Chrysler RG Voyager. Manual - part 713

electric backlight (EBL), consists of two vertical bus
bars linked by a series of grid lines fired onto the
inside surface of the rear window (Fig. 1).

The EBL system is turned On or Off by a switch in

the A/C-heater control located at the center of the
instrument panel and by a rear window defogger tim-
ing circuit integral to the front control module
(FCM).

Circuit protection is provided by a 40 amp fuse

located in the integrated power module (IPM).

OPERATION

The electric backlight (EBL) system is controlled

by a momentary switch located in the A/C-heater
control on the instrument panel (Fig. 2). When the

rear window defogger switch is pressed to the On
position, the front control module (FCM) energizes
the rear window defogger (EBL) relay and battery
current is then directed through the relay and to the
rear defogger grid lines and the heated side view
mirrors (when equipped). The grid lines heat the

Fig. 1 Rear Window Defogger - Typical

1 - REAR DEFOGGER GRID
2 - REAR WINDOW

HEATED SYSTEMS

8G - 1

glass to help clear the rear window and side mirror
surfaces of fog or frost.

An amber indicator in the rear window defogger

switch will illuminate to indicate when the EBL sys-
tem is turned on. The FCM contains the EBL system
control circuitry including the timer logic.

NOTE: The EBL system turns off automatically after
10 minutes of initial operation. Each following acti-
vation cycle of the EBL system will last five min-
utes.

The EBL system will be automatically turned off

after an initial 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 EBL sys-
tem will automatically turn off after about five min-
utes. 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 pressing the rear win-
dow defogger switch a second time.

Repair of the rear window defogger grid lines, bus

bars, terminals or pigtail wires can be accomplished
using the Mopar Rear Window Defogger Repair Kit
(Part Number 04549275) or equivalent (Refer to 8 -
ELECTRICAL/HEATED

GLASS/REAR

WINDOW

DEFOGGER GRID - STANDARD PROCEDURE -
GRID LINE AND TERMINAL REPAIR).

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 electric backlight (EBL) system

can be confirmed by the following:

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

the rear window defogger switch in the On position.
The rear window defogger operation can be checked
by feeling the rear window glass surface. A distinct
difference in temperature between the grid lines and
the adjacent clear glass should 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. 3). The volt-
meter should read battery voltage. If the voltmeter
does not read battery voltage, check the following:

• Confirm that the ignition switch is in the On

position.

• Make 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.

• Check that fuse 13 (40 amp) in the integrated

power module (IPM) is OK. The fuse must be tight in
its 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 DRBIII

t scan tool to perform further diag-

nostics. Refer to Body Diagnostic Procedures.

• Rear window defogger switch in the A/C-heater

control.

• J1850 bus communication between the A/C-

heater control and the front control module (FCM).

• Rear window defogger (EBL) relay in the IPM.

• Rear window defogger control circuity in the

FCM.

• Check for a loose wire connector or a wire

pushed out of a connector.

• Rear window grid lines (all grid lines would

have to be broken, or the power feed or ground wire

Fig. 2 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 - 2

HEATED GLASS

HEATED GLASS (Continued)

not connected, for the entire heating grid to be inop-
erative).

(4) If EBL system operation has been verified but

defogger switch LED indicator does not illuminate,
replace the A/C-heater control.

(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. 4) is a

International

Standards

Organization

(ISO)-type

relay. Relays conforming to the ISO specifications
have common physical dimensions, current capaci-
ties, terminal functions and patterns. The EBL relay
is a electromechanical device that switches battery
current through a fuse in the integrated power mod-
ule (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 EBL relay is energized when the
relay coil is provided a ground path by the control
circuitry within the front control module (FCM).

The EBL relay is located in the IPM in the engine

compartment.

OPERATION

The ISO-standard rear window defogger (EBL)

relay is an electromechanical switch that uses a low
current input controlled by the front control module
(FCM) to control the high current output to the rear
window defogger grid lines. The movable, common
feed relay contact is held against the fixed, normally
closed relay contact by spring pressure. When the
electromagnetic relay coil is energized, it draws the
movable common feed relay contact away from the
fixed, normally closed relay contact and, holds it
against the fixed, normally open relay contact. This
action allows high current to flow to the rear window
defogger grid lines.

When the relay coil is de-energized, spring pres-

sure returns the movable relay contact back against
the fixed, normally closed contact point. The resistor
or diode is connected in parallel with the relay coil,
and helps to dissipate voltage spikes and electromag-
netic interference that can be generated as the elec-
tromagnetic field of the relay coil collapses.

The EBL relay cannot be repaired and, if faulty or

damaged, it must be replaced. Refer to the appropri-
ate wiring information for diagnosis and testing of
the ISO-standard relay and for complete rear window
defogger (EBL) wiring diagrams.

REMOVAL

(1) Disconnect and isolate the negative battery

cable.

(2) Remove the cover from the integrated power

module (IPM) (Fig. 5) located in the engine compart-
ment.

NOTE: Refer to the fuse and relay layout map on
the inside of the IPM cover for EBL relay location.

Fig. 3 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. 4 Rear Window Defogger (EBL) Relay

HEATED GLASS

8G - 3

HEATED GLASS (Continued)

(3) Remove the EBL relay from the IPM.

INSTALLATION

NOTE: Refer to the fuse and relay layout map on
the inside of the IPM cover for EBL relay location.

(1) Position the EBL relay into the proper recepta-

cle of the integrated power module (IPM).

(2) Align the EBL relay terminals with the termi-

nal cavities in the IPM receptacle and push down
firmly on the relay until the terminals are fully
seated.

(3) Install the cover onto the IPM.
(4) Reconnect the negative battery cable.

REAR WINDOW DEFOGGER
SWITCH

DESCRIPTION

The switch for the rear window defogger (EBL)

system is integrated into the A/C-heater control,
which is located in the center of the instrument
panel (Fig. 6). When the rear window defogger switch
is activated, the A/C-heater control requests the front
control module (FCM) to operate the rear window
defogger (EBL) relay.

When the EBL relay is activated, current is

directed to the rear defogger grid lines and the
heated side view mirrors (if equipped). The grid lines
heat the glass to help clear the surface of fog or frost.

OPERATION

An LED indicator will illuminate when the rear

window defogger switch is activated. When the
switch is activated, the A/C-heater control requests
the front control module (FCM) to operate the rear
window defogger (EBL) relay. The EBL relay controls
the current flow to the grids of the rear window
defogger and to the heated side view mirrors, when
equipped.

NOTE: The EBL system turns off automatically after
10 minutes of initial operation. Each following acti-
vation cycle of the EBL system will last five min-
utes.

The EBL system will initially be on for approxi-

mately ten minutes or until the rear window defog-
ger switch or the ignition switch is turned off. After
the initial time interval has expired, if the defogger
switch is turned On again during the same ignition
cycle, the EBL system will automatically turn off
after about five minutes.

The rear window defogger switch and the rear win-

dow defogger LED indicator cannot be repaired and,
if faulty or damaged, the A/C-heater control must be
replaced (Refer to 24 - HEATING & AIR CONDI-
TIONING/CONTROLS/A/C HEATER CONTROL -
REMOVAL).

Fig. 5 Rear Window Defogger (EBL) Relay

1 - INTEGRATED POWER MODULE (IPM)
2 - REAR WINDOW DEFOGGER (EBL) RELAY
3 - FRONT CONTROL MODULE (FCM)

Fig. 6 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 GLASS

REAR WINDOW DEFOGGER RELAY (Continued)

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