Jeep XJ. Manual — part 133
(6) Check for continuity between the rear window
defogger relay control circuit cavities of the right
instrument cluster wire harness connector (connector
B) and the defogger relay receptacle (the cavity for
ISO relay terminal 85) in the junction block. There
should be continuity. If OK, replace the faulty instru-
ment cluster. If not OK, repair the open circuit as
required.
SERVICE PROCEDURES
REAR GLASS HEATING GRID REPAIR
Repair of the rear glass heating grid lines, bus
bars, terminals or pigtail wires can be accomplished
using a Mopar Rear Window Defogger Repair Kit
(Part Number 4267922) or equivalent.
WARNING: MATERIALS
CONTAINED
IN
THE
REPAIR KIT MAY CAUSE SKIN OR EYE IRRITATION.
THE KIT CONTAINS EPOXY RESIN AND AMINE
TYPE HARDENER, WHICH ARE HARMFUL IF SWAL-
LOWED. AVOID CONTACT WITH THE SKIN AND
EYES. FOR SKIN CONTACT, WASH THE AFFECTED
AREAS WITH SOAP AND WATER. FOR CONTACT
WITH THE EYES, FLUSH WITH PLENTY OF WATER.
DO NOT TAKE INTERNALLY. IF TAKEN INTER-
NALLY, INDUCE VOMITING AND CALL A PHYSICIAN
IMMEDIATELY. USE WITH ADEQUATE VENTILA-
TION. DO NOT USE NEAR FIRE OR FLAME. CON-
TAINS FLAMMABLE SOLVENTS. KEEP OUT OF THE
REACH OF CHILDREN.
(1) Mask the repair area so that the conductive
epoxy can be applied neatly. Extend the epoxy appli-
cation onto the grid line or the bus bar on each side
of the break (Fig. 4).
(2) Follow the instructions in the repair kit for
preparing the damaged area.
(3) Remove the package separator clamp and mix
the two conductive epoxy components thoroughly
within the packaging. Fold the package in half and
cut the center corner to dispense the epoxy.
(4) For grid line repairs, mask the area to be
repaired with masking tape or a template.
(5) Apply the epoxy through the slit in the mask-
ing tape or template. Overlap both ends of the break
by at least 19 millimeters (0.75 inch).
(6) For a terminal or pigtail wire replacement,
mask the adjacent areas so the epoxy can be
extended onto the adjacent grid line as well as the
bus bar. Apply a thin layer of epoxy to the area
where the terminal or pigtail wire was fastened and
onto the adjacent grid line.
(7) Apply a thin layer of conductive epoxy to the
terminal or bare wire end of the pigtail and place it
in the proper location on the bus bar. To prevent the
terminal or pigtail wire from moving while the epoxy
is curing, it must be wedged or clamped.
(8) Carefully remove the masking tape or tem-
plate.
CAUTION: Do not allow the glass surface to exceed
204° C (400° F) or the glass may fracture.
(9) Allow the epoxy to cure 24 hours at room tem-
perature, or use a heat gun with a 260° to 371° C
(500° to 700° F) range for fifteen minutes. Hold the
heat gun approximately 25.4 centimeters (10 inches)
from the repair.
(10) After the conductive epoxy is properly cured,
remove the wedge or clamp from the terminal or pig-
tail wire. Do not attach the wire harness connectors
until the curing process is complete.
(11) Check the operation of the rear window defog-
ger glass heating grid.
REMOVAL AND INSTALLATION
DEFOGGER SWITCH
WARNING: ON VEHICLES EQUIPPED WITH AIRBAGS,
REFER TO GROUP 8M - PASSIVE RESTRAINT SYS-
TEMS BEFORE ATTEMPTING ANY STEERING WHEEL,
STEERING COLUMN, OR INSTRUMENT PANEL COM-
PONENT DIAGNOSIS OR SERVICE. FAILURE TO TAKE
THE PROPER PRECAUTIONS COULD RESULT IN
ACCIDENTAL AIRBAG DEPLOYMENT AND POSSIBLE
PERSONAL INJURY.
(1) Disconnect and isolate the battery negative
cable.
Fig. 4 Grid Line Repair - Typical
1 – BREAK
2 – GRID LINE
3 – MASKING TAPE
8N - 6
ELECTRICALLY HEATED SYSTEMS
XJ
DIAGNOSIS AND TESTING (Continued)
(2) Remove the center bezel from the instrument
panel. See Instrument Panel Center Bezel in Group
8E - Instrument Panel Systems for the procedures.
(3) Remove the three screws that secure the acces-
sory switch bezel to the instrument panel (Fig. 5).
(4) Pull the accessory switch bezel out from the
instrument panel far enough to access the wire har-
ness connectors.
(5) Unplug the wire harness connectors from the
rear of the accessory switches and the cigar lighter/
power outlet.
