2002 JEEP LIBERTY Heating system

RADIATOR PRESSURE CAP
DESCRIPTION
The cooling system cap is located on the coolant
pressure bottle. The cap construction includes; stain-
less steel swivel top, rubber seals and retainer, main
spring, and a spring loaded valve (Fig. 9).
OPERATION
The pressure cap allows the cooling system to oper-
ate at higher than atmospheric pressure which raises
the coolant boiling point, thus allowing increased
radiator cooling capacity. The pressure cap releases
pressure at some point within a range of 110 kPa  
14 kPa (16 psi   2 psi).
A spring-loaded vent valve in the center of the cap
allows the system to pressurize and depressurize
without creating a vacuum. If the valve is stuck
open, coolant will escape to the overflow hose. There
is also a gasket in the cap to seal to the top of the
filler neck.
CAUTION: Use only the pressure cap specified for
this vehicle. Use of other pressure caps can lead to
coolant loss and overheating.
DIAGNOSIS AND TESTING - RADIATOR
PRESSURE CAP
Remove cap from radiator. Be sure that sealing
surfaces are clean. Moisten rubber gasket with water
and install the cap on pressure tester (tool 7700 or
an equivalent) (Fig. 10).Operate the tester pump and observe the gauge
pointer at its highest point. The cap release pressure
should be 124 to 145 kPa (18 to 21 psi). The cap is
satisfactory when the pressure holds steady. It is also
good if it holds pressure within the 124 to 145 kPa
(18 to 21 psi) range for 30 seconds or more. If the
pointer drops quickly, replace the cap.
CAUTION: Radiator pressure testing tools are very
sensitive to small air leaks, which will not cause
cooling system problems. A pressure cap that does
not have a history of coolant loss should not be
replaced just because it leaks slowly when tested
with this tool. Add water to tool. Turn tool upside
down and recheck pressure cap to confirm that cap
needs replacement.
CLEANING
Clean the radiator pressure cap using a mild soap
and water only.
INSPECTION
Visually inspect the pressure valve gasket on the
cap. Replace cap if the gasket is swollen, torn or
worn. Inspect the area around radiator filler neck for
white deposits that indicate a leaking cap.
Fig. 9 PRESSURE CAP
1 - MAIN SPRING
2 - GASKET RETAINER
3 - STAINLESS STEEL SWIVEL TOP
4 - RUBBER SEALS
5 - SPRING LOADED VALVE
6 - COOLANT PRESSURE BOTTLE
7 - FILLER NECK
8 - OVERFLOW NIPPLEFig. 10 Pressure Testing Radiator Pressure Cap -
Typical
1 - PRESSURE CAP
2 - TYPICAL COOLING SYSTEM PRESSURE TESTER
KJENGINE7s-25

²The fuel pump is energized through the fuel
pump relay by the PCM. The fuel pump will operate
for approximately three seconds unless the engine is
operating or the starter motor is engaged.
²The O2S sensor heater element is energized via
the ASD or O2S heater relay. The O2S sensor input
is not used by the PCM to calibrate air-fuel ratio dur-
ing this mode of operation.
ENGINE START-UP MODE
This is an Open Loop mode. The following actions
occur when the starter motor is engaged.
The PCM receives inputs from:
²Battery voltage
²Engine coolant temperature sensor
²Crankshaft position sensor
²Intake manifold air temperature sensor
²Manifold absolute pressure (MAP) sensor
²Throttle position sensor (TPS)
²Camshaft position sensor signal
The PCM monitors the crankshaft position sensor.
If the PCM does not receive a crankshaft position
sensor signal within 3 seconds of cranking the
engine, it will shut down the fuel injection system.
The fuel pump is activated by the PCM through
the fuel pump relay.
Voltage is applied to the fuel injectors with the
ASD relay via the PCM. The PCM will then control
the injection sequence and injector pulse width by
turning the ground circuit to each individual injector
on and off.
