2002 JEEP LIBERTY Ignition control

path to the switches using another internal driver
through the courtesy lamp load shed circuit. The
BCM provides a battery saver (load shedding) feature
for all courtesy lamps, which will automatically turn
these lamps off if they are left on for more than
about eight minutes with the ignition switch in the
Off position.
PANEL LAMPS DIMMER CIRCUIT The panel
lamps dimmer circuit includes the ElectroMechanical
Instrument Cluster (EMIC), heater-air conditioner
control, hazard switch and, depending upon the
selected vehicle options, ash receiver, and automatic
transmission range indicator illumination lamps. All
lamps in the panel lamps dimmer circuit are pro-
vided a path to ground at all times through a hard
wired ground circuit. These lamps illuminate based
upon inputs to the Body Control Module (BCM) from
the exterior lighting control knob and the interior
lighting control ring on the left (lighting) control
stalk of the multi-function switch. The control knob
on the left control stalk of the multi-function switch
selects the exterior lights, while the control ring
selects the panel lamps intensity (dimming) level.
When the exterior lighting is turned On, the BCM
energizes the park lamp relay and provides an elec-
tronic dimming level message to the ElectroMechani-
cal Instrument Cluster (EMIC), the radio, and the
Compass Mini-Trip Computer (CMTC) over the Pro-
grammable Communications Interface (PCI) data
bus. The energized park lamp relay provides a hard
wired battery current signal input to the EMIC on
the park lamp relay output circuit. The EMIC
responds to these inputs by supplying a 12-volt Pulse
Width Modulated (PWM) output to all of the incan-
descent lamps in the panel lamps dimmer circuit
over the fused panel lamps dimmer switch signal cir-
cuit. This shared PWM output synchronizes the
selected illumination intensity level of all of the
incandescent lamps in the panel lamps dimmer cir-
cuit.
The EMIC and the radio each use the electronic
dimming level message from the BCM to control and
synchronize the illumination intensity of their own
Vacuum Fluorescent Display (VFD), while the CMTC
uses the dimming level message to control the illumi-
nation intensity of both its VFD and its incandescent
lighting. In addition, when the control ring on the
left (lighting) control stalk of the multi-function
switch is moved to the Parade Mode detent position,
all of the VFDs are illuminated at their full intensity
levels for increased visibility when the vehicle is
driven during daylight hours with the exterior lights
turned On.DIAGNOSIS AND TESTING - LAMPS/LIGHTING
- INTERIOR
The hard wired circuits and components of the
interior lighting system may be diagnosed and tested
using conventional diagnostic tools and procedures.
However, conventional diagnostic methods may not
prove conclusive in the diagnosis of the Body Control
Module (BCM), the ElectroMechanical Instrument
Cluster (EMIC), or the Programmable Communica-
tions Interface (PCI) data bus network. The most
reliable, efficient, and accurate means to diagnose
the BCM, the EMIC, and the PCI data bus network
inputs and outputs related to the various interior
lighting systems requires the use of a DRBIIItscan
tool. Refer to the appropriate diagnostic information.
When diagnosing the interior 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 connector
repair 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.
8L - 68 LAMPS/LIGHTING - INTERIORKJ
LAMPS/LIGHTING - INTERIOR (Continued)

²Trailer Tow Adapter- Vehicles equipped with
a factory-installed trailer towing package have an
adapter provided that adapts the factory-installed
heavy duty 7-way trailer tow connector to a conven-
tional 4-way light duty connector.
²Trailer Tow Connector- Vehicles equipped
with a factory-installed trailer towing package have a
heavy duty 7-way trailer tow connector installed in a
bracket on the trailer hitch receiver.
²Trailer Tow Relays- Vehicles equipped with a
factory-installed trailer towing package have a con-
nector bank containing four relays located behind the
right quarter trim panel and over the right rear
wheel housing. The four relays are used to supply
fused ignition switch output (run), brake lamps, right
turn signal, and left turn signal outputs to a trailer
through the trailer tow wiring and connectors.
Hard wired circuitry connects the exterior lighting
system components to the electrical system of the
vehicle. These hard wired circuits are integral to sev-
eral 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 exterior lighting
system components through the use of a combination
of soldered splices, splice block connectors, and many
different types of wire harness terminal connectors
and insulators. Refer to the appropriate wiring infor-
mation. The wiring information includes wiring dia-
grams, proper wire and connector repair procedures,
further details on wire harness routing and reten-
tion, as well as pin-out and location views for the
various wire harness connectors, splices and grounds.
