIGHTING - EXTERIOR 8L - 11
LAMPS/LIGHTING - EXTERIOR (Continued)

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.
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.
8L - 12 LAMPS/LIGHTING - EXTERIORKJ
LAMPS/LIGHTING - EXTERIOR (Continued)

CONDITION POSSIBLE CAUSES CORRECTION
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.
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.
KJLAMPS/LIGHTING - EXTERIOR 8L - 13
LAMPS/LIGHTING - EXTERIOR (Continued)

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.
8L - 14 LAMPS/LIGHTING - EXTERIORKJ
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
KJLAMPS/LIGHTING - EXTERIOR 8L - 15
LAMPS/LIGHTING - EXTERIOR (Continued)