electrically heated outside rear view mirrors are
available factory-installed options on this model.
Refer to 8W-48 - Rear Window Defogger and 8W-62 -
Power Mirrors in Group 8W - Wiring Diagrams for
complete circuit descriptions and diagrams.

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

applied to either version. Exceptions to this rule
have been clearly identified as LHD or RHD, if a
special illustration or procedure is required.

REAR WINDOW DEFOGGER SYSTEM

The rear window defogger system will only operate

when the ignition switch is in the On position. When
the defogger switch is in the On position, an electric
heater grid on the rear window glass is energized.
Vehicles with the heated mirror options also have
heater grids located behind the outside rear view
mirror glass. Each of these grids produce heat to help
clear the rear window glass and outside rear view
mirrors of ice, snow, or fog.

The defogger system is controlled by a switch

installed in the instrument panel accessory switch
bezel, which is located near the bottom of the instru-
ment panel center bezel area, below the heater and
air conditioner controls. An amber indicator lamp in
the switch button will light to indicate when the
defogger system is turned on. The instrument cluster
circuitry, which contains the defogger system timer
logic, monitors the state of the defogger switch
through a hard-wired input. The instrument cluster
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

ELECTRICALLY HEATED SYSTEMS

8N - 1

the defogger switch is turned on again during the
same ignition cycle, the defogger system will auto-
matically turn off after about five minutes.

The defogger system will automatically shut off if

the ignition switch is turned to the Off position, or it
can be turned off manually by depressing the instru-
ment panel switch. Following are general descrip-
tions of the major components in the defogger
system. Refer to the owner’s manual in the vehicle
glove box for more information on the features, use
and operation of the defogger system.

DESCRIPTION AND OPERATION

REAR GLASS HEATING GRID

The heated rear window glass has two electrically

conductive vertical bus bars and a series of horizon-
tal grid lines made of a silver-ceramic material,
which is baked on and bonded to the inside surface of
the glass. The grid lines and bus bars comprise a
parallel electrical circuit.

When the rear window defogger switch is placed in

the On position, electrical current is directed to the
rear window grid lines through the bus bars. The
grid lines heat the rear window to clear the surface
of fog or snow. Protection for the heated grid circuit
is provided by a fuse in the Power Distribution Cen-
ter (PDC).

The grid lines and bus bars are highly resistant to

abrasion. However, it is possible for an open circuit
to occur in an individual grid line, resulting in no
current flow through the line.

The grid lines can be damaged or scraped off with

sharp instruments. Care should be taken when clean-
ing the glass or removing foreign materials, decals,
or stickers from the glass. Normal glass cleaning sol-
vents or hot water used with rags or toweling is rec-
ommended.

A repair kit is available to repair the grid lines and

bus bars, or to reinstall the heated glass pigtail
wires.

OUTSIDE MIRROR HEATING GRID

Vehicles equipped with the optional heated mirror

package have an electric heating grid located behind
the mirror glass of each outside rear view mirror.
The heated mirrors are controlled by the rear win-
dow defogger switch. Electrical current is directed to
the heating grid inside the mirror only when the rear
window defogger switch is in the On position.

If the outside mirror heating grids and the rear

window heating grid are all inoperative, diagnosis of
the rear window defogger system should be per-
formed as described in this group. If the outside mir-
ror heating grids are inoperative, but the rear

window heating grid is operating as designed, refer
to Power Mirror in the Diagnosis and Testing section
of Group 8T - Power Mirror Systems for diagnosis of
the mirror heating grids.

The heating grid behind each outside mirror glass

cannot be repaired and, if faulty or damaged, the
entire power mirror unit must be replaced. Refer to
Power Mirror in the Removal and Installation section
of Group 8T - Power Mirror Systems for the service
procedures.

DEFOGGER SWITCH

The rear window defogger switch is installed in the

instrument panel accessory switch bezel, which is
located near the bottom of the instrument panel cen-
ter bezel area, below the heater and air conditioner
controls. The momentary-type switch provides a
hard-wired ground signal to the instrument cluster
each time it is depressed. The instrument cluster
rear window defogger timer and logic circuitry
responds by energizing or de-energizing the rear win-
dow defogger relay.

Energizing the rear window defogger relay pro-

vides electrical current to the rear window defogger
grid and, if the vehicle is so equipped, the outside
rear view mirror heating grids. An amber indicator
lamp in the defogger switch, which lights to indicate
when the defogger system is turned On, is also pow-
ered by the defogger relay output.

