Jeep Cherokee (XJ): Description and operation
DESCRIPTION The instrument panel serves as the command center
of the vehicle, which necessarily makes it a very
complex unit. The instrument panel is designed to
house the controls and monitors for standard and
optional powertrains, climate control systems, audio
systems, lighting systems, safety systems and many
other comfort or convenience items. The instrument
panel is also designed so that all of the various controls
can be safely reached and the monitors can be
easily viewed by the vehicle operator when driving,
while still allowing relative ease of access to each of
these items for service. See the owner's manual in
the vehicle glove box for more information on the features,
use and operation of all of the instrument
panel components and systems.
This group is responsible for covering service information
for the vehicle instrument panel systems.
However, complete service information coverage for
all of the systems and components housed in the
instrument panel in a single section of the service
manual would not be practical. Therefore, the service
information for any component will be found in the
group designated to cover the vehicle system that the
component belongs to, even though the component is
mounted on or in the instrument panel. If you cannot
locate a listing for the component or system you are
servicing in the table of contents for this group, or if
you are uncertain as to which vehicle system a component
belongs to, it is suggested that you refer to
the alphabetical Component and System Index
found at the back of this service manual.
NOTE: This group covers both Left-Hand Drive
(LHD) and Right-Hand Drive (RHD) versions of this
model. Whenever required and feasible, the RHD
versions of affected vehicle components have been
constructed as mirror-image of the LHD versions.
While most of the illustrations used in this group
represent only the LHD version, the diagnostic and
service procedures outlined can generally be
applied to either version. Exceptions to this rule
have been clearly identified as LHD or RHD, if a
special illustration or procedure is required. DESCRIPTION This instrument panel uses a full-width structural
plastic foundation as its primary support. When the
two primary molded plastic components of this structure
are vibration welded together they provide superior
instrument panel stiffness and integrity to help reduce buzzes, squeaks, and
rattles even on the
bumpiest roads.
This type of construction also provides improved
energy absorption which, in conjunction with the
dual airbag modules and seat belts, helps to improve
occupant protection. This foundation structure also
serves as the air duct for the heating and air conditioning
system panel outlets, which greatly reduces
the number of components used over conventional
instrument panel construction.
Modular instrument panel construction allows all
of the gauges and controls to be serviced from the
front of the panel. In addition, most of the instrument
panel electrical components can be accessed
without complete instrument panel removal. If necessary,
the instrument panel can be removed from the
vehicle as an assembly.
Removal of the steering column opening cover and
knee blocker provides access to the steering column
mounts, the steering column wiring, the headlamp
switch, the electronic combination flasher, and much
of the instrument panel wiring. Removal of the glove
box provides access to the heating and air conditioning
electrical and vacuum harnesses, the blower
motor relay, the radio antenna coaxial cable, the
lower passenger side airbag mounts, and additional
instrument panel wiring.
Removal of the instrument panel center bezel
allows access to the radio, the heating and air conditioning
controls, the accessory switches, the cigar
lighter, and the accessory power outlet. Removal of
the instrument cluster bezel allows access to the
instrument cluster. Removal of the cluster assembly
allows access to the cluster illumination and indicator
lamp bulbs, and more of the instrument panel
wiring.
Removal of the instrument panel top cover allows
access to the upper passenger side airbag mounts.
Instrument panel removal is required for service of
most internal components of the heating and air conditioning
system housing. DESCRIPTION Two basic instrument clusters are offered on this
model: low-line, or high-line. Both clusters are electromechanical
units that utilize integrated circuitry
and information carried on the Chrysler Collision
Detection (CCD) data bus network for control of all
gauges and many of the indicator lamps. These clusters
also incorporate a digital Vacuum Fluorescent
Display (VFD) for the odometer/trip odometer display
functions. Some variations of each cluster exist due
to optional equipment and regulatory requirements.
The low-line cluster includes the following analog
gauges: This cluster also includes provisions for the following
indicator lamps: The high-line cluster replaces some of the indicator
lamps found in the low-line cluster with analog
gauges. The high-line cluster includes the following
analog gauges: The high-line cluster also adds a check gauges
lamp and a low fuel warning lamp to the remaining
indicator lamps found in the low-line cluster.
Both instrument clusters feature circuitry that has
a self-diagnostic actuator test capability, which will
test each of the CCD bus message-controlled functions
of the cluster by lighting the appropriate indicator
lamps and positioning the gauge needles at
several predetermined locations on the gauge faces in
a prescribed sequence. For more information on this
function, refer to Instrument Cluster in the Diagnosis
and Testing section of this group.
