OPERATION
When the rear window defogger button is
depressed to the On position, current is directed to
the rear defogger grid lines and the heated power
mirrors (if equipped). The heated grid lines heat the
glass to help clear the rear window and side mirror
surfaces of fog or frost.
The electric backlight (EBL) system is controlled
by a momentary switch located in the A/C-heater
control on the instrument panel. A yellow indicator in
the switch will illuminate to indicate when the sys-
tem is turned on. The integrated power module (IPM)
contains the EBL system control circuitry.
NOTE: The rear window defogger turns off automat-
ically after approximately 10 minutes of initial oper-
ation. Each following activation cycle of the
defogger system will last approximately five min-
utes.
The EBL system will be automatically turned off
after a programmed time interval of about ten min-
utes. After the initial time interval has expired, if the
defogger switch is turned on again during the same
ignition cycle, the defogger system will automatically
turn off after about five minutes.
The EBL 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 defogger
switch a second time.
DIAGNOSIS AND TESTING
ELECTRIC BACKLIGHT (EBL) SYSTEM
NOTE: Illumination of the defogger switch indicator
lamp means that there is electrical current available
at the output of the rear window defogger logic cir-
cuitry, but does not confirm that the electrical cur-
rent is reaching the rear glass heating grid lines.
NOTE: For circuit descriptions and diagrams of the
rear window defogger system, refer to 8W - WIRING
DIAGRAM INFORMATION.
Operation of the electrical backlight (EBL) system
can be confirmed by the following:(1) Turn the ignition switch to the On position. Set
the defogger switch in the On position. The rear win-
dow defogger operation can be checked by feeling the
rear window glass. A distinct difference in tempera-
ture between the grid lines and the adjacent clear
glass can be detected within three to four minutes of
operation.
(2) If a temperature difference is not detected, use
a 12-volt DC voltmeter and contact the rear glass
heating grid terminal B with the negative lead, and
terminal A with the positive lead (Fig. 2). The volt-
meter should read battery voltage. If the voltmeter
does not read battery voltage, check the following:
²Confirm that the ignition switch is in the On
position.
²Make sure that the rear glass heating grid feed
wire and ground wire are connected to the terminals.
Confirm that the ground wire has continuity to
ground.
²Check that fuse 13 (40 amp) in the integrated
power module (IPM) is OK. The fuse must be tight in
it's receptacle and all electrical connections must be
secure.
(3) When the above steps have been completed and
the rear glass heating grid is still inoperative, one or
more of the following is faulty. It may be necessary to
connect a DRBIIItscan tool to perform further diag-
nostics. Refer to Body Diagnostic Procedures.
²Rear window defogger switch in the A/C-heater
control.
²J1850 bus communication between the A/C-
heater control and the front control module (FCM).
²Rear window defogger (EBL) relay in the IPM.
²Rear window defogger (EBL) relay control circu-
ity in the IPM.
²Check for a loose wire connector or a wire
pushed out of a connector.
²Rear window grid lines (all grid lines would
have to be broken, or the power feed or ground wire
not connected, for the entire heating grid to be inop-
erative).
(4) If the system operation has been verified but
defogger switch LED indicator does not illuminate,
replace the A/C-heater control.
8G - 2 HEATED GLASSRS
HEATED GLASS (Continued)
(5) If broken defogger grid lines are suspected, use
a 12-volt DC voltmeter and contact terminal B with
the negative lead and each rear glass heating grid
line at it's mid-point with the positive lead. The volt-
meter should read approximately 6 volts at each grid
line mid-point C. If the voltmeter does not read
approximately 6 volts, repair the open grid line(s)
(Refer to 8 - ELECTRICAL/HEATED GLASS/REAR
WINDOW DEFOGGER GRID - STANDARD PROCE-
DURE).
