JEEP CHEROKEE 1994 Service Repair Manual

REAR WINDOW DEFOGGER
CONTENTS
page page
GENERAL.............................. 1
XJ .................................... 4YJ .................................... 4
GENERAL
INDEX
page page
Diagnosis............................... 2
Rear Window Defogger Grid Repair........... 2Rear Window Defogger Grid Test............. 1
Switch Testing............................ 2
Using heating elements bonded to the rear window
glass, the rear defogger will clear condensation, frost
and light snow coverings from the rear window.
The horizontal grid lines and vertical bus bar lines,
printed and baked on inside surface of the rear win-
dow glass, comprise an electrical circuit. The electri-
cally conductive lines are composed of a silver-
ceramic material which when baked on glass
becomes bonded to the glass and is highly resistant
to abrasion.
The electrical current required to produce the heat
in the grid is supplied through a relay and driver op-
erated switch. When the switch is momentarily de-
pressed, the relay senses a voltage change. This
voltage change causes the relay to change state and
complete a circuit to energize the relay. Once the re-
lay energizes, the contacts close connecting the grid
to battery power.
On the XJ, the power circuit to the grid is pro-
tected by the 25 amp, #18 fuse in the fuse box.
Power for fuse #18 comes from the power distribu-
tion center, fuse #F10. Power for the relay is pro-
tected by the 20 amp, #8 fuse located in the fuse box.
On the YJ, the grid is protected by a 25 amp #6
fuse, located in the fuse box. Power for the relay is
protected by 15 amp #9 fuse, located in the fuse box.
To defog the rear window, momentarily depress the
rocker switch. A light on the rocker switch will illu-
minate indicating that the defogger is operating.
If the ignition switch is ON the first activation of
the defog/defrost feature will last for 10 minutes.
Succeeding activations will last for 5 minutes unless
the ignition switch is turned OFF; then it will recy-
cle back to 10 minutes for the first activation.To stop defogger operation, momentarily push the
switch a second time.
CAUTION: Use care when washing the inside of the
rear window to prevent damage to the defogger
heating elements. Use a soft cloth and a mild wash-
ing solution. Wiping motions should be parallel to
the heating elements. Also, keep all objects a safe
distance from the window to prevent damaging the
heating elements.
REAR WINDOW DEFOGGER GRID TEST
It is possible, that a break may exist or occur in an
individual grid line resulting in no current flow
through the line. When a grid has an open circuit,
the area of glass normally cleared by that grid re-
mains fogged or iced unless, and until it is cleared by
the adjacent grids.
With the engine running at idle, push the rear
window defogger switch to the ON position and re-
lease. The pilot lamp in the rocker switch should
light, indicating defogger operation.
Using a 12-volt DC voltmeter, contact the positive
lead to the feed side vertical bus element on the in-
side surface of the glass. Contact the negative lead to
the ground side bus element. Meter should read be-
tween 11 and 13 volts. Connect the negative lead of
the voltmeter to a good ground; the meter reading
should be constant.
Keep the negative lead connected to ground. Use
the positive lead and carefully contact each grid at
the approximate centerline of the window.
JREAR WINDOW DEFOGGER 8N - 1