The PCM determines the proper ignition timing
according to input received from the crankshaft posi-
tion sensor.
ENGINE WARM-UP MODE
This is an Open Loop mode. During engine warm-
up, the PCM receives inputs from:
²Battery voltage
²Crankshaft position sensor
²Engine coolant temperature sensor
²Intake manifold air temperature sensor
²Manifold absolute pressure (MAP) sensor
²Throttle position sensor (TPS)
²Camshaft position sensor signal
²Park/neutral switch (gear indicator signalÐauto.
trans. only)
²Air conditioning select signal (if equipped)
²Air conditioning request signal (if equipped)
Based on these inputs the following occurs:
²Voltage is applied to the fuel injectors with the
ASD relay via the PCM. The PCM will then control
the injection sequence and injector pulse width by
turning the ground circuit to each individual injector
on and off.²The PCM adjusts engine idle speed through the
idle air control (IAC) motor and adjusts ignition tim-
ing.
²The PCM operates the A/C compressor clutch
through the A/C compressor clutch relay. This is done
if A/C has been selected by the vehicle operator and
specified pressures are met at the high and low±pres-
sure A/C switches. Refer to Heating and Air Condi-
tioning for additional information.
²When engine has reached operating tempera-
ture, the PCM will begin monitoring O2S sensor
input. The system will then leave the warm-up mode
and go into closed loop operation.
IDLE MODE
When the engine is at operating temperature, this
is a Closed Loop mode. At idle speed, the PCM
receives inputs from:
²Air conditioning select signal (if equipped)
²Air conditioning request signal (if equipped)
²Battery voltage
²Crankshaft position sensor
²Engine coolant temperature sensor
²Intake manifold air temperature sensor
²Manifold absolute pressure (MAP) sensor
²Throttle position sensor (TPS)
²Camshaft position sensor signal
²Battery voltage
²Park/neutral switch (gear indicator signalÐauto.
trans. only)
²Oxygen sensors
Based on these inputs, the following occurs:
²Voltage is applied to the fuel injectors with the
ASD relay via the PCM. The PCM will then control
injection sequence and injector pulse width by turn-
ing the ground circuit to each individual injector on
and off.
²The PCM monitors the O2S sensor input and
adjusts air-fuel ratio by varying injector pulse width.
It also adjusts engine idle speed through the idle air
control (IAC) motor.
²The PCM adjusts ignition timing by increasing
and decreasing spark advance.
²The PCM operates the A/C compressor clutch
through the A/C compressor clutch relay. This is done
if A/C has been selected by the vehicle operator and
specified pressures are met at the high and low±pres-
sure A/C switches. Refer to Heating and Air Condi-
tioning for additional information.
CRUISE MODE
When the engine is at operating temperature, this
is a Closed Loop mode. At cruising speed, the PCM
receives inputs from:
²Air conditioning select signal (if equipped)
²Air conditioning request signal (if equipped)
8E - 12 ELECTRONIC CONTROL MODULESKJ
POWERTRAIN CONTROL MODULE (Continued)

HEATED SYSTEMS
TABLE OF CONTENTS
page page
HEATED MIRRORS......................... 1
WINDOW DEFOGGER....................... 3HEATED SEAT SYSTEM.................... 10
HEATED MIRRORS
TABLE OF CONTENTS
page page
HEATED MIRRORS
DESCRIPTION..........................1
OPERATION............................1DIAGNOSIS AND TESTING - HEATED
MIRRORS............................1
HEATED MIRRORS
DESCRIPTION
Vehicles equipped with the optional heated mirror
package have an electric heating grid located behind
the mirror glass of each outside rear view mirror.
The heated mirrors are controlled by the rear win-
dow defogger switch. Electrical current is directed to
the heating grid inside the mirror only when the rear
window defogger switch is in the On position.