REAR WINDOW DEFOGGER
RELAY
DESCRIPTION
The rear window defogger (EBL) relay (Fig. 3) is a
International Standards Organization (ISO)-type
relay. Relays conforming to the ISO specifications
have common physical dimensions, current capaci-
ties, terminal patterns, and terminal functions. The
rear window defogger relay is a electromechanical
device that switches battery current through a fuse
in the integrated power module (IPM) to the rear
window defogger grid and switches battery current
through a positive thermal coefficient (PTC) in the
IPM to the outside mirror heating grids. The relay isenergized when the relay coil is provided a ground
path by the rear window defogger relay control in the
front control module (FCM).
The rear window defogger (EBL) relay is located in
the IPM in the engine compartment. See the fuse
and relay layout map on the inner surface of the
cover of the IPM for rear window defogger relay iden-
tification and location.
The rear window defogger (EBL) relay cannot be
adjusted or repaired and, if damaged or faulty, it
must be replaced.
OPERATION
The ISO-standard rear window defogger (EBL)
relay consists of an electromagnetic coil, a resistor or
diode, and three (two fixed and one movable) electri-
cal contacts. The movable (common feed) relay con-
tact 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.
Refer to the appropriate wiring information for
diagnosis and testing of the EBL relay and for com-
plete EBL system wiring diagrams.
Fig. 2 Grid Line Test
1 - VOLTMETER
2 - VOLTAGE FEED (A)
3 - FEED WIRE
4 - MID-POINT (C)
5 - HEATED WINDOW GRID
6 - GROUND WIRE
7 - GROUND (B)Fig. 3 Rear Window Defogger (EBL) Relay
RSHEATED GLASS8G-3
HEATED GLASS (Continued)
REMOVAL
(1) Disconnect and isolate the negative battery
cable.
(2) Remove the cover from the integrated power
module (IPM) (Fig. 4).
NOTE: Refer to the fuse and relay layout map on
the inner surface of the cover of the IPM for rear
window defogger (EBL) relay identification and
location.
(3) Remove the EBL relay from the IPM.
INSTALLATION
NOTE: Refer to the fuse and relay map on the inner
surface of the cover of the integrated power module
(IPM) for rear window defogger (EBL) relay identifi-
cation and location.
(1) Position the EBL relay into the proper recepta-
cle in the IPM.
(2) Align the EBL relay terminals with the termi-
nal cavities in the IPM receptacle.
(3) Push down firmly on the EBL relay until the
terminals are fully seated in the terminal cavities.
(4) Install the cover onto the IPM.
(5) Reconnect the negative battery cable.
REAR WINDOW DEFOGGER
SWITCH
DESCRIPTION
The switch for the EBL system is integrated into
the A/C-heater control located in the center of the
instrument panel (Fig. 5).
When the rear window defogger switch is turned to
the ON position, current is directed to the rear defog-
ger grid lines and the heated power mirrors (if
equipped). The heated grid lines heat the glass to
help clear the surface of fog or frost.
OPERATION
Depressing the rear window defogger switch ener-
gizes the A/C-heater control module which then
requests the front control module (FCM) to activate
the rear window defogger (EBL) relay via the com-
munication bus. The EBL relay controls the current
to flow to the grids of the rear window defogger and
the heated power side view mirrors. The EBL relay
will be on for approximately 10 minutes or until the
control switch or ignition is turned off. An amber
indicator lamp in the defogger switch illuminates to
indicate when the EBL system is On.
The rear window defogger switch and indicator
lamp cannot be repaired and, if faulty or damaged,
the entire A/C-heater control must be replaced.
