Dodge 2000 DURANGO Service Manual page 442

8N - 2 ELECTRICALLY HEATED SYSTEMS
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 heating 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 terminals.
OUTSIDE MIRROR HEATING GRID
Vehicles equipped with the optional heated mirror
system 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 are both inoper-
ative, see Rear Window Defogger System in the Diag-
nosis and Testing section of this group. If only one of
the outside mirror heating grids is inoperative, see
Power Mirror System in the Diagnosis and Testing
section of Group 8T - Power Mirror Systems for diag-
nosis of the outside mirror heating grid.
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 integral to the
rear window switch pod, which includes the rear
wiper and washer switches. The rear window switch
pod is installed in the instrument panel lower bezel,
which is located near the center of the lower instru-
ment panel, below the heater and air conditioner con-
trols.
The rear window switch pod also contains the rear
window defogger logic and timer circuitry, an amber
defogger indicator lamp, the rear window defogger
relay, and two switch illumination lamps. The indica-
tor and illumination lamps in the switch pod use
incandescent bulbs, which can be serviced.
The momentary-type rear window defogger switch
provides a hard wired ground signal to the rear win-
dow defogger logic and timer circuitry, each time it is
depressed. The rear window defogger timer and logic
circuitry responds by energizing or de-energizing the
rear window defogger relay and the amber defogger
indicator lamp, which lights to indicate when the
defogger system is turned On. Energizing the rear
window defogger relay provides electrical current to
the rear window defogger grid.
The rear window switch pod cannot be repaired. If
any function of the switch pod except lighting is
faulty or damaged, the entire switch pod must be
replaced.
DIAGNOSIS AND TESTING
DEFOGGER SYSTEM
For circuit descriptions and diagrams, refer to
8W-48 - Rear Window Defogger in Group 8W - Wir-
ing Diagrams. The operation of the electrically
heated rear window defogger system can be con-
firmed in one of the following manners:
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 rear window defogger logic and timer
circuitry, but does not confirm that the electrical cur-
rent is reaching the rear glass heating grid lines.
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