If the outside mirror heating grids and the rear
window heating grid are all inoperative, (Refer to 8 -
ELECTRICAL/HEATED GLASS - DIAGNOSIS AND
TESTING). If the outside mirror heating grids are
inoperative, but the rear window heating grid is
operating as designed, (Refer to 8 - ELECTRICAL/
HEATED MIRRORS - DIAGNOSIS AND TESTING).
The heating grid behind each outside mirror glass
cannot be repaired and, if faulty or damaged, the
entire power mirror unit must be replaced(Refer to 8
- ELECTRICAL/POWER MIRRORS/SIDEVIEW MIR-
ROR - REMOVAL) and (Refer to 8 - ELECTRICAL/
POWER MIRRORS/SIDEVIEW MIRROR -
INSTALLATION).
OPERATION
The heated mirror is controlled by the rear window
defogger switch. The only time that the heated mir-
ror is on is when the rear window defogger is on. The
mirror should become warm to the touch.
DIAGNOSIS AND TESTING - HEATED MIRRORS
For circuit descriptions and diagrams (Refer to
Appropriate Wiring Information).
(1) Check the fuse in the junction block. If OK, go
to Step 2. If not OK, repair the shorted circuit or
component as required and replace the faulty fuse.
(2) Turn the ignition switch to the On position.
Check for battery voltage at the fuse in the junction
block. If OK, go to Step 3. If not OK, repair the open
circuit to the ignition switch as required.
(3) Disconnect and isolate the battery negative
cable. Remove the front door trim panel on the side
of the vehicle with the inoperative mirror heating
grid. Unplug the wire harness connector at the mir-
ror. Check for continuity between the ground circuit
cavity in the body half of the power mirror wire har-
ness connector and a good ground. If OK, go to Step
4. If not OK, repair the open circuit to ground as
required.
(4) Connect the battery negative cable. Turn the
ignition switch to the On position. Turn on the rear
window defogger system. Check for battery voltage at
the rear window defogger relay output circuit cavity
in the body half of the power mirror wire harness
connector. If OK, go to Step 5. If not OK, repair the
open circuit to the rear window defogger relay as
required.
KJHEATED SYSTEMS 8G - 1

WINDOW DEFOGGER
TABLE OF CONTENTS
page page
WINDOW DEFOGGER
DESCRIPTION - REAR WINDOW DEFOGGER . . 3
OPERATION - REAR WINDOW DEFOGGER....3
DIAGNOSIS AND TESTING - REAR WINDOW
DEFOGGER SYSTEM...................4
STANDARD PROCEDURE - REAR GLASS
HEATING GRID REPAIR.................4
REAR WINDOW DEFOGGER GRID
DESCRIPTION..........................5
OPERATION............................5
DIAGNOSIS AND TESTING - REAR WINDOW
DEFOGGER GRID......................5
REAR WINDOW DEFOGGER RELAY
DESCRIPTION..........................6
OPERATION............................6DIAGNOSIS AND TESTING - REAR WINDOW
DEFOGGER RELAY.....................6
REMOVAL.............................7
INSTALLATION..........................7
REAR WINDOW DEFOGGER SWITCH
DESCRIPTION..........................8
OPERATION............................8
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - REAR
WINDOW DEFOGGER SWITCH...........8
DIAGNOSIS AND TESTING - REAR HVAC
CONTROL ASSEMBLY WINDOW
DEFOGGER FUNCTION.................9
REMOVAL.............................9
INSTALLATION..........................9
WINDOW DEFOGGER
DESCRIPTION - REAR WINDOW DEFOGGER
The rear window defogger system will only operate
when the ignition switch is in the run position. When
the defogger switch is in the run position, an electric
heater grid on the rear window glass is energized.
Vehicles with the heated mirror options also have
heater grids located behind the outside rear view
mirror glass. Each of these grids produce heat to help
clear the rear window glass and outside rear view
mirrors of ice, snow, or fog.