OPERATION
Following are paragraphs that briefly describe the
operation of each of the major exterior lighting sys-
tems. The hard wired circuits and components of the
exterior lighting systems may be diagnosed and
tested using conventional diagnostic tools and proce-
dures. However, conventional diagnostic methods
may not prove conclusive in the diagnosis of the Body
Control Module (BCM), the ElectroMechanical
Instrument Cluster (EMIC), the Powertrain Control
Module (PCM), or the Programmable Communica-
tions Interface (PCI) data bus network. The most
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.BACKUP LAMPS
The backup (or reverse) lamps have a path to
ground at all times through their connection to the
rear lighting wire harness from a take out of the rear
body wire harness with an eyelet terminal connector
that is secured by a ground screw to the base of the
right D-pillar behind the quarter trim panel. The
backup lamps receive battery current from a fused
ignition switch output (run) fuse in the Junction
Block (JB) on the back-up lamp feed circuit only
when the backup lamp switch (manual transmission),
or backup lamp switch circuit of the Transmission
Range Sensor (TRS - electronic automatic transmis-
sion) is closed by the gearshift mechanism within the
transmission.
BRAKE LAMPS
The brake (or stop) lamps have a path to ground at
all times through their connection to the rear light-
ing wire harness from a take out of the rear body
wire harness with an eyelet terminal connector that
is secured by a screw to the base of the right D-pillar
behind the quarter trim panel. The Center High
Mounted Stop Lamp (CHMSL) has a path to ground
at all times through its connection to the rear body
wire harness from a take out of the rear body wire
harness with an eyelet terminal connector that is
secured by a ground screw to the driver side D-pillar
(left side D-pillar for left-hand drive, right side D-pil-
lar for right-hand drive) behind the quarter trim
panel. The brake lamps and CHMSL receive battery
current from a fused B(+) fuse in the Junction Block
(JB) on the brake lamp switch output circuit only
when the brake lamp switch circuit of the brake
lamp switch is closed by the brake pedal arm.
DAYTIME RUNNING LAMPS
Vehicles manufactured for sale in Canada illumi-
nate the high beam filament at a reduced intensity
when the engine is running and the exterior lamps
are turned off. This feature is enabled by the Body
Control Module (BCM) and a solid state Daytime
Running Lamps (DRL) relay, which is installed in the
Junction Block (JB) and the high beam relay is omit-
ted. When the BCM monitors an engine speed signal
of greater than 450 RPM and the status of the exte-
rior lighting switch input from the multi-function
switch is Off, the BCM duty cycles the DRL relay to
produce illumination of the headlamp high beam fil-
aments at a reduced intensity. The BCM also pro-
vides normal headlamp high beam operation through
the DRL relay on vehicles so equipped. When the
DRL relay is energized, it provides battery current
from a fused B(+) fuse in the JB to the headlamp
high beam filament through the DRL relay output
circuit.
KJLAMPS8Ls-5
LAMPS/LIGHTING - EXTERIOR (Continued)

FRONT FOG LAMPS
Vehicles equipped with optional front fog lamps
have a premium Body Control Module (BCM), a front
fog lamp relay installed in the Junction Block (JB),
and a front fog lamp switch integral to the left (light-
ing) control stalk of the multi-function switch. The
front fog lamps have a path to ground at all times
through their connection to the front fascia wire har-
ness from two take outs of the headlamp and dash
wire harness with eyelet terminal connectors that
are secured by ground screws to the left inner fender
shield in the engine compartment. The BCM controls
front fog lamp operation by monitoring the exterior
lighting switch input from the multi-function switch,
then energizing or de-energizing the front fog lamp
relay control coil; and, by sending the appropriate
electronic message to the instrument cluster over the
Programmable Communications Interface (PCI) data
bus to turn the front fog lamp indicator on or off.
When the front fog lamp relay is energized, it pro-
vides battery current from a fused B(+) fuse in the
JB to the front fog lamps through the front fog lamp
relay output circuit. The BCM provides a battery
saver (load shedding) feature for the front fog lamps,
which will turn these lamps off if they are left on for
more than about eight minutes with the ignition
switch in the Off position. In certain markets where
required, the front fog lamps are also turned off by
the BCM whenever the headlamp high beams are
selected. Each front fog lamp includes an integral
adjustment screw to be used for static aiming the fog
lamp beams.
