Service Manuals, User Guides, Schematic Diagrams or docs for : . Car Manuals Jeep Cherokee XJ 1997.1999-2001 Approved 1999 XJ Jeep Cherokee EXJ_8N
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XJ ELECTRICALLY HEATED SYSTEMS 8N - 1
ELECTRICALLY HEATED SYSTEMS
CONTENTS
page page
HEATED SEAT SYSTEM . . . . . . . . . . . . . . . . . . . . 8 REAR WINDOW DEFOGGER SYSTEM . . . . . . . . . 1
REAR WINDOW DEFOGGER SYSTEM
INDEX
page page
GENERAL INFORMATION DEFOGGER SWITCH . . . . . . . . . . . . . . . . . . . . . . 4
INTRODUCTION . . . . . . . . . . . . . . . . . ........ 1 DEFOGGER SYSTEM . . . . . . . . . . . . . . . . . . . . . 3
REAR WINDOW DEFOGGER SYSTEM ........ 1 INSTRUMENT CLUSTER . . . . . . . . . . . . . . . . . . . 5
DESCRIPTION AND OPERATION REAR GLASS HEATING GRID . . . . . . . . . . . . . . . 3
DEFOGGER RELAY . . . . . . . . . . . . . . . . . . . . . . . 3 SERVICE PROCEDURES
DEFOGGER SWITCH . . . . . . . . . . . . . . . . . . . . . . 2 REAR GLASS HEATING GRID REPAIR ........ 6
INSTRUMENT CLUSTER . . . . . . . . . . . . . . . . . . . 2 REMOVAL AND INSTALLATION
OUTSIDE MIRROR HEATING GRID . . . . . . . . . . . 2 DEFOGGER RELAY . . . . . . . . . . . . . . . ........ 7
REAR GLASS HEATING GRID . . . . . . . . . . . . . . . 2 DEFOGGER SWITCH . . . . . . . . . . . . . . ........ 6
DIAGNOSIS AND TESTING
DEFOGGER RELAY . . . . . . . . . . . . . . . ........ 4
GENERAL INFORMATION REAR WINDOW DEFOGGER SYSTEM
The rear window defogger system will only operate
INTRODUCTION when the ignition switch is in the On position. When
An electrically heated rear window defogger and the defogger switch is in the On position, an electric
electrically heated outside rear view mirrors are heater grid on the rear window glass is energized.
available factory-installed options on this model. Vehicles with the heated mirror options also have
Refer to 8W-48 - Rear Window Defogger and 8W-62 - heater grids located behind the outside rear view
Power Mirrors in Group 8W - Wiring Diagrams for mirror glass. Each of these grids produce heat to help
complete circuit descriptions and diagrams. clear the rear window glass and outside rear view
mirrors of ice, snow, or fog.
NOTE: This group covers both Left-Hand Drive The defogger system is controlled by a switch
(LHD) and Right-Hand Drive (RHD) versions of this installed in the instrument panel accessory switch
model. Whenever required and feasible, the RHD bezel, which is located near the bottom of the instru-
versions of affected vehicle components have been ment panel center bezel area, below the heater and
constructed as mirror-image of the LHD versions. air conditioner controls. An amber indicator lamp in
While most of the illustrations used in this group the switch button will light to indicate when the
represent only the LHD version, the diagnostic and defogger system is turned on. The instrument cluster
service procedures outlined can generally be circuitry, which contains the defogger system timer
applied to either version. Exceptions to this rule logic, monitors the state of the defogger switch
have been clearly identified as LHD or RHD, if a through a hard-wired input. The instrument cluster
special illustration or procedure is required. circuitry controls the defogger system through a
hard-wired control output to the defogger relay.
The defogger system will be automatically turned
off after a programmed time interval of about ten
minutes. After the initial time interval has expired, if
8N - 2 ELECTRICALLY HEATED SYSTEMS XJ
GENERAL INFORMATION (Continued)
the defogger switch is turned on again during the window heating grid is operating as designed, refer
same ignition cycle, the defogger system will auto- to Power Mirror in the Diagnosis and Testing section
matically turn off after about five minutes. of Group 8T - Power Mirror Systems for diagnosis of
The defogger system will automatically shut off if the mirror heating grids.
the ignition switch is turned to the Off position, or it The heating grid behind each outside mirror glass
can be turned off manually by depressing the instru- cannot be repaired and, if faulty or damaged, the
ment panel switch. Following are general descrip- entire power mirror unit must be replaced. Refer to
tions of the major components in the defogger Power Mirror in the Removal and Installation section
system. Refer to the owner's manual in the vehicle of Group 8T - Power Mirror Systems for the service
glove box for more information on the features, use procedures.
and operation of the defogger system.
DEFOGGER SWITCH
The rear window defogger switch is installed in the
DESCRIPTION AND OPERATION instrument panel accessory switch bezel, which is
located near the bottom of the instrument panel cen-
REAR GLASS HEATING GRID ter bezel area, below the heater and air conditioner
The heated rear window glass has two electrically controls. The momentary-type switch provides a
conductive vertical bus bars and a series of horizon- hard-wired ground signal to the instrument cluster
tal grid lines made of a silver-ceramic material, each time it is depressed. The instrument cluster
which is baked on and bonded to the inside surface of rear window defogger timer and logic circuitry
the glass. The grid lines and bus bars comprise a responds by energizing or de-energizing the rear win-
parallel electrical circuit. dow defogger relay.
