Jeep XJ. Manual - part 136

REAR GLASS HEATING GRID

For circuit descriptions and diagrams, refer to

8W-48 - Rear Window Defogger in Group 8W - Wir-
ing Diagrams. To detect breaks in the grid lines, the
following procedure is required:

(1) Turn the ignition switch to the On position. Set

the defogger switch in the On position. The indicator
lamp should light. If OK, go to Step 2. If not OK, see
the Defogger Relay diagnosis in this group.

(2) Using a 12-volt DC voltmeter, contact the ver-

tical bus bar on the right side of the vehicle with the
negative lead. With the positive lead, contact the ver-
tical bus bar on the left side of the vehicle. The volt-
meter should read battery voltage. If OK, go to Step
3. If not OK, repair the open circuit to the defogger
relay as required.

(3) With the negative lead of the voltmeter, contact

a good body ground point. The voltage reading should
not change. If OK, go to Step 4. If not OK, repair the
circuit to ground as required.

(4) Connect the negative lead of the voltmeter to

the right side bus bar and touch each grid line at
midpoint C with the positive lead. A reading of
approximately six volts indicates a line is good. A
reading of zero volts indicates a break in the grid
line between midpoint C and the left side bus bar. A
reading of ten to fourteen volts indicates a break
between midpoint C and the right side bus bar. Move
the positive lead on the grid line towards the break
and the voltage reading will change as soon as the
break is crossed.

DEFOGGER SWITCH

For circuit descriptions and diagrams, refer to

8W-48 - Rear Window Defogger in Group 8W - Wir-
ing Diagrams.

WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS,

REFER

GROUP

PASSIVE

RESTRAINT SYSTEMS BEFORE ATTEMPTING ANY
STEERING

WHEEL,

STEERING

COLUMN,

INSTRUMENT PANEL COMPONENT DIAGNOSIS OR
SERVICE. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.

(1) Disconnect and isolate the battery negative

cable. Remove the accessory switch bezel from the
instrument panel and unplug the defogger switch
wire harness connector.

(2) Check for continuity between the ground cir-

cuit cavity of the defogger switch wire harness con-
nector

and

good

ground.

There

should

continuity. If OK, go to Step 3. If not OK, repair the
open circuit as required.

(3) Check for continuity between the ground cir-

cuit terminal and the rear window defogger switch
sense circuit terminal on the back of the defogger
switch housing (Fig. 2). There should be momentary
continuity as the defogger switch button is depressed,
and then no continuity. If OK, see the diagnosis for
the Instrument Cluster in this group. If not OK,
replace the faulty switch.

DEFOGGER RELAY

WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS,

REFER

GROUP

PASSIVE

RESTRAINT SYSTEMS BEFORE ATTEMPTING ANY
STEERING

WHEEL,

STEERING

COLUMN,

INSTRUMENT PANEL COMPONENT DIAGNOSIS OR
SERVICE. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.

RELAY TEST

The defogger relay (Fig. 3) is located in the junc-

tion block, on the right cowl side inner panel below
the instrument panel in the passenger compartment.
Remove the defogger relay from the junction block to
perform the following tests:

(1) A relay in the de-energized position should

have continuity between terminals 87A and 30, and
no continuity between terminals 87 and 30. If OK, go
to Step 2. If not OK, replace the faulty relay.

(2) Resistance between terminals 85 and 86 (elec-

tromagnet) should be 75

6 10 ohms. If OK, go to

Step 3. If not OK, replace the faulty relay.

SWITCH POSITION

CONTINUITY BETWEEN

OFF

LAMPS

MOMENTARY 1 AND 2

ILLUMINATION LAMP

1 AND 4

INDICATOR LAMP

1 AND 3

Fig. 2 Defogger Switch Continuity

8N - 4

ELECTRICALLY HEATED SYSTEMS

DIAGNOSIS AND TESTING (Continued)

(3) Connect a battery to terminals 85 and 86.

There should now be continuity between terminals
30 and 87, and no continuity between terminals 87A
and 30. If OK, see the Relay Circuit Test in this
group. If not OK, replace the faulty relay.