A voltage drop of one-half the full amount, approx-
imately 6 volts, indicates a good grid or closed cir-
cuit.
A voltage drop of 12 volts at the centerline indi-
cates a break in the grid between the positive volt-
meter lead and the ground.
No voltage drop (0 volts) at the centerline indicates
a break in the grid between the centerline and the
voltage source or lead.
The exact location of the break can be pinpointed
by moving positive voltmeter lead to the left or right
along grid. An abrupt change in the voltage reading
will be noticed. The break is at that point in the
grid.
REAR WINDOW DEFOGGER GRID REPAIR
Locate the broken or open grid.
Use the grid repair kit (available as a service part)
by using the following procedure:
(1) Mark the location of the broken or open grid on
the exterior surface of the glass using a suitable
marking pencil.
(2) Lightly rub the area to be repaired (inside the
rear window) using fine steel wool. Clean the area
with alcohol.
(3) Attach two strips of masking tape to the inside
surface of the rear window (above and below the
break in the grid) (Fig. 1).
(4) Remove package separator clamp and mix plas-
tic conductive epoxy thoroughly. Fold in half and cut
center corner to dispense epoxy.
(5) Apply conductive epoxy through slit in mask-
ing tape. Overlap both ends of the break.
(6) For a terminal or pigtail replacement, mask ad-
jacent areas so epoxy can be extended onto line and
buss bar. Apply a thin layer of epoxy to area where
terminal was fastened and to adjacent line.
(7) Apply a thin layer of conductive epoxy on ter-
minal and place terminal on desired location. To pre-
vent terminal from moving while the epoxy is curing,
it must be wedged or clamped.
(8) Carefully remove masking tape from grid line.
(9) Allow epoxy to cure 24 hours at room tempera-ture or use heat gun with a 260É-371ÉC (500É-700ÉF)
range for 15 minutes. Hold gun approximately
254mm (10 inches) from repaired area.
(10) After conductive epoxy is properly cured re-
move wedge from terminal and check out operation
of rear window defogger. Do not attach connectors
until curing is complete.
WARNING: REPAIR KIT MAY CAUSE SKIN OR EYE
IRRITATION.
CONTAINS EPOXY RESIN AND AMINE TYPE
HARDENER, HARMFUL IF SWALLOWED. AVOID
CONTACT WITH SKIN AND EYES. FOR SKIN,
WASH AFFECTED AREAS WITH SOAP AND WA-
TER. DO NOT TAKE INTERNALLY. IF TAKEN
INTERNALLY, INDUCE VOMITING; CALL A
PHYSICIAN IMMEDIATELY. IF IN CONTACT
WITH EYES, FLUSH WITH PLENTY OF WATER.
USE WITH ADEQUATE VENTILATION. DO NOT
USE NEAR FIRE OR FLAME. CONTENTS CON-
TAIN 3% FLAMMABLE SOLVENTS.
WARNING: KEEP OUT OF REACH OF CHIL-
DREN.
SWITCH TESTING
DIAGNOSIS
Refer to Group 8W - Wiring Diagrams for a com-
plete circuit diagram.
BATTERY, IGNITION & FUSES
²Check fuses #6 and #9 (YJ), or #8 and #18 fuse
(XJ). Replace as required.
²If the fuses are not blown check the battery side of
#18 fuse (XJ) or fuse #6 (YJ) for battery voltage. If
battery voltage is not present replace the Maxi fuse
located in the power distribution center.
²Check the ignition side of fuse #9 (YJ), fuse #8
(XJ) for battery voltage. If battery voltage is not
present check for an open from the ignition switch.
DEFOGGER SWITCH
Defogger switch connector separated from de-
fogger switch; turn ignition switch to ON for
voltage tests; turn ignition switch to OFF for re-
sistance tests
²Measure voltage at defogger switch connector ter-
minal D. The meter should read approximately 5
volts momentarily. If not, repair open from relay.
²Refer to switch diagram for resistance tests. If val-
ues do not match, replace defogger switch.
DEFOGGER RELAY
Defogger relay connector separated from de-
fogger relay; turn ignition switch to ON for volt-
age tests; turn ignition switch to OFF for
resistance tests
Fig. 1 Grid Line Repair (Typical)
8N - 2 REAR WINDOW DEFOGGERJ

²Measure voltage at relay connector terminal 4.
The meter should read battery voltage. If not, repair
open to fuse #18 (XJ), or fuse #9 (YJ).
²Measure voltage at relay connector terminal 5.
The meter should read battery voltage. If not, repair
open from #8 fuse XJ, or fuse #6 YJ.
²Measure resistance between relay connector termi-
nal 1 and left side (driver's side) of defogger grid.
The meter should read zero ohms. If not, repair open
between relay connector and left side of defogger
grid.
²Measure resistance between relay connector termi-
nal 2 and a clean chassis ground. The meter should
read zero ohms. If not, repair open between relay
connector and ground.
²Connect relay connector and measure voltage at
terminal 3. The meter should read approximately 5volts. If not, replace defogger relay.
INDICATOR LAMP
Refer to switch diagram for resistance tests. If val-
ues do not match, replace defogger switch.
DEFOGGER GRID
Turn defogger switch to ON; turn ignition
switch to ON for voltage tests; turn ignition
switch to OFF for resistance tests
²Measure voltage at left side (driver's side) of defog-
ger grid. The meter should read battery voltage. If
not, repair open from defogger relay.
²Measure resistance for right side of defogger grid
to a clean chassis ground. The meter should read
zero ohms. If not, repair open between right side of
defogger grid and ground.
JREAR WINDOW DEFOGGER 8N - 3

XJ
REAR WINDOW DEFOGGER SWITCH
REPLACEMENT
(1) Remove the instrument panel bezel; see 8E-In-
strument Panel and Gauges section for the proce-
dure.
(2) Remove the switch housing panel.
(3) Unplug the switch connector. Slightly depress
the switch mounting tabs and remove the switch.
REAR DEFOGGER RELAY
The rear defogger relay is in the relay center. The
relay center is located on the lower instrument panel
trim cover just right of the steering column.
(1) Remove the rear defogger relay (red) from the
relay center (Fig. 2).
(2) To install the relay, reverse the removal proce-
dures.
YJ
REAR WINDOW DEFOGGER SWITCH
REPLACEMENT
(1) Remove 6 shroud screws (Fig. 3).
(2) Slide shroud toward the steering wheel.
(3) Remove 3 screws (Fig. 4).
(4) Unplug the connector from the defogger switch.
(5) Squeeze the ends of the switch to release the
plastic retaining fingers and push outward.
(6) To install, depress the rear window defogger
switch into the bezel until the retaining fingers lock
behind the bezel.
(7) Plug the connector on the switch.(8) Install the bezel with 3 screws.
(9) Install the shroud with 6 screws.
REAR DEFOGGER RELAY
The rear defogger relay is in the relay center. The
relay center is located on the lower instrument panel
trim cover just right of the steering column.
(1) Remove the rear defogger relay (red) from the
relay center (Fig. 2).
(2) To install the relay, reverse the removal proce-
dures.
Fig. 2 Rear Defogger Relay LocationÐXJ
Fig. 3 Instrument Shroud Removal/InstallationÐYJ
Fig. 4 Defogger SwitchÐYJ
8N - 4 REAR WINDOW DEFOGGERJ