Fig. 4 Rear Window Defogger (EBL) Relay
1 - INTEGRATED POWER MODULE (IPM)
2 - REAR WINDOW DEFOGGER (EBL) RELAY
3 - FRONT CONTROL MODULE (FCM)
Fig. 5 A/C-Heater Control - Typical
1 - TRIM BEZEL
2 - INFRARED TEMPERATURE SENSOR
3 - A/C REQUEST SWITCH
4 - EBL/HEATED MIRROR SWITCH
5 - FRONT WINDOW DEFROSTER SELECTOR
8G - 4 HEATED GLASSRS
REAR WINDOW DEFOGGER RELAY (Continued)
HORN
TABLE OF CONTENTS
page page
HORN SYSTEM
DESCRIPTION..........................1
OPERATION............................1
DIAGNOSIS AND TESTING
HORN SYSTEM........................1
HORN
DIAGNOSIS AND TESTING
HORN...............................3REMOVAL.............................4
INSTALLATION..........................4
HORN SWITCH
DESCRIPTION..........................4
HORN SYSTEM
DESCRIPTION
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAG, REFER TO ELECTRICAL, RESTRAINTS FOR
SAFETY PRECAUTIONS. DISCONNECT THE NEGA-
TIVE CABLE FROM THE BATTERY BEFORE SER-
VICING COMPONENTS INVOLVING THE AIRBAG
SYSTEM. ACCIDENTAL DEPLOYMENT OF AIRBAG
AND PERSONAL INJURY CAN RESULT.
The horn circuit consists of a horn switch, clock-
spring, horn relay, horns and Integrated Power Mod-
ule (IPM). The horn switch is a membrane switch
located in the airbag trim cover. The horns are
located forward of the left front wheel behind the
bumper fascia.
OPERATION
The horn relay plugs into the Integrated Power
Module (IPM) which is located in the engine com-
partment. For circuit information and component
locations, refer to the appropriate wiring information.
The wiring information includes wiring diagrams,
proper wire and connector repair procedures, details
of wire harness routing and retention, connector pin-
out information and location views for the various
wire harness connectors, splices and grounds.
The horns will not function if the switch is
ªCLOSEDº for more than 30 seconds. Once the
switch is ªOPENº, a 20±30 second delay will occur
before the horns are functional again.
DIAGNOSIS AND TESTING
HORN SYSTEM
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, REFER TO ELECTRICAL, RESTRAINTS
BEFORE ATTEMPTING ANY STEERING WHEEL,
STEERING COLUMN, OR INSTRUMENT PANEL
COMPONENT DIAGNOSIS OR SERVICE. FAILURE
TO TAKE THE PROPER PRECAUTIONS COULD
RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT
AND POSSIBLE PERSONAL INJURY.
Refer to Horn System Test below. If the horn does
not sound, check horn fuse located in the Integrated
Power Module (IPM). If the fuse is blown, replace
with the correct fuse. If the horns fail to sound and
the new fuse blows when depressing the horn switch,
a short circuit in the horn or the horn wiring
between the fuse terminal and the horn is responsi-
ble, or a defective horn switch allowed the horn to
burn out is responsible.
If the fuse is OK, test horn relay.
If the relay is OK, test horn.
CAUTION: Continuous sounding of horn may
cause horn failure.
Should the horn sound continuously, unplug the
horn relay from IPM.
Refer to the appropriate wiring information.
RSHORN8H-1
CONDITION POSSIBLE CAUSE CORRECTION
(6) CLOCKSPRING
INOPERATIVE.(6) REPLACE CLOCKSPRING.
(7) FRONT CONTROL
MODULE INOPERATIVE.(7) REFER TO ELECTRONIC CONTROL
MODULES/FRONT CONTROL MODULE.
FUSE BLOWS WHEN HORN SOUNDS (1) SHORT CIRCUIT IN
HORN OR HORN WIRING.(1) REMOVE HORN RELAY, CHECK
FOR SHORTED HORN OR HORN
WIRING. DISCONNECT HORN WIRE
HARNESS TO ISOLATE SHORT AND
REPAIR AS NECESSARY.
(2) CLOCKSPRING
INOPERATIVE.(2) REPLACE CLOCKSPRING.
FUSE BLOWS WITHOUT BLOWING
HORN(1) SHORT CIRCUIT. (1) REMOVE RELAY, INSTALL NEW
FUSE, IF FUSE DOES NOT BLOW
REPLACE HORN RELAY. IF FUSE
BLOWS WITH RELAY REMOVED,
CHECK FOR SHORT TO GROUND
WITH OHMMETER ON CIRCUIT
BETWEEN TERMINALS 30 & 86 AND
THE FUSE TERMINAL. REPAIR AS
NECESSARY.