HAZARD WARNING LAMPS
With the hazard switch in the On position, the
hazard warning system is activated causing the haz-
ard switch button illumination lamp, the right and
left turn signal indicators, and the right and left turn
signal lamps to flash on and off. When the hazard
warning system is activated, the circuitry within the
hazard switch and electronic combination flasher
unit will repeatedly energize and de-energize two
internal relays that switch battery current from a
fused B(+) fuse in the Junction Block (JB) to the
right side and left side turn signal indicators, and
turn signal lamps through the right and left turn sig-
nal circuits. The flashing of the hazard switch button
illumination lamp is performed internally by the haz-
ard switch and combination flasher unit circuit
board. The hazard warning lamps can also be ener-
gized by the Body Control Module (BCM) through a
hazard lamp control circuit input to the hazard
switch and combination flasher unit.HEADLAMPS
The headlamp system includes the Body Control
Module (BCM), a low beam relay installed in the
Junction Block (JB), a high beam relay installed in
the JB (except Canada), a solid state Daytime Run-
ning Lamps (DRL) relay installed in the JB (Canada
only), and the exterior lighting (headlamp and dim-
mer) switches integral to the left (lighting) control
stalk of the multi-function switch. The headlamp
bulbs have a path to ground at all times through
their connection to the grille opening reinforcement
wire harness from two take outs of the headlamp and
dash wire harness with eyelet terminal connectors
that are secured by ground screws to the left inner
fender shield in the engine compartment. The BCM
controls the headlamp operation by monitoring the
exterior lighting switch inputs from the multi-func-
tion switch, then energizing or de-energizing the con-
trol coils of the low beam relay, the high beam relay,
or the solid state circuitry of the DRL relay; and, by
sending the appropriate electronic message to the
instrument cluster over the Programmable Commu-
nications Interface (PCI) data bus to turn the high
beam indicator on or off. When each respective relay
is energized, it provides battery current from a fused
B(+) fuse in the Power Distribution Center (PDC)
through a relay (low beam, high beam, or DRL) out-
put circuit and four separate fuses in the JB through
individual fused right and left, low and high beam
output circuits to the appropriate headlamp bulb fil-
aments. The BCM provides a battery saver (load
shedding) feature for the headlamps, which will turn
these lamps off if they are left on for more than
about eight minutes with the ignition switch in the
Off position; and, a headlamp delay feature with a
DRBIIItscan tool programmable delay interval.
Each headlamp includes an integral adjustment
screw to be used for static aiming of the headlamp
beams.
HEADLAMP LEVELING
In certain markets where required, a headlamp
leveling system is provided on the vehicle. The head-
lamp leveling system includes unique headlamp units
equipped with a headlamp leveling actuator motor,
and a rotary thumbwheel actuated headlamp leveling
switch on the instrument panel. The headlamp level-
ing system allows the headlamp beams to be
adjusted to one of four vertical positions to compen-
sate for changes in inclination caused by the loading
of the vehicle suspension. The actuator motors are
mechanically connected through an integral pushrod
to an adjustable headlamp reflector. The headlamp
leveling switch is a resistor multiplexed unit that
provides one of four voltage outputs to the headlamp
leveling motors. The headlamp leveling motors will
8Ls - 6 LAMPSKJ
LAMPS/LIGHTING - EXTERIOR (Continued)

move the headlamps to the selected position based
upon the voltage input received from the switch. The
headlamp leveling motors and switch have a path to
ground at all times. The headlamp leveling compo-
nents operate on battery current received through
the fused park lamp relay output circuit so that the
system will only operate when the exterior lighting is
turned on.
PARK LAMPS
The park lamps system includes the Body Control
Module (BCM), a park lamp relay installed in the
Junction Block (JB), and the exterior lighting switch
integral to the left (lighting) control stalk of the
multi-function switch. The front park lamp and side
marker or, if equipped, the front position lamp bulbs
each have a path to ground at all times through their
connections to the grille opening reinforcement wire
harness from two take outs of the headlamp and
dash wire harness with eyelet terminal connectors
that are secured by ground screws to the left inner
fender shield in the engine compartment. The rear
park lamp bulbs and license plate lamp have a path
to ground at all times through their connection to the
rear lighting wire harness from a take out of the rear
body wire harness with an eyelet terminal connector
that is secured by a ground screw to the base of the
right D-pillar behind the quarter trim panel. The
BCM controls the park lamp operation by monitoring
the exterior lighting switch inputs from the multi-
function switch, then energizing or de-energizing the
control coil of the park lamp relay. When the park
lamp relay is energized, it provides battery current
from a fused B(+) fuse in the Power Distribution
Center (PDC) through a park lamp relay output cir-
cuit and a separate fuse in the JB through a fused
park lamp relay output circuit to the appropriate
lamp bulb filaments. The BCM provides a battery
saver (load shedding) feature for the park lamps,
which will turn these lamps off if they are left on for
more than about eight minutes with the ignition
switch in the Off position.