The instrument cluster circuitry also integrates a
chime tone generator and a timer circuit. These
items replace the chime or buzzer module, and the
separate timer circuit for the rear window defogger
system. Refer to Chime Warning System in the
Description and Operation section of Group 8U -
Chime/Buzzer Warning Systems for more information
on the chime functions of the instrument cluster.
Refer to Rear Window Defogger System in the
Description and Operation section of Group 8N - Electrically Heated Systems for
more information on
the timer function of the instrument cluster.
The instrument clusters for this model are serviced
only as complete units. If a cluster gauge or the cluster
circuit board are faulty, the entire cluster must be
replaced. The cluster lens, the cluster hood and
mask, the rear cluster housing cover, the odometer
reset knob boot and the incandescent lamp bulbs and
holders are available for service replacement. OPERATION GAUGE With the ignition switch in the On or Start positions,
voltage is supplied to all gauges through the
instrument cluster electronic circuit board. With the
ignition switch in the Off position, voltage is not supplied
to the gauges. The gauges do not accurately
indicate any vehicle condition unless the ignition
switch is in the On or Start positions.
All of the instrument cluster gauges, except the
odometer, are air core magnetic units. Two fixed electromagnetic
coils are located within the gauge. These
coils are wrapped at right angles to each other
around a movable permanent magnet. The movable
magnet is suspended within the coils on one end of a
shaft. The gauge needle is attached to the other end
of the shaft.
One of the coils has a fixed current flowing
through it to maintain a constant magnetic field
strength. Current flow through the second coil
changes, which causes changes in its magnetic field
strength. The current flowing through the second coil
is changed by the instrument cluster electronic circuitry
in response to messages received on the
Chrysler Collision Detection (CCD) data bus network.
The gauge needle moves as the movable permanent
magnet aligns itself to the changing magnetic fields
created around it by the electromagnets. The instrument
cluster circuitry is programmed to move all of
the gauge needles back to the low end of their respective
scales after the ignition switch is turned to the
Off position. INDICATOR LAMP Indicator lamps are located in the instrument cluster
and are served by the cluster circuit board and
connectors. Many of the indicator lamps in the
instrument cluster are controlled by the instrument
cluster circuitry in response to messages received
over the Chrysler Collision Detection (CCD) data bus
network.
The anti-lock brake system lamp, brake warning
lamp, four-wheel drive indicator lamps, headlamp
high beam indicator lamp, low washer fluid warning
lamp and turn signal indicator lamps are hard wired.
The seat belt reminder lamp is controlled by the
instrument cluster programming. The Malfunction
Indicator Lamp (MIL) is normally controlled by CCD
data bus messages from the Powertrain Control Module
(PCM); however, if the instrument cluster detects
a loss of CCD data bus communication, the cluster
will automatically turn the MIL on and display the
message "NO BUS" in the odometer VFD until CCD
data bus communication is restored. The instrument
cluster circuitry uses CCD data bus messages from
the Powertrain Control Module (PCM), Airbag Control
Module (ACM), and the Sentry Key Immobilizer
Module (SKIM) to control all of the remaining indicator
lamps.
Each of the indicator lamps in the instrument cluster
uses incandescent bulbs and holders, which are
available for service replacement. CLUSTER ILLUMINATION LAMP The cluster illumination lamps are hard wired in
the instrument cluster. When the park or head lamps
are turned on, the cluster illumination lamps light.
Illumination brightness is adjusted by rotating the
headlamp switch knob (clockwise to dim, counterclockwise
to brighten). The instrument cluster illumination
lamps receive battery feed from the panel
dimmer rheostat in the headlamp switch through a
fuse in the fuseblock module.
The instrument cluster electronic circuitry also
monitors the cluster illumination lamp dimming level
whenever the park or head lamps are turned on. The
instrument cluster electronic circuitry responds by
adjusting the dimming level of the odometer Vacuum
Fluorescent Display (VFD), and sending dimming
level messages over the Chrysler Collision Detection
(CCD) data bus network. When the park lamps or
headlamps are turned off, the VFD is illuminated at
full brightness for improved daylight visibility.
Each of the cluster illumination lamps is located on
the instrument cluster circuit board. Each cluster
illumination lamp has a replaceable bulb and bulb
holder. DESCRIPTION A cigar lighter is standard equipment on this
model. The cigar lighter is installed in the instrument
panel accessory switch bezel, which is located
near the bottom of the instrument panel center bezel
area, below the heater and air conditioner controls.
The cigar lighter base is secured by a snap fit within
the accessory switch bezel.