(2) CLOCKSPRING
INOPERATIVE.(2) REPLACE CLOCKSPRING.
HORN
DIAGNOSIS AND TESTING
HORN
HORN
(1) Disconnect wire connector at horn.
(2) Using a voltmeter, connect one lead to ground
terminal and the other lead to the positive wire ter-
minal (Fig. 1).
(3) Depress the horn switch, battery voltage
should be present.
(4) If no voltage, refer toHORNS WILL NOT
SOUND. If voltage is OK, go to step Step 5.
(5) Using ohmmeter, test ground wire for continu-
ity to ground.
(6) If no ground repair as necessary.
(7) If wires test OK and horn does not sound,
replace horn.
HORNS SOUND CONTINUOUSLY
CAUTION: Continuous sounding of horns may
cause relay to fail.
The horn switch (membrane) sometimes can be the
cause without the switch being depressed.(1) Remove the horn relay from the intelligent
power module.
(2)
Using a continuity tester, test continuity from the
X3 cavity of the horn relay to ground. Refer to the
appropriate wiring information. The wiring information
includes wiring diagrams, proper wire and connector
repair procedures, details of wire harness routing and
retention, connector pin-out information and location
views for the various wire harness connectors, splices
and grounds.
(a)If continuity is detected, proceed to step Step 3.
(b) If NO continuity, replace the horn relay.
(3) Remove the airbag trim cover from the steering
wheel and disengage horn connector.
(4) Install horn relay into Integrated Power Mod-
ule (IPM).
(a)
If horn does not sound, replace airbag trim
cover.
(b) If horn sounds, repair grounded X3 circuit
from IPM to clockspring in the steering column.
HORNS WILL NOT SOUND
Check horn fuse#8intheIPM. If fuse is blown,
check for a shorted switch in the airbag module. and
refer to FUSE BLOWN section. If fuse is OK, refer to
FUSE OK section.
FUSE BLOWN
(1) Verify condition of battery terminals and volt-
age, (Refer to 8 - ELECTRICAL/BATTERY SYSTEM
RSHORN8H-3
HORN SYSTEM (Continued)
HEADLAMP
DIAGNOSIS AND TESTING - HEADLAMP
When a vehicle experiences problems with the
headlamp system, verify the condition of the battery
connections, fuses, charging system, headlamp bulbs,
wire connectors, relay, high beam switch, dimmer
switch, and headlamp switch. Refer to the appropri-
ate wiring information.
Each vehicle is equipped with various lamp assem-
blies. A good ground is necessary for proper lighting
operation. Grounding is provided by the lamp socketwhen it comes in contact with the metal body, or
through a separate ground wire.
When changing lamp bulbs check the socket for
corrosion. If corrosion is present, clean it with a wire
brush.
When it is necessary to remove components to ser-
vice another, it should not be necessary to apply
excessive force or bend a component to remove it.
Before damaging a trim component, verify hidden
fasteners or captured edges are not holding the com-
ponent in place.
HEADLAMP DIAGNOSIS
CONDITION POSSIBLE CAUSES CORRECTION
HEADLAMPS ARE DIM
WITH ENGINE IDLING
OR IGNITION TURNED
OFF.1. Loose or corroded battery
cables.1. Clean and secure battery cable clamps and
posts.
2. Loose or worn generator drive
belt.2. Adjust or replace generator drive belt.
3. Charging system output too low. 3. Test and repair charging system, refer to
Electrical, Charging
4. Battery has insufficient charge. 4. Test battery state-of-charge, refer to
Electrical, Battery System.
5. Battery is sulfated or shorted. 5. Load test battery, refer to Electrical, Battery
System.
6. Poor lighting circuit Z343/Z344-
ground.6. Test for voltage drop across Z343/Z344-
ground locations, refer to Electrical, Wiring
Diagram Information.
