The Electric Rear Window Defogger is standard equipment. A push button Rear Window Defogger Switch (2)
located in the center console activates the rear window defogger. The switch is illuminated with instrumentation
lighting for easy night time use. An LED (1) in the push button switch illuminates when the rear window defogger is
working. When energized, a grid on the inside of the window heats up to help clear the outside surface of ice, snow
or fog. The sideview mirrors are also equipped with heating elements that work in conjunction with the rear window
defogger. For diagnosis of the heated mirrors, refer to Heated Mirrors-Electrical Diagnostics in this section.

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HEATED GLASS - SERVICE INFORMATION

OPERATION

When the Rear Window Defogger Switch (2) is
pressed with the Ignition Switch turned to the ON/RUN
position, electrical current from Fuses 25 and 26 in the
Underhood Accessory Fuse Block is applied to the
rear window defogger grid. An LED (1) in the push
button switch illuminates when the rear window defog-
ger is activated.

On the Coupe model, the rear defogger grid is com-
prised

horizontal

silver-ceramic

grid

lines

(1)

through the two vertical bus bars (2) on the glass
inside surface. When the circuit is operating, the grid
lines provide heat in the form of resistance. The heat
is transferred to the outside surface to clear fog or
snow. The grid lines comprise a parallel electrical cir-
cuit and are bonded to the glass permanently. Both
the horizontal grid lines (1) and the vertical bus bars
(2) are highly resistant to abrasion. However, it is pos-
sible for an open circuit to occur in an individual grid
line resulting in no current flow. Care should be taken
when cleaning the glass or removing foreign materials,
decals or stickers. Normal glass cleaning solvents or
hot water is recommended for cleaning. The grid lines
and bus bars are repairable if they become damaged.
For complete heated grid line and bus bar repair
instructions see rear window defogger grid standard
procedure in this section. (Refer to 8 - ELECTRICAL/
HEATED GLASS/REAR WINDOW DEFOGGER GRID
- STANDARD PROCEDURE).

HEATED GLASS - SERVICE INFORMATION

8G - 13

On the Roadster model, the rear defogger grid is com-
prised

horizontal

silver-ceramic

grid

lines

(1)

DIAGNOSIS AND TESTING - REAR WINDOW DEFOGGER SYSTEM

For complete heated glass electrical diagnosis with schematics and diagrams, see the appropriate Heated Glass
Electrical Diagnostics in this section. For complete heated mirror electrical diagnosis with schematics and diagrams,
see the appropriate Heated Mirror Electrical Diagnostics in this section.

The operation of the Electrically Heated Rear Window Defogger System can be confirmed in the following manner:

1. Turn the ignition switch to the ON/RUN position.

2. Press the Defogger Switch to the ON position. The rear window defogger operation can be checked by feeling
the rear window glass and the side view mirrors. A distinct difference in temperature between the grid lines and
the adjacent clear 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 (right side) with the negative lead
and the opposite terminal (left side) with the positive lead. The voltmeter should read battery voltage.

The above checks will confirm system operation. Illumination of the Defogger Switch indicator lamp indicates that
there is electrical current available at the A/C Heater Control Module but does not confirm that the electrical current
is reaching the rear glass heating grid lines and the side view mirrors.

If the defogger system does not operate, the problem should be isolated in the following manner:

1. Confirm that the ignition switch is in the ON/RUN position.

2. Ensure that the rear glass heating grid power feed, and ground wires are connected to the glass.

3. Confirm that the ground wire has continuity to ground.

4. Ensure that each of the power mirrors are fully functional.

5. Check Fuses 4, 25 and 26 in the Underhood Accessory Fuse Block. The fuses must be tight in their receptacles

and all electrical connections must be clean and secure.

When the above steps have been completed and the rear glass heating grid/heated mirrors are still inoperative, one
or more of the following is faulty:

•

Defogger Switch

•

A/C Heater Control Module circuitry

•

Rear window grid lines (all grid lines would have to be broken or one of the feed wires disconnected for the
entire system to be inoperative)

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HEATED GLASS - SERVICE INFORMATION

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