OPERATION - REAR WINDOW DEFOGGER
The rear window defogger system is controlled by a
switch installed with the HVAC control assembly. An
amber indicator lamp in the switch button will light
to indicate when the rear window defogger system is
turned on. The HVAC control head circuitry, which
contains the defogger system timer logic, monitors
the state of the defogger switch through a hard-wired
input. The instrument cluster circuitry controls therear window defogger system through a hard-wired
control output to the rear window defogger relay. The
rear window defogger timer and logic circuitry cannot
be adjusted or repaired and, if faulty or damaged, the
HVAC control head assembly must be replaced.
The rear window defogger system will be automat-
ically turned off after a programmed time interval of
about ten minutes. After the initial time interval has
expired, if the rear window defogger switch is turned
on again during the same ignition cycle, the defogger
system will automatically turn off after about five
minutes.
The rear window defogger system will automati-
cally shut off if the ignition switch is turned to the
Off position, or it can be turned off manually by
depressing the instrument panel switch. Following
are general descriptions of the major components in
the rear window defogger system. Refer to the own-
er's manual in the vehicle glove box for more infor-
mation on the features, use and operation of the
defogger system.
KJWINDOW DEFOGGER 8G - 3

DIAGNOSIS AND TESTING - REAR WINDOW
DEFOGGER SYSTEM
For circuit descriptions and diagrams, (Refer to
Appropriate Wiring Information). The operation of
the electrically heated rear window defogger system
can be confirmed in one of the following manners:
²Turn the ignition switch to the run position.
²Set the defogger switch in the run position. The
rear window defogger operation can be checked by
feeling the rear window or outside rear view mirror
glass. A distinct difference in temperature between
the grid lines and the adjacent clear glass or the mir-
ror glass can be detected within three to four min-
utes of operation.
²Using a 12-volt DC voltmeter, contact the rear
glass heating grid terminal B (right side) with the
negative lead, and terminal A (left side) with the pos-
itive lead (Fig. 1). The voltmeter should read battery
voltage.
The above checks will confirm system operation.
Illumination of the defogger switch indicator lamp
means that there is electrical current available at the
output of the defogger relay, but does not confirmthat the electrical current is reaching the rear glass
heating grid lines.
If the defogger system does not operate, the prob-
lem should be isolated in the following manner:
(1) Confirm that the ignition switch is in the run
position.
(2) Ensure that the rear glass heating grid feed
and ground wires are connected to the glass. Confirm
that the ground wire has continuity to ground.
(3) Check the fuses in the Power Distribution Cen-
ter (PDC) and in the junction block. The fuses must
be tight in their receptacles and all electrical connec-
tions must be secure.
When the above steps have been completed and the
rear glass or outside rear view mirror heating grid is
still inoperative, one or more of the following is
faulty:
²Defogger switch
²Defogger relay
²HVAC control head circuitry
²Rear window grid lines (all grid lines would
have to be broken or one of the feed wires discon-
nected for the entire system to be inoperative)
²Outside rear view mirror heating grid.
If setting the defogger switch to the On position
produces a severe voltmeter deflection, check for a
short circuit between the defogger relay output and
the rear glass or outside rear view mirror heating
grids.
STANDARD PROCEDURE - 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. 2).
Fig. 1 REAR WINDOW DEFOGGER
1 - DEFOGGER BACKGLASS
2 - HEATED GLASS CONNECTOR9A9
3 - HINDGE MOUNTING SCREWS (2)
4 - HINDGE (LEFT SIDE)
5 - HINDGE MOUNTING SCREWS (2)
6 - HINDGE (RIGHT SIDE)
7 - HEATED GLASS CONNECTOR9B9
8 - BACKGLASS DEFOGGER GRID
8G - 4 WINDOW DEFOGGERKJ
WINDOW DEFOGGER (Continued)

(4) Connect the negative lead of the voltmeter to
the right side bus bar and touch each grid line at its
midpoint with the positive lead (Fig. 3). A reading of
approximately six volts indicates a line is good. A
reading of zero volts indicates a break in the grid
line between the midpoint of the grid line and the
left side bus bar. A reading of ten to fourteen volts
indicates a break between the midpoint of the grid
line and the right side bus bar. Move the positive
lead on the grid line towards the break and the volt-
age reading will change as soon as the break is
crossed.
