Electrically Heated Systems - Jeep 1997 Grand Cherokee Service Manual

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DEFOGGER SYSTEM . . . . . . . . . . . . . . . . . . . . . 1
GENERAL INFORMATION
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . 1
DESCRIPTION AND OPERATION
BODY CONTROL MODULE . . . . . . . . . . . . . . . . 2
DEFOGGER RELAY . . . . . . . . . . . . . . . . . . . . . . 2
DEFOGGER SWITCH
HEATED MIRROR . . . . . . . . . . . . . . . . . . . . . . . 2
REAR GLASS HEATING GRID . . . . . . . . . . . . . . 2
DIAGNOSIS AND TESTING
DEFOGGER RELAY . . . . . . . . . . . . . . . . . . . . . . 4
GENERAL INFORMATION
INTRODUCTION
An electrically heated rear window defogger and
electrically heated outside rear view mirrors are
standard factory-installed equipment on this model.
The defogger will only operate when the ignition
switch is in the On position. When the defogger
switch is in the On position, electric heater grids on
the rear window glass and behind the outside rear
view mirror glass are energized. These grids produce
heat to help clear the rear window glass and outside
rear view mirrors of ice, snow, or fog.
This defogger system is controlled by a switch
located inboard of the steering column in the inboard
switch pod on the instrument panel. A Light-Emit-
ting Diode (LED) above the switch button in the
switch pod will light to indicate when the defogger
system is turned on. The Body Control Module
(BCM), which contains the defogger system timer
logic, monitors the state of the defogger switch
through a hard-wired input. The BCM circuitry con-
trols the defogger system through a hard-wired con-
trol output to the defogger relay.
The defogger system will be automatically turned
off after a programmed time interval of about ten

ELECTRICALLY HEATED SYSTEMS

DEFOGGER SYSTEM
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ELECTRICALLY HEATED SYSTEMS
CONTENTS
page
HEATED SEATS . . . . . . . . . . . . . . . . . . . . . . . . . . 7
INDEX
page
DEFOGGER SWITCH
DEFOGGER SYSTEM . . . . . . . . . . . . . . . . . . . . 3
REAR GLASS HEATING GRID . . . . . . . . . . . . . . 3
SERVICE PROCEDURES
REAR GLASS HEATING GRID REPAIR . . . . . . . 5
REMOVAL AND INSTALLATION
DEFOGGER RELAY . . . . . . . . . . . . . . . . . . . . . . 6
DEFOGGER SWITCH
minutes. After the initial time interval has expired, if
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. Refer to the owner's manual for
more information on the defogger system controls
and operation.
Following are general descriptions of the major
components in the defogger system. Refer to 8W-48 -
Rear Window Defogger and 8W-62 - Power Mirrors in
Group 8W - Wiring Diagrams for complete circuit
descriptions and diagrams.
8N - 1
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