When the rear window defogger switch is placed in Energizing the rear window defogger relay pro-
the On position, electrical current is directed to the vides electrical current to the rear window defogger
rear window grid lines through the bus bars. The grid and, if the vehicle is so equipped, the outside
grid lines heat the rear window to clear the surface rear view mirror heating grids. An amber indicator
of fog or snow. Protection for the heated grid circuit lamp in the defogger switch, which lights to indicate
is provided by a fuse in the Power Distribution Cen- when the defogger system is turned On, is also pow-
ter (PDC). ered by the defogger relay output.
The grid lines and bus bars are highly resistant to The defogger switch illumination lamp and indica-
abrasion. However, it is possible for an open circuit tor lamp bulbs are serviceable. The defogger switch
to occur in an individual grid line, resulting in no cannot be repaired and, if faulty or damaged, it must
current flow through the line. be replaced.
The grid lines can be damaged or scraped off with
sharp instruments. Care should be taken when clean- INSTRUMENT CLUSTER
ing the glass or removing foreign materials, decals, The instrument cluster is an electromechanical
or stickers from the glass. Normal glass cleaning sol- unit that contains integrated circuitry and internal
vents or hot water used with rags or toweling is rec- programming to perform a variety of functions. The
ommended. instrument cluster circuitry monitors hard-wired
A repair kit is available to repair the grid lines and switch inputs, as well as message inputs received
bus bars, or to reinstall the heated glass pigtail from other vehicle electronic control modules on the
wires. Chrysler Collision Detection (CCD) data bus network.
The instrument cluster uses these many inputs
OUTSIDE MIRROR HEATING GRID along with its internal programming and integral
Vehicles equipped with the optional heated mirror timer and logic circuitry to perform the functions of
package have an electric heating grid located behind the rear window defogger timer on this model. The
the mirror glass of each outside rear view mirror. instrument cluster circuitry also has a self-diagnostic
The heated mirrors are controlled by the rear win- capability. Refer to Instrument Cluster in Group 8E -
dow defogger switch. Electrical current is directed to Instrument Panel Systems for more information on
the heating grid inside the mirror only when the rear this feature.
window defogger switch is in the On position. However, there are no diagnostics available for the
If the outside mirror heating grids and the rear rear window defogger timer and logic circuitry.
window heating grid are all inoperative, diagnosis of Therefore, the diagnosis for this system consists of
the rear window defogger system should be per- confirming the presence of a rear window defogger
formed as described in this group. If the outside mir- switch input signal at the instrument cluster connec-
ror heating grids are inoperative, but the rear tor, and the resulting rear window defogger relay
XJ ELECTRICALLY HEATED SYSTEMS 8N - 3
DESCRIPTION AND OPERATION (Continued)
control output signal at the defogger relay. For diag-
nosis of the CCD data bus and the data bus message
inputs, a DRB scan tool and the proper Diagnostic
Procedures manual are recommended.
Refer to Instrument Cluster in Group 8E - Instru-
ment Panel Systems for the service procedures for
the instrument cluster. The rear window defogger
timer and logic circuitry cannot be adjusted or
repaired and, if faulty or damaged, the instrument
cluster assembly must be replaced.
DEFOGGER RELAY
The rear window defogger relay is a International
Standards Organization (ISO)-type relay. The rear
window defogger relay is a electromechanical device
that switches fused battery current to the rear glass Fig. 1 Rear Window Glass Grid Test
and outside mirror heating grids, and the indicator The above checks will confirm system operation.
lamp of the defogger switch, when the instrument Illumination of the defogger switch indicator lamp
cluster rear window defogger timer and logic cir- means that there is electrical current available at the
cuitry grounds the relay coil. See Defogger Relay in output of the defogger relay, but does not confirm
the Diagnosis and Testing section of this group for that the electrical current is reaching the rear glass
more information. heating grid lines.
The rear window defogger relay is located in the If the defogger system does not operate, the prob-
junction block, on the right cowl side inner panel lem should be isolated in the following manner:
below the instrument panel in the passenger com- (1) Confirm that the ignition switch is in the On
partment. The rear window defogger relay cannot be position.
repaired and, if faulty or damaged, it must be (2) Ensure that the rear glass heating grid feed
replaced. and ground wires are connected to the glass. Confirm
that the ground wire has continuity to ground.
(3) Check the fuses in the Power Distribution Cen-
DIAGNOSIS AND TESTING ter (PDC) and in the junction block. The fuses must
be tight in their receptacles and all electrical connec-
DEFOGGER SYSTEM tions must be secure.
For circuit descriptions and diagrams, refer to When the above steps have been completed and the
8W-48 - Rear Window Defogger or 8W-62 Power Mir- rear glass or outside rear view mirror heating grid is
rors in Group 8W - Wiring Diagrams. The operation still inoperative, one or more of the following is
of the electrically heated rear window defogger sys- faulty:
tem can be confirmed in one of the following man- ◦ Jabse Service Manual Search 2024 ◦ Jabse Pravopis ◦ onTap.bg ◦ Other service manual resources online : Fixya ◦ eServiceinfo