relays which allows battery current to flow to the
rear window defogger grid lines. The heated grid
lines heat the rear glass to help clear the rear win-
dow surfaces of fog or frost.
The electric backlight (EBL) system is controlled
by the EBL timing circuity, which is integral to the
rear window defogger module. A yellow indicator in
the switch will illuminate to indicate when the EBL
system is turned on.
NOTE: The EBL system turns off automatically after
approximately 10 minutes of initial operation. Each
following activation cycle of the EBL system will
last approximately five minutes.
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
rear window defogger switch is pressed to the On
position again during the same ignition cycle, the
EBL 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 pressing 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
EBL 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 rear window defogger switch in the On position.
The rear window defogger operation can be checked
by feeling the rear window glass. A distinct difference
in temperature between the grid lines and the adja-
cent 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. 2). 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
wires and ground wires are connected to the window
terminals. Confirm that the ground wires have conti-
nuity to ground.
•
Check that fuse 7 (15 amp) in fuse block #1 and
fuse 10 (30 amp) in the fuse/relay block are OK. The
fuses must be tight in there receptacles and all elec-
trical 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.
•
Rear window defogger switch in the instrument
panel.
•
Rear window defogger (EBL) relays in the fuse/
relay block.
•
Rear window defogger (EBL) relay control circu-
ity in the rear window defogger module.
•
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
not connected, for the entire heating grid to be inop-
erative).
(4) If the system operation has been verified but
the defogger switch indicator does not illuminate,
check for voltage at the defogger indicator from the
rear window defogger module when the defogger
switch is activated. If power is present, replace the
rear window defogger switch.
(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).
8G - 2
HEATED GLASS
VA