REAR WINDOW DEFOGGER
RELAY
DESCRIPTION
The rear window defogger relay is a International
Standards Organization (ISO)-type relay. The rear
window defogger relay is a electromechanical device
that switches fused battery current to the rear glass
and outside mirror heating grids, and the indicator
lamp of the defogger switch, when the HVAC control
head rear window defogger timer and logic circuitrygrounds the relay coil. (Refer to 8 - ELECTRICAL/
HEATED GLASS/REAR WINDOW DEFOGGER
RELAY - DIAGNOSIS AND TESTING)
The rear window defogger relay is located in the
junction block, on the left side of the instrument
panel inboard to the center of the vehicle (just to the
left and above the brake pedal or behind the knee
blocker). The rear window defogger relay cannot be
repaired and, if faulty or damaged, it must be
replaced.
OPERATION
The ISO relay consists of an electromagnetic coil, a
resistor or diode, and three (two fixed and one mov-
able) electrical contacts. The movable (common feed)
relay contact is held against one of the fixed contacts
(normally closed) by spring pressure. When the elec-
tromagnetic coil is energized, it draws the movable
contact away from the normally closed fixed contact,
and holds it against the other (normally open) fixed
contact.
When the electromagnetic coil is de-energized,
spring pressure returns the movable contact to the
normally closed position. The resistor is connected in
parallel with the electromagnetic coil in the relay,
and helps to dissipate voltage spikes that are pro-
duced when the coil is de-energized.
DIAGNOSIS AND TESTING - REAR WINDOW
DEFOGGER RELAY
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. DISCONNECT AND ISO-
LATE THE BATTERY NEGATIVE (GROUND) CABLE,
THEN WAIT TWO MINUTES FOR THE AIRBAG SYS-
TEM CAPACITOR TO DISCHARGE BEFORE PER-
FORMING FURTHER DIAGNOSIS OR SERVICE. THIS
IS THE ONLY SURE WAY TO DISABLE THE AIRBAG
SYSTEM. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN AN ACCIDENTAL
AIRBAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
RELAY TEST
The defogger relay (Fig. 4) is located in the junc-
tion block, on the left side of the instrument panel
inboard to the center of the vehicle (just to the right
and above the brake pedal or behind the knee
blocker). 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
Fig. 3 REAR WINDOW DEFOGGER
1 - DEFOGGER BACKGLASS
2 - HEATED GLASS CONNECTOR9A9
3 - HINDGE MOUNTING SCREWS (2)
4 - HINDGE (LEFT SIDE)
5 - HINDGE MOUNTING SCREWS (2)
6 - HINDGE (RIGHT SIDE)
7 - HEATED GLASS CONNECTOR9B9
8 - BACKGLASS DEFOGGER GRID
8G - 6 WINDOW DEFOGGERKJ
REAR WINDOW DEFOGGER GRID (Continued)

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 60.7 to 80.3 ohms. If OK, go to
Step 3. If not OK, replace the faulty relay.
(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.
30 - COMMON FEED
85 - COIL GROUND
86 - COIL BATTERY
87 - NORMALLY OPEN
87A - NORMALLY CLOSED
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 HVAC control
head 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 run position.
Check for battery voltage at the cavity for relay ter-
minal 86 with the ignition switch in the run 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.