REAR FOG LAMPS
Rear fog lamps are installed on vehicles manufac-
tured for certain markets where they are required.
The rear fog lamp system includes a premium Body
Control Module (BCM), a rear fog lamp relay
installed in the Junction Block (JB), and a rear fog
lamp switch integral to the left (lighting) control
stalk of the multi-function switch. The rear fog lamps
have a path to ground at all times through their con-
nection to the rear lighting wire harness from a take
out of the rear body wire harness with an eyelet ter-
minal connector that is secured by a ground screw to
the base of the right D-pillar behind the quarter trimpanel. The BCM controls rear fog lamp operation by
monitoring the exterior lighting switch input from
the multi-function switch, then energizing or de-ener-
gizing the rear fog lamp relay control coil; and, by
sending the appropriate electronic message to the
instrument cluster over the Programmable Commu-
nications Interface (PCI) data bus to turn the rear
fog lamp indicator on or off. When the rear fog lamp
relay is energized, it provides battery current from a
fused B(+) fuse in the JB to the rear fog lamps
through the rear fog lamp relay output circuit. The
BCM provides a battery saver (load shedding) feature
for the rear fog lamps, which will turn these lamps
off if they are left on for more than about eight min-
utes with the ignition switch in the Off position.
TURN SIGNAL LAMPS
When the left control stalk of the multi-function
switch is moved up (right turn) or down (left turn),
the turn signal system is activated causing the
selected right or left turn signal indicator, and right
or left turn signal lamps to flash on and off. When
the turn signal system is activated, the circuitry
within the turn signal switch and the hazard switch/
electronic combination flasher unit will repeatedly
energize and de-energize one of two internal relays
that switch battery current from a fused ignition
switch output (run) fuse in the Junction Block (JB) to
the right side or left side turn signal indicators and
turn signal lamps through the right or left turn sig-
nal circuits. The ElectroMechanical Instrument Clus-
ter (EMIC) chime tone generator will generate an
audible turn signal cancel warning each time the
vehicle is driven for a distance of about 3.2 kilome-
ters (about two miles) with a turn signal indicator
flashing. The EMIC uses Programmable Communica-
tions Interface (PCI) data bus distance messages
from the Powertrain Control Module (PCM) and a
hard wired input from the turn signal switch cir-
cuitry of the multi-function switch to determine when
to sound the turn signal cancel warning.
DIAGNOSIS AND TESTING - LAMPS/LIGHTING
- EXTERIOR
The hard wired circuits and components of the
exterior lighting systems may be diagnosed and
tested using conventional diagnostic tools and proce-
dures. However, conventional diagnostic methods
may not prove conclusive in the diagnosis of the Body
Control Module (BCM), the ElectroMechanical
Instrument Cluster (EMIC), the Powertrain Control
Module (PCM), or the Programmable Communica-
tions Interface (PCI) data bus network. The most
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
KJLAMPS8Ls-7
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)

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)

system. Constant battery voltage is supplied to the
flasher so that it can perform the hazard warning func-
tion, and ignition switched battery voltage is supplied
for the turn signal function. The Integrated Circuit (IC)
within the combination flasher contains the logic that
controls the flasher operation and the flash rate. The
IC receives separate sense ground inputs from the
multi-function switch for the right and left turn sig-
nals, and from the hazard switch contacts or the BCM
for the hazard warning signals. A special design feature
of the combination flasher allows it to9sense9that a
turn signal circuit or bulb is not operating, and provide
the driver an indication of the condition by flashing the
remaining bulbs in the affected circuit at a higher rate
(120 flashes-per-minute or higher). Conventional flash-
ers either continue flashing at their typical rate (heavy-
duty type), or discontinue flashing the affected circuit
entirely (standard-duty type).
Because of the active electronic elements within
the combination flasher, it cannot be tested with con-
ventional automotive electrical test equipment. If the
combination flasher is believed to be faulty, test the
turn signal and hazard warning system. Then
replace the hazard switch with a known good unit to
confirm system operation.
DAYTIME RUNNING LAMP
RELAY
DESCRIPTION
The Daytime Running Lamp (DRL) relay (Fig. 8) is
a solid state relay that is used only on vehicles man-
ufactured for sale in Canada. The DRL relay featuresa die cast aluminum housing with integral cooling
fins that act as a heat sink for the solid state DRL
circuitry. Four male spade terminals extend from the
base of the relay through a potting material that
encloses and protects the DRL circuitry. Although the
DRL relay has four terminals that are laid out in a
footprint that is similar to that of a conventional
International Standards Organization (ISO) relay, a
standard ISO relay should never be installed in place
of the DRL relay. The DRL relay is installed in the
Junction Block (JB) on the driver side outboard end
of the instrument panel. Vehicles equipped with this
relay do not have a headlamp high beam relay
installed in the JB.