RELAY CIRCUIT TEST

(1) The relay common feed terminal cavity (30) is

connected to battery voltage and should be hot at all
times. If OK, go to Step 2. If not OK, repair the open
circuit to the PDC fuse as required.

(2) The relay normally closed terminal (87A) is

connected to terminal 30 in the de-energized position,
but is not used for this application. Go to Step 3.

(3) The relay normally open terminal (87) is con-

nected to the common feed terminal (30) in the ener-
gized position. This terminal supplies battery voltage
to the rear glass and outside rear view mirror heat-
ing grids and the defogger switch indicator lamp.
There should be continuity between the cavity for
relay terminal 87 and the rear window defogger relay
output circuit cavities of the rear glass heating grid
connector, both outside rear view mirror heating grid
connectors, and the defogger switch connector at all
times. If OK, go to Step 4. If not OK, repair the open
circuit(s) as required.

(4) The coil ground terminal (85) is connected to

the electromagnet in the relay. This terminal is pro-
vided with ground by the instrument cluster rear
window defogger timer and logic circuitry to energize
the defogger relay. There should be continuity to
ground at the cavity for relay terminal 85 when the
defogger switch is turned On. However, with the
defogger relay removed, the defogger switch indicator
lamp will not light to show that the defogger system

is turned On. Be certain that you depress the defog-
ger switch at least twice to confirm that the system
is turned on during this test. If OK, go to Step 5. If
not OK, repair the open circuit to the instrument
cluster as required.

(5) The coil battery terminal (86) is connected to

the electromagnet in the relay. It is connected to
fused ignition switch output voltage and should be
hot when the ignition switch is in the On position.
Check for battery voltage at the cavity for relay ter-
minal 86 with the ignition switch in the On position.
If OK, see the diagnosis for Instrument Cluster in
this group. If not OK, repair the open circuit to the
fuse in the junction block as required.

INSTRUMENT CLUSTER

Before performing this test, complete the Defogger

Switch and the Defogger Relay tests as described in
this group. For circuit descriptions and diagrams,
refer to 8W-48 - Rear Window Defogger in Group 8W
- Wiring Diagrams.

WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS,

REFER

GROUP

PASSIVE

RESTRAINT SYSTEMS BEFORE ATTEMPTING ANY
STEERING

WHEEL,

STEERING

COLUMN,

INSTRUMENT PANEL COMPONENT DIAGNOSIS OR
SERVICE. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.

(1) Disconnect and isolate the battery negative

cable. Remove the defogger relay from the junction
block and unplug the defogger switch wire harness
connector.

(2) Remove the instrument cluster from the instru-

ment panel. Refer to Instrument Cluster in Group 8E
- Instrument Panel Systems for the procedures.

(3) Check for continuity between the rear window

defogger switch sense circuit cavity of the right
instrument cluster wire harness connector (connector
B) and a good ground. There should be no continuity.
If OK, go to Step 4. If not OK, repair the short circuit
as required.

(4) Check for continuity between the rear window

defogger switch sense circuit cavities of the right
instrument cluster wire harness connector (connector
B) and the defogger switch wire harness connector.
There should be continuity. If OK, go to Step 5. If not
OK, repair the open circuit as required.

(5) Check for continuity between the rear window

defogger relay control circuit cavity of the right
instrument cluster wire harness connector (connector
B) and a good ground. There should be no continuity.
If OK, go to Step 6. If not OK, repair the short circuit
as required.

TERMINAL LEGEND

NUMBER

IDENTIFICATION

COMMON FEED

COIL GROUND

COIL BATTERY

NORMALLY OPEN

87A

NORMALLY CLOSED

Fig. 3 Defogger Relay

ELECTRICALLY HEATED SYSTEMS

8N - 5

DIAGNOSIS AND TESTING (Continued)

(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

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

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

(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

ELECTRICALLY HEATED SYSTEMS

8N - 7

REMOVAL AND INSTALLATION (Continued)

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