REMOVAL
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. DISCONNECT AND ISO-
LATE THE BATTERY NEGATIVE (GROUND) CABLE,
THEN WAIT TWO MINUTES FOR THE AIRBAG SYS-
TEM CAPACITOR TO DISCHARGE BEFORE PER-
FORMING FURTHER DIAGNOSIS OR SERVICE. THIS
IS THE ONLY SURE WAY TO DISABLE THE AIRBAG
SYSTEM. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN AN ACCIDENTAL
AIRBAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
(1) Disconnect and isolate the battery negative
cable.
(2) Unplug the rear window defogger relay from
the junction block.
INSTALLATION
(1) Install the rear window defogger relay by align-
ing the relay terminals with the cavities in the junc-
tion block and pushing the relay firmly into place.
(2) Connect the battery negative cable.
(3) Test the relay operation.
Fig. 4 DEFOGGER RELAY- TERMINAL LEGEND
KJWINDOW DEFOGGER 8G - 7
REAR WINDOW DEFOGGER RELAY (Continued)

REAR WINDOW DEFOGGER
SWITCH
DESCRIPTION
The rear window defogger switch is installed in the
instrument panel HVAC contol head assembly. The
momentary-type switch provides a hard-wired ground
signal to the HVAC control head each time it is
depressed. The instrument cluster rear window
defogger timer and logic circuitry responds by ener-
gizing or de-energizing the rear window defogger
relay.
OPERATION
Energizing the rear window defogger relay pro-
vides electrical current to the rear window defogger
grid and, if the vehicle is so equipped, the outside
rear view mirror heating grids. An amber indicator
lamp in the defogger switch, which lights to indicate
when the defogger system is turned On, is also pow-
ered by the defogger relay output.
The defogger switch illumination lamp and indica-
tor lamp bulbs are serviceable. The defogger switch
cannot be repaired and, if faulty or damaged the
entire HVAC control head assembly must be
replaced.
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - REAR WINDOW
DEFOGGER SWITCH
For circuit descriptions and diagrams, (Refer to
Appropriate Wiring Information).
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. DISCONNECT AND ISO-
LATE THE BATTERY NEGATIVE (GROUND) CABLE,
THEN WAIT TWO MINUTES FOR THE AIRBAG SYS-
TEM CAPACITOR TO DISCHARGE BEFORE PER-
FORMING FURTHER DIAGNOSIS OR SERVICE. THIS
IS THE ONLY SURE WAY TO DISABLE THE AIRBAG
SYSTEM. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN AN ACCIDENTAL
AIRBAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
(1) Disconnect and isolate the battery negative
cable. Remove the HVAC control head assembly from
the instrument panel and unplug the defogger switch
wire harness connector-B.
(2) Check for continuity between the ground cir-
cuit cavity of the defogger switch wire harness con-nector and a good ground. There should be
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. 5). There should be momentary
continuity as the defogger switch button is depressed,
and then no continuity. If OK, (Refer to 8 - ELEC-
TRICAL/HEATED GLASS/REAR WINDOW DEFOG-
GER SWITCH - DIAGNOSIS AND TESTING -
INSTRUMENT CLUSTER REAR WINDOW DEFOG-
GER FUNCTION) If not OK, replace the faulty
switch (Fig. 5).
(4) Check switch position continuity between:
CONTACT PINS
1 - OFF LAMPS A-1 - A-7
2 - ON MOMENTARY B-6 - B-8
3 - ILLUMINATION LAMP A-7 - A-1
4 - INDICATOR LAMP B-12 - B-7
Fig. 5 A/C HEATER CONTROL HEAD (Rear View)
1 - A/C HEATER CONTROL HEAD
2 - A/C HEATER CONTROL HEAD LIGHT
3 - REAR WINDOW DEFOGGER SWITCH AND TEMPERATURE
BLEND DOOR- CONNECTOR B (12 PIN)
4 - A/C HEATER CONTROL HEAD LIGHT
5 - MODE SELECT CONTROL
6 - BLOWER SPEED CONTROL- CONNECTOR A (7 PIN)
7 - MOUNTING SCREWS (4)
8G - 8 WINDOW DEFOGGERKJ