The cigar lighter receptacle is serviced only as a
part of the accessory switch bezel unit. If the cigar
lighter base is faulty or damaged, the accessory switch bezel unit must be
replaced. The cigar lighter
knob and heating element unit is available for service.
This component cannot be repaired and, if
faulty or damaged, it must be replaced. OPERATION The cigar lighter consists of two major components:
a knob and heating element unit, and the cigar
lighter base or receptacle shell. The receptacle shell
is connected to ground, and an insulated contact in
the bottom of the shell is connected to battery current.
The cigar lighter receives battery voltage from a
fuse in the junction block through the cigar lighter
relay only when the ignition switch is in the Accessory
or On positions. Refer to Cigar Lighter Relay
in the Description and Operation section of this
group for more information on this component.
The cigar lighter knob and heating element are
encased within a spring-loaded housing, which also
features a sliding protective heat shield. When the
knob and heating element are inserted in the receptacle
shell, the heating element resistor coil is
grounded through its housing to the receptacle shell.
If the cigar lighter knob is pushed inward, the heat
shield slides up toward the knob exposing the heating
element, and the heating element extends from
the housing toward the insulated contact in the bottom
of the receptacle shell.
Two small spring-clip retainers are located on
either side of the insulated contact inside the bottom
of the receptacle shell. These clips engage and hold
the heating element against the insulated contact
long enough for the resistor coil to heat up. When the
heating element is engaged with the contact, battery
current can flow through the resistor coil to ground,
causing the resistor coil to heat.
When the resistor coil becomes sufficiently heated,
excess heat radiates from the heating element causing
the spring-clips to expand. Once the spring-clips
expand far enough to release the heating element,
the spring-loaded housing forces the knob and heating
element to pop back outward to their relaxed
position. When the cigar lighter knob and element
are pulled out of the receptacle shell, the protective
heat shield slides downward on the housing so that
the heating element is recessed and shielded around
its circumference for safety. DESCRIPTION The cigar lighter relay is an electromechanical
device that switches fused battery current to the
cigar lighter when the ignition switch is turned to
the Accessory or On positions. The cigar lighter relay
is located in the junction block, on the right cowl side
panel below the instrument panel in the passenger
compartment.
The cigar lighter relay is a International Standards
Organization (ISO) relay. Relays conforming to the
ISO specifications have common physical dimensions,
current capacities, terminal patterns, and terminal
functions.
The cigar lighter relay cannot be repaired or
adjusted and, if faulty or damaged, it must be
replaced. OPERATION The ISO relay consists of an electromagnetic coil, a
resistor or diode, and three (two fixed and one movable)
electrical contacts. The movable (common feed)
relay contact is held against one of the fixed contacts
(normally closed) by spring pressure. When the electromagnetic
coil is energized, it draws the movable
contact away from the normally closed fixed contact,
and holds it against the other (normally open) fixed
contact.
When the electromagnetic coil is de-energized,
spring pressure returns the movable contact to the
normally closed position. The resistor or diode is connected
in parallel with the electromagnetic coil in the
relay, and helps to dissipate voltage spikes that are
produced when the coil is de-energized. DESCRIPTION An accessory power outlet is standard equipment
on this model. The power outlet is installed in the
instrument panel accessory switch bezel, which is
located near the bottom of the instrument panel center
bezel area, below the heater and air conditioner
controls. The power outlet base is secured by a snap
fit within the accessory switch bezel. A plastic protective
cap snaps into the power outlet base when the
power outlet is not being used, and hangs from the
power outlet base mount by an integral bail strap
while the power outlet is in use.
The power outlet receptacle unit and the accessory
power outlet protective cap are serviced only as a
part of the accessory switch bezel unit. If the power
outlet base is faulty or damaged, the entire accessory
switch bezel unit must be replaced. OPERATION The power outlet base or receptacle shell is connected
to ground, and an insulated contact in the
bottom of the shell is connected to battery current.
The power outlet receives battery voltage from a fuse
in the junction block at all times.
While the power outlet is very similar to a cigar
lighter base unit, it does not include the two small spring-clip retainers
inside the bottom of the receptacle
shell that are used to secure the cigar lighter
heating element to the insulated contact.Instrument panel system
Instrument panel
Instrument cluster
Instrument panel cigar lighter
Cigar lighter relay
Instrument panel power outlet
Other materials:
Windshield Wiper Blades
Clean the rubber edges of the wiper blades and the
windshield periodically with a sponge or soft cloth and a
mild nonabrasive cleaner. This will remove accumulations
of salt or road film.
Operation of the wipers on dry glass for long periods
may cause deterioration of the wiper blades. Always u ...