The defogger switch illumination lamp and indica-

tor lamp bulbs are serviceable. The defogger switch
cannot be repaired and, if faulty or damaged, it must
be replaced.

INSTRUMENT CLUSTER

The instrument cluster is an electromechanical

unit that contains integrated circuitry and internal
programming to perform a variety of functions. The
instrument cluster circuitry monitors hard-wired
switch inputs, as well as message inputs received
from other vehicle electronic control modules on the
Chrysler Collision Detection (CCD) data bus network.

The instrument cluster uses these many inputs

along with its internal programming and integral
timer and logic circuitry to perform the functions of
the rear window defogger timer on this model. The
instrument cluster circuitry also has a self-diagnostic
capability. Refer to Instrument Cluster in Group 8E -
Instrument Panel Systems for more information on
this feature.

However, there are no diagnostics available for the

rear window defogger timer and logic circuitry.
Therefore, the diagnosis for this system consists of
confirming the presence of a rear window defogger
switch input signal at the instrument cluster connec-
tor, and the resulting rear window defogger relay

8N - 2

ELECTRICALLY HEATED SYSTEMS

GENERAL INFORMATION (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
and outside mirror heating grids, and the indicator
lamp of the defogger switch, when the instrument
cluster rear window defogger timer and logic cir-
cuitry grounds the relay coil. See Defogger Relay in
the Diagnosis and Testing section of this group for
more information.

The rear window defogger relay is located in the

junction block, on the right cowl side inner panel
below the instrument panel in the passenger com-
partment. The rear window defogger relay cannot be
repaired and, if faulty or damaged, it must be
replaced.

DIAGNOSIS AND TESTING

DEFOGGER SYSTEM

For circuit descriptions and diagrams, refer to

8W-48 - Rear Window Defogger or 8W-62 Power Mir-
rors in Group 8W - Wiring Diagrams. The operation
of the electrically heated rear window defogger sys-
tem can be confirmed in one of the following man-
ners:

1. Turn the ignition switch to the On position.

While monitoring the instrument panel voltmeter, set
the defogger switch in the On position. When the
defogger switch is turned On, a distinct voltmeter
needle deflection should be noted.

2. Turn the ignition switch to the On position. Set

the defogger switch in the On position. The rear win-
dow defogger operation can be checked by feeling the
rear window or outside rear view mirror glass. A dis-
tinct difference in temperature between the grid lines
and the adjacent clear glass or the mirror glass can
be detected within three to four minutes of operation.

3. Using a 12-volt DC voltmeter, contact the rear

glass heating grid terminal A (right side) with the
negative lead, and terminal B (left side) with the pos-
itive lead (Fig. 1). The voltmeter should read battery
voltage.

The above checks will confirm system operation.

Illumination of the defogger switch indicator lamp
means that there is electrical current available at the
output of the defogger relay, but does not confirm
that the electrical current is reaching the rear glass
heating grid lines.

If the defogger system does not operate, the prob-

lem should be isolated in the following manner:

(1) Confirm that the ignition switch is in the On

position.

(2) Ensure that the rear glass heating grid feed

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-

ter (PDC) and in the junction block. The fuses must
be tight in their receptacles and all electrical connec-
tions must be secure.

When the above steps have been completed and the

rear glass or outside rear view mirror heating grid is
still inoperative, one or more of the following is
faulty:

• Defogger switch

• Defogger relay

• Instrument cluster circuitry

• Rear window grid lines (all grid lines would

have to be broken or one of the feed wires discon-
nected for the entire system to be inoperative)

• Outside rear view mirror heating grid.
If setting the defogger switch to the On position

produces a severe voltmeter deflection, check for a
short circuit between the defogger relay output and
the rear glass or outside rear view mirror heating
grids.

Fig. 1 Rear Window Glass Grid Test

1 – TERMINAL “A”
2 – TERMINAL “B”
3 – FEED WIRE
4 – MID-POINT “C” (TYPICAL)
5 – HEATED REAR WINDOW DEFOGGER GRID
6 – GROUND WIRE

ELECTRICALLY HEATED SYSTEMS

8N - 3

DESCRIPTION AND OPERATION (Continued)

Content .. 133 134 135 136 ..