(6) Remove the accessory switch bezel from the
instrument panel.
(7) With a small thin-bladed screwdriver, gently pry
the snap clips at the top and bottom of the rear window
defogger switch receptacle on the back of the accessory
switch bezel and pull the switch out of the bezel.
(8) Reverse the removal procedures to install. Be
certain that both of the switch snap retainers in the
receptacle on the back of the accessory switch bezel
are fully engaged. Tighten the mounting screws to
2.2 N·m (20 in. lbs.).
DEFOGGER RELAY
WARNING: ON VEHICLES EQUIPPED WITH AIRBAGS,
REFER TO GROUP 8M - PASSIVE RESTRAINT SYS-
TEMS BEFORE ATTEMPTING ANY STEERING WHEEL,
STEERING COLUMN, OR INSTRUMENT PANEL COM-
PONENT DIAGNOSIS OR SERVICE. FAILURE TO TAKE
THE PROPER PRECAUTIONS COULD RESULT IN
ACCIDENTAL AIRBAG DEPLOYMENT AND POSSIBLE
PERSONAL INJURY.
(1) Disconnect and isolate the battery negative cable.
(2) Remove the fuse access panel by unsnapping it
from the right cowl side trim panel.
(3) Remove the stamped nut that secures the right
cowl side trim to the junction block stud (Fig. 6).
(4) Remove the screw located above the fuse access
opening that secures the right cowl side trim to the
right cowl side inner panel.
(5) Remove the screw that secures the right door
sill trim and the right cowl side trim to the right
door opening sill.
(6) Remove the right cowl side trim panel from the
vehicle.
(7) Unplug the rear window defogger relay from
the junction block.
(8) Install the defogger relay by aligning the relay
terminals with the cavities in the junction block and
pushing the relay firmly into place.
(9) Connect the battery negative cable.
(10) Test the relay operation.
(11) Reinstall the right cowl side trim and the fuse
access panel. Tighten the mounting screws to 2.2
N·m (20 in. lbs.).
Fig. 5 Accessory Switch Bezel Remove/Install
1 – ACCESSORY SWITCH BEZEL
2 – SCREW
Fig. 6 Right Cowl Side Trim Remove/Install
1 – RIGHT FRONT DOOR SILL
2 – COWL SIDE TRIM PANEL
3 – SCREW
4 – SILL TRIM
5 – FUSE ACCESS PANEL
6 – PUSH-NUT
XJ
ELECTRICALLY HEATED SYSTEMS
8N - 7
REMOVAL AND INSTALLATION (Continued)
HEATED SEAT SYSTEM
TABLE OF CONTENTS
page
page
GENERAL INFORMATION
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . 8
DESCRIPTION AND OPERATION
HEATED SEAT SWITCH. . . . . . . . . . . . . . . . . . . . . 8
SEAT HEAT INTERFACE MODULE. . . . . . . . . . . . . 9
HEATED SEAT RELAY . . . . . . . . . . . . . . . . . . . . . . 9
HEATED SEAT ELEMENT and SENSOR . . . . . . . . 9
DIAGNOSIS AND TESTING
HEATED SEAT SYSTEM . . . . . . . . . . . . . . . . . . . . 9
HEATED SEAT SWITCH . . . . . . . . . . . . . . . . . . . . 10
HEATED SEAT ELEMENT and SENSOR. . . . . . . . 11
HEATED SEAT RELAY . . . . . . . . . . . . . . . . . . . . . 11
SEAT HEAT INTERFACE MODULE. . . . . . . . . . . . 12
REMOVAL AND INSTALLATION
GENERAL INFORMATION
INTRODUCTION
Individually controlled electrically heated front
seats are available factory-installed optional equip-
ment on this model. The seat heaters will only oper-
ate when the ignition switch is in the ON position,
and the surface temperature at the front seat heating
element sensors is below the designed temperature
set points of the system. The heated seat system will
not operate in ambient temperatures greater than
about 32° C (90° F).
There are separate momentary, tactile, two-direc-
tional rocker switches located in the center console
with center NEUTRAL, HI and LO positions for each
front seat. Depressing the rocker switch to its
momentary HI or LO position signals the Seat Heat
Interface Module (SHIM) to power the selected
heated seat and maintain the requested temperature
setting (HI or LO). Each switch has a HI and LO
Light-Emitting Diode (LED) which, via the SHIM,
illuminates to give a visual indication that the sys-
tem is in the HI or LO mode. The LO heat set point
is about 32° C (90° F), and the HI heat set point is
about 38° C (100° F). The system shall be deactivated
whenever the same set position is depressed a second
time and shall change states directly when switching
from HI to LO or vice versa. The system shall be
deactivated whenever the ignition switch is placed in
the off position. When the ignition switch is placed
back in the run position, the heated seat system
shall remain deactivated until a momentary switch is
depressed. When a seat heater is turned on, a sensor
located near the seat cushion electric heater element
provides the SHIM with input indicating the surface
temperature of the seat cushion. If the surface tem-
perature input is below the temperature set point of
the SHIM for the selected temperature setting, an
N-FET Transistor within the SHIM energizes the
heating elements in the seat cushion and back. When
the sensor input indicates the correct temperature
set point has been achieved, the SHIM de-energizes
the N-FET. The SHIM will continue to cycle the
N-FET as needed to maintain the temperature set
point.