POWER DOOR LOCKS
CONTENTS
page page
KEYLESS ENTRY........................ 8POWER LOCKS......................... 1
POWER LOCKS
INDEX
page page
Actuator Motor Stall Test.................... 6
Description.............................. 1
Diagnosing Power Door Locks............... 1
General................................. 1Liftgate Lock Cylinder Replacement............ 7
Solenoid and Latch Assembly Replacement..... 6
Switch Replacement....................... 6
GENERAL
The door lock actuators, including liftgate, are con-
trolled by two-way switches. To lock the doors, push
down on either switch. To unlock doors from inside
the vehicle push upward on either switch.
The power door locks do not lock or unlock the
doors from outside the vehicle. Insert the key into
the lock cylinder to lock or unlock each individual
door.
DESCRIPTION
The door locks are operated by reversible motors
that receive voltage from fuse #13 in the fuse panel.
Voltage is applied to the driver's side door lock
switch and the passenger's side door lock switch
through the #9 fuse. With the driver's side door lock
switch in LOCK, voltage is applied through the
switch to the door lock relay coil. The relay coil is
energized which closes the circuit from the circuit
breaker to the lock motor. The motor is grounded by
the unlock relay.
The passenger's side door lock window switch oper-
ates the same as the driver's door switch. The volt-
age and ground paths are reversed to unlock the
doors.
The power door lock operates with battery power
and, therefore, is independent of the ignition switch.
DIAGNOSING POWER DOOR LOCKS
If vehicle has Keyless Entry and the door locks op-
erate properly using door switches but do not work
with transmitter, refer to Keyless Entry in this
group.
NO DOOR LOCKS OPERATE USING DOOR
LOCK SWITCHES
(1) Inspect fuse #13. Replace if necessary. If OK,
measure voltage at battery side of fuse. There should
be 12 volts. If not, repair open from Power Distribu-
tion Center.
(2) Remove door switch and measure voltage at
terminal 1. Meter should read battery voltage. If not,
repair open to #9 fuse.
(3) The power window relays are in the relay cen-
ter. The relay center is located on the lower instru-
ment panel trim cover just right of the steering
column (Fig. 1). Remove both relays.
(4) Measure resistance between lock and unlock re-
lay terminal 4 (87A) and ground. Meter should read
zero ohms. If not, repair open to ground.
(5) Measure voltage at terminal 5 (87) of both the
lock and unlock relays. Meter should read battery
voltage. If OK, next step. If not, repair open to cir-
cuit breaker.
(6) Measure resistance at terminal 2 (85) of both
the lock and unlock relays. Meter should read zero
ohms. If not, repair open to ground.
(7) Hold driver's side switch in LOCK position.
Measure voltage at lock relay terminal 1 (86). Meter
should read battery voltage. If OK, next step. If not,
repair open to driver's side switch.
(8) Hold driver's side switch in UNLOCK position.
Measure voltage at unlock relay terminal 1 (86).
Meter should read battery voltage. If OK, next step.
If not, repair open to driver's side switch.
JPOWER DOOR LOCKS 8P - 1

(9) Hold driver's side switch in LOCK position.
Measure voltage at lock relay terminal 3 (30). Meter
should read battery voltage. If OK, next step. If not,
replace lock relay.
(10) Hold driver's side switch in UNLOCK posi-
tion. Measure voltage at unlock relay terminal 3
(30). Meter should read battery voltage. If OK, check
connections and door motor. If not, replace unlock re-
lay.
(11) Repeat procedures for passenger's side switch.
Fig. 1 Door Lock/Unlock Relays
DRIVERS DOOR POWER LOCK SWITCHÐ2-DOOR LEFT HAND DRIVE
8P - 2 POWER DOOR LOCKSJ

DRIVERS DOOR POWER LOCK SWITCHÐ2-DOOR RIGHT HAND DRIVE
JPOWER DOOR LOCKS 8P - 3

DRIVERS DOOR POWER LOCK SWITCHÐ4-DOOR
8P - 4 POWER DOOR LOCKSJ

PASSENGER DOOR LOCK SWITCH
JPOWER DOOR LOCKS 8P - 5