The DRL relay cannot be adjusted or repaired and,
if faulty or damaged, the unit must be replaced.
OPERATION
The Daytime Running Lamp (DRL) relay is a solid
state relay that controls the flow of battery current
to the high beam filaments of both headlamp bulbs
based upon a duty cycled control input received from
the Body Control Module (BCM) of vehicles equipped
with the DRL feature. By cycling the DRL relay out-
put, the BCM controls the illumination intensity of
the high beam filaments. The DRL relay terminals
are connected to the vehicle electrical system through
a connector receptacle in the Junction Block (JB).
The inputs and outputs of the DRL relay include:
²Battery Current Input- The DRL relay
receives battery current on a fused B(+) circuit from
a fuse in the Power Distribution Center (PDC).
²Ground Input- The DRL relay 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).
²Control Input- The DRL relay control input is
received from the BCM and/or the momentary optical
horn (flash-to-pass) output of the multi-function
switch through a high beam relay control circuit.
²Control Output- The DRL relay supplies bat-
tery current output to the headlamp high beam fila-
ments through the high beam relay output circuit.
Because of active electronic elements within the
DRL relay, it cannot be tested with conventional
automotive electrical test equipment. If the DRL
relay is believed to be faulty, replace the relay with a
known good unit to confirm system operation.
Fig. 8 Daytime Running Lamp Relay
1 - DRL RELAY
2 - HEAT SINK
3 - POTTING MATERIAL
4 - TERMINAL (4)
8Ls - 20 LAMPSKJ
COMBINATION FLASHER (Continued)

switch module housing is the hazard switch circuitry
and an electronic circuit board with the integral com-
bination flasher circuitry. The electronic combination
flasher circuitry performs both the hazard flasher
and turn signal flasher functions.
The hazard switch module cannot be adjusted or
repaired and, if faulty or damaged, the unit must be
replaced.
OPERATION
The hazard switch button is slightly recessed in
the instrument panel when the switch is in the Off
position, and latches at a position that is flush with
the outer surface of the instrument panel when in
the On position. The hazard switch module produces
an audible clicking sound that emulates the sound of
a conventional flasher whenever the turn signals or
the hazard warning system are activated. The hazard
switch module receives battery current on a fused
B(+) circuit from a fuse in the Junction Block (JB) at
all times for operation of the hazard warning, and on
a fused ignition switch output (run) circuit from
another fuse in the JB whenever the ignition switch
is in the On position for operation of the turn signals.
The module receives a path to ground through a
splice block located in the instrument panel wire har-
ness with an eyelet terminal connector that is
secured by a nut to a ground stud on the driver side
instrument panel end bracket near the JB. Inputs to
and outputs from the hazard switch module include:
²Panel Lamps Dimmer Input- A non-service-
able incandescent bulb soldered onto the hazard
switch module circuit board provides illumination of
the switch button when the exterior lighting is
turned On through an input received on the fusedpanel lamps dimmer switch signal circuit. However,
this bulb flashes on and off at full intensity whenever
the hazard switch button is in the On position,
regardless of the status of the exterior lighting.
²Hazard Switch Input- The combination
flasher circuitry of the hazard switch module receives
an internal ground input from the hazard switch to
request hazard flasher operation.
²Multi-Function Switch Input- The combina-
tion flasher circuitry of the hazard switch module
receives separate ground inputs from the turn signal
switch circuitry of the multi-function switch on right
and left turn switch sense circuits to request right or
left turn signal flasher operation.
²Body Control Module Input- The Body Con-
trol Module (BCM) can request hazard flasher opera-
tion by providing a ground path to the combination
flasher circuitry of the hazard switch module through
a hazard lamp control circuit.
²Turn Signal Output- The combination flasher
circuitry within the hazard switch module responds
to the flasher request inputs by energizing and
de-energizing two miniature relays on the module
circuit board. These relays control the switch output
through the right and left turn signal circuits. One
relay controls the right lamps, while the other con-
trols the left.
Because of active electronic elements within the
hazard switch module, it cannot be tested with con-
ventional automotive electrical test equipment. If the
hazard switch module is believed to be faulty, replace
the switch with a known good unit to confirm system
operation.
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.
Fig. 21 Hazard Switch
1 - HAZARD SWITCH BUTTON
2 - SCREW (1)
3 - MOUNTING BRACKET TABS
KJLAMPS8Ls-29
HAZARD SWITCH (Continued)