HEADLAMP BULBS
BURN OUT
FREQUENTLY.1. Integrated Power Module (IPM)
not controlling voltage.1. Test and repair Integrated Power Module.
2. Loose or corroded terminals or
splices in circuit.2. Inspect and repair all connectors and splices.
Refer to Electrical, Wiring Information.
HEADLAMPS ARE DIM
WITH ENGINE
RUNNING ABOVE IDLE.1. Charging system output too low. 1. Test and repair charging system, refer to
Electrical, Wiring Information.
2. Poor lighting circuit Z343/Z344-
ground.2. Test for voltage drop across Z343/Z344-
ground locations, refer to Electrical, Wiring
Information.
3. High resistance in headlamp
circuit.3. Test amperage draw of headlamp circuit.
RSLAMPS/LIGHTING - EXTERIOR8L-11
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the three retaining screws.
(3) Disconnect the central wiring harness connec-
tor from the headlamp unit.
(4) Remove the headlamp unit from the vehicle by
rotating the turn signal area out and towards the
center of the vehicle.
INSTALLATION
(1) Connect the wiring harness to the headlamp
unit's central connector.
(2) Place the headlamp unit in the headlamp unit
pocket in front end first by placing the inboard side
behind the fascia. Complete the installation by rotat-
ing the turn signal area of the headlamp into place.
(3) Place headlamp unit into headlamp unit pocket
in front end.
(4) Install the three retaining screws.
(5) Connect the battery negative cable.
(6) Verify vehicle and system operation.
LICENSE LAMP
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove two screws (Fig. 18).
(3) Twist bulb socket and remove (Fig. 19).
(4) Pull bulb from socket.
INSTALLATION
(1) Push bulb into socket.
(2) Install socket into lamp.
(3) Install two screws.
(4) Reconnect the battery negative cable.
MULTI-FUNCTION SWITCH
DESCRIPTION - TURN SIGNAL SYSTEM
The turn signals are actuated with a lever on
Multi-Function Switch, located on the left side of the
steering wheel. The signals are automatically turned
off by a canceling cam (two lobes molded to the clock
spring mechanism). The cam comes in contact with
the cancel actuator on the turn signal (multi-func-
tion) switch assembly. Either cam lobe, pushing on
the cancel actuator, returns the switch to the OFF
position. The multi-function switch is a resistive
MUX switch that feeds inputs to the BCM.
OPERATION - TURN SIGNAL SYSTEM
Lane change signaling is actuated by applying par-
tial turn signal stalk movement toward the direction
desired until the indicator lamps flashes in the
instrument cluster. When the switch stalk is released
the stalk will spring back into the neutral position
turning OFF the turn signal.
With the ignition switch ON and the turn signal
switch stalk actuated left or right, current flows
through the:
²Multi-function switch
²Body Control Module
²Integrated Power Module (IPM)
²Turn indicator lamp
²Front and rear turn signal bulbs.
A chime will sound after the vehicle has traveled a
distance of approximately 1.0 mile and a speed of 15
mph, with the turn signal ON.
Fig. 18 LICENSE PLATE LAMP UNITS
1 - SCREW
2 - LICENSE PLATE LAMP
Fig. 19 LICENSE PLATE LAMP - REMOVE/INSTALL
1 - LICENSE PLATE LAMP UNIT
2 - BULB
RSLAMPS/LIGHTING - EXTERIOR8L-17
HEADLAMP UNIT - EXPORT (Continued)
The compass unit will also compensate for magne-
tism the vehicle may acquire during normal use.
However, avoid placing anything magnetic directly on
the roof of the vehicle. Magnetic mounts for an
antenna, a repair order hat, or a funeral procession
flag can exceed the compensating ability of the com-
pass unit if placed on the roof panel. The use of mag-
netic tools on the fasteners that hold the overhead
console assembly to the roof header can also affect
compass operation. If the compass operation is
erratic and roof magnetization is suspected (Refer to
8 - ELECTRICAL/OVERHEAD CONSOLE - STAN-
DARD PROCEDURE - COMPASS DEMAGNETIZ-
ING).
