rela ys wh ich a llows battery cu rren t to flow to the
rear win dow defogger grid lin es. The h eated grid
lin es heat the rear gla ss to help clea r the rear win-
dow surfaces of fog or frost.
The electric backlight (EBL) system is controlled
by the EBL t iming circuity, which is integra l to t he
rear window defogger m odule. A yellow indica tor in
the switch will illuminate to indicate wh en t he 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 aut omat ically turned off
after a program med time int erva l of a bout t en min-
utes. After the initial t ime int erva l ha s expir ed, if t he
rear win dow defogger switch is pr essed to th e On
position again during the sam e ignition cycle, the
EBL system will au tomat ically turn off aft er about
five min utes.
The EBL system will automa tically shut off if the
ign ition switch is turned to the Off position, or it can
be tu rned off manu ally by pressing t he defogger
switch a second t ime.
DI AGN OSI S AN D T EST I N G
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.
Operat ion of the electrical backlight (EBL) system
can be confirmed by the followin g:
(1) Turn t he ignit ion switch t o t he On position. Set
the r ear window defogger switch in the On position .
The rea r window defogger oper ation ca n be checked
by feeling the rea r window glass. A dist inct differen ce
in te mp e rature b etwe en the grid lines and the ad ja-
cent clea r glass should be detect ed within three to
four minutes of operation.
(2) If a tempera ture differen ce is not detect ed, use
a 12-volt DC voltm eter and cont act t he rear glass
heating grid terminal B with the negative lead, and
term inal A with the positive lead (Fig. 2). Th e volt-
meter shou ld read ba ttery volt age. If the volt meter
does not rea d batt ery voltage, ch eck t he followin g:
• Con firm t hat the ignition switch is in the On
position .
• Ma ke sure tha t the rea r gla ss heating gr id feed
wires and ground wir es are connected t o the win dow
term inals. Con firm that t he ground wires h ave conti-
nuity t o ground.
• Ch eck that fuse 7 (15 a mp) in fu se block #1 and
fuse 10 (30 amp) in t he fuse/r elay block a re OK. The
fuses must be tight in there recept acles and all elec-
trical connect ions must be secure.
(3) When the above steps have been com pleted and
the rea r glass heating grid is still in operative, one or
more of the following is fau lty.
• Rear win dow defogger swit ch in the instru ment
panel.
• Rear win dow defogger (EBL) relays in the fu se/
rela y block.
• Rear window defogger (E BL) relay control circu-
ity in th e rea r window defogger m odu le.
• Ch eck for a loose wir e connector or a wire
pu sh ed out of a conn ector.
• Rear window grid lines (all grid lines would
have to be broken, or the power feed or grou nd wir e
not connected, for the entire hea tin g grid to be inop-
erat ive).
(4) If the system oper ation h as been verified but
the defogger switch indicator does not illuminate,
check for volta ge at t he defogger in dicator fr om the
rear win dow defogger module when t he defogger
switch is activated. If power is present, replace th e
rear window defogger switch.
(5) If broken defogger grid lines are suspected, use
a 12-volt DC voltmeter a nd contact terminal B with
the n egat ive lead an d each rear glass hea tin g gr id
lin e a t it’s mid-point with th e posit ive lead. The volt-
meter shou ld read approxima tely 6 volts a t ea ch gr id
lin e mid-point C. If th e voltm eter does not read
approximately 6 volts, r epair t he open gr id line(s)
(Refer t o 8 - ELECTRICAL/HEATE D GLASS/RE AR
WINDOW DEFOGGER GRID - STANDARD PROCE-
DURE ).
8G - 2 H EAT ED GL AS S VA
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