The SHIM will automatically turn off the heating
elements if it detects a short or an open in the heat-
ing element or a sensor out of range. These condi-
tions will also cause the SHIM to notify the occupant
of the failure via flashing the heated seat switch
LED’s as discussed later.
Switched battery power to the SHIM is supplied by
the heated seat relay mounted to the seat cushion
frame with the SHIM under the right front seat. The
battery feed is protected by a circuit breaker located
in the junction block.
Following are general descriptions of the major
components in the heated seat system. Refer to
8W-63 - Power Seat With Heated Seats in Group 8W
- Wiring Diagrams for complete circuit descriptions
and diagrams.
DESCRIPTION AND OPERATION
HEATED SEAT SWITCH
The heated seat switch assembly is located on the
center console where the ashtray is normally located
(Fig. 1). The two momentary, two-directional rocker
switches, one switch for each front seat, provide a
resistor-multiplexed signal to the Seat Heat Interface
Module (SHIM). Each switch has center NEUTRAL,
and momentary LO and HI positions so that both the
driver and the front seat passenger can select a pre-
ferred seat heating mode.
Each switch has two telltales (LED’s) which indi-
cate the mode of the heater of the respective seat.
8N - 8
ELECTRICALLY HEATED SYSTEMS
XJ
The switches also have LED’s which provide back-
lighting when the ignition switch is in the ON posi-
tion. The LED’s cannot be repaired. If the LED is
faulty, the individual switch must be replaced.
SEAT HEAT INTERFACE MODULE
The Seat Heat Interface Module (SHIM) is an elec-
tronic microprocessor controlled device designed to
operate the electric seat heater elements. The SHIM
is located under the right front seat cushion. Inputs
to the module include the console mounted resistor
multiplexed switch signals, seat cushion temperature
sensors, a relay-switched battery feed, and a ground.
The SHIM outputs are the feed for the seat heating
elements and sensors, and the switch telltale circuits.
The SHIM cannot be repaired and, if faulty or dam-
aged, it must be replaced.
HEATED SEAT RELAY
The heated seat relay is located under the right
front seat cushion near the SHIM. Ignition and bat-
tery power is fed to the relay, which then provides a
switched battery feed to the SHIM. The heated seat
relay cannot be repaired and, if faulty or damaged, it
must be replaced.
HEATED SEAT ELEMENT and SENSOR
Two heated seat heating elements are used in each
front seat, one for the seat cushion and the other for
the seat back. The two elements for each seat are
connected in series with the SHIM.
The temperature sensor is a Negative Temperature
Coefficient (NTC) thermistor. One temperature sen-
sor is used for each seat, and it is integral to the seat
cushion heating element.
The heating elements are sewn into the seat cush-
ion cover and seat back cover assemblies, which are
serviced individually. The heating elements and tem-
perature sensor cannot be repaired and, if faulty or
damaged, the affected seat cover assembly must be
replaced. Refer to Group 23 - Body for the seat cush-
ion cover and seat back cover Removal and Installa-
tion.
DIAGNOSIS AND TESTING
HEATED SEAT SYSTEM
For circuit descriptions and diagrams, refer to 8W -
63 - Power Seat With Heated Seats in Group 8W -
Wiring Diagrams.
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS,
REFER
TO
GROUP
8M
-
PASSIVE
RESTRAINT SYSTEMS BEFORE ATTEMPTING ANY
STEERING
WHEEL,
STEERING
COLUMN,
OR
INSTRUMENT PANEL COMPONENT DIAGNOSIS OR
SERVICE. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
The heated seat system is capable of performing
some self-diagnostics. The following table depicts the
various failure modes which will be reported to the
occupant via flashing the momentary switch telltales.
The switch telltales will flash on the driver’s switch
if the failure exists in the driver’s seat portion of the
system, similarly with the passenger’s switch. The
telltale will illuminate for approximately a
1
⁄
2
second
on,
1
⁄
2
second off pulse for a duration of one minute.
This process will repeat every time the system is ini-
tiated via the switches until the problem has been
corrected.
Fig. 1 Heated Seat Switch Location
1 – ASH RECEIVER
2 – HEATED SEAT SWITCHES & BEZEL
3 – WIRE HARNESS CONNECTORS
4 – FLOOR CONSOLE
XJ
ELECTRICALLY HEATED SYSTEMS
8N - 9
DESCRIPTION AND OPERATION (Continued)
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