DESCRIPTION - TEMPERATURE
All overhead consoles include temperature informa-
tion. The temperature displays the outside ambient
temperature in whole degrees. The temperature dis-
play can be toggled from Fahrenheit to Celsius by
selecting the desired U.S./Metric option from the cus-
tomer programmable features. The displayed temper-
ature is not an instant reading of conditions, but an
average temperature. It may take the temperature
display several minutes to respond to a major tem-
perature change, such as driving out of a heated
garage into winter temperatures.
When the ignition switch is turned to the Off posi-
tion, the last displayed temperature reading stays in
the electronic control modules (CMTC, EVIC) mem-
ory. When the ignition switch is turned to the On
position again, the electronic module will display the
memory temperature for one minute; then update the
display to the current average temperature reading
within five minutes.
The temperature function is supported by an ambi-
ent temperature sensor. The sensor is mounted near
the front and center of the vehicle, and is hard wired
to the Powertrain Control Module (PCM). The PCM
sends temperature status messages to the module
over the Programmable Communication Interface
(PCI) data bus circuit.
DIAGNOSIS AND TESTING
OVERHEAD CONSOLE
Any diagnosis of the overhead console should
begin with the use of the DRB IIItdiagnostic
tool. For information on the use of the DRB
IIIt, refer to the appropriate Diagnostic Proce-
dures information.If the problem with the overhead console is an
inaccurate or dashed (- -) display, refer to SELF-DI-
AGNOSTIC TEST. If the problem with the overhead
console is incorrect Vacuum Fluorescent Display
(VFD) dimming levels, use a DRB IIItscan tool and
the proper diagnostic procedures information to test
for the correct dimming message inputs being
received from the Body Control Module (BCM) or
Front Control Module (FCM) over the Programmable
Communications Interface (PCI) data bus circuit. If
the problem is a no-display condition, use the follow-
ing procedures.
Inspect the related wiring harness connectors for
broken, bent, pushed out, or corroded terminals.
Refer to the appropriate wiring information.
(1) Check the fused B(+) fuse in the integrated
power module. If OK, go to Step 2. If not OK, repair
the shorted circuit or component as required and
replace the faulty fuse.
(2) Check for battery voltage at the fused B(+) fuse
in the integrated power module. If OK, go to Step 3.
If not OK, repair the open fused B(+) circuit to the
fused B(+) fuse in the integrated power module as
required.
(3) Check the fused ignition switch output (run/
start) fuse in the integrated power module. If OK, go
to Step 4. If not OK, repair the shorted circuit or
component as required and replace the faulty fuse.
(4) Turn the ignition switch to the On position.
Check for battery voltage at the fused ignition switch
output (run/start) fuse in the integrated power mod-
ule. If OK, go to Step 5. If not OK, repair the open
fused ignition switch output (run/start) circuit to the
ignition switch as required.
(5) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Remove the overhead console. Check for continuity
between the ground circuit cavity of the roof wire
harness connector for the electronics module and a
good ground. There should be continuity. If OK, go to
Step 6. If not OK, repair the open ground circuit as
required.
(6) Connect the battery negative cable. Check for
battery voltage at the fused B(+) circuit cavity of the
roof wire harness connector for the electronics mod-
ule. If OK, go to Step 7. If not OK, repair the open
fused B(+) circuit to the fused B(+) fuse in the inte-
grated power module as required.
(7) Turn the ignition switch to the On position.
Check for battery voltage at the fused ignition switch
output (run/start) circuit cavity of the roof wire har-
ness connector for the electronics module. If OK,
refer to SELF-DIAGNOSTIC TEST. If not OK, repair
the open fused ignition switch output (run/start) cir-
cuit to the fuse in the integrated power module as
required.
RSOVERHEAD CONSOLE8M-3
OVERHEAD CONSOLE (Continued)