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REAR WINDOW DEFOGGER
8N - 1
REAR WINDOW DEFOGGER
C O N T E N T S
Page
REPAIR PROCEDURES (GRID LINES,
TERMINALS, AND PIGTAILS) . . . . . . . . . . . . . 3
GENERAL INFORMATION
The electrically heated rear w i n d o w defogger is
available on Ramcharger w i t h sunscreen glass only.
The system consists o f a rear w i n d o w w i t h t w o ver-
t i c a l bus bars a n d a series of electrically connected
g r i d lines baked on the inside surface.
C i r c u i t protection for the heated g r i d circuit is pro-
vided by a 18 gauge fusible l i n k w i r e located i n t h e
engine compartment. T h e relay c i r c u i t is protected
by a 20 amp fuse, located i n the fuse block.
W h e n the rear window defogger s w i t c h is placed i n
the O N position, c u r r e n t is directed t o rear w i n d o w
g r i d lines. T h e heated g r i d lines i n t u r n heat t h e
rear window t o clear the surface o f fog or snow.
Page
SERVICE PROCEDURES
4
TEST PROCEDURES . . . . . . . . . . . . . . . . . . . . . . 1
CAUTION: Grid lines can be damaged or scraped
off with sharp instruments. Care should be taken in
cleaning the glass or removing foreign materials,
decals or stickers. Normal glass cleaning solvents
or hot water used with rags or toweling is recom-
mended.
SYSTEM DESCRIPTION
CONTROL
SWITCH/TIMER
RELAY
MODULE
The control s w i t c h and t i m e r relay are integrated
i n t o a single panel mounted assembly. A c t u a t i n g t h e
switch energizes t h e electronic t i m i n g c i r c u i t w h i c h
allows current to flow t h r o u g h t h e g r i d system for
approximately 10 minutes, or u n t i l either t h e control
switch or i g n i t i o n is t u r n e d off. A n i n d i c a t i n g l a m p
i l l u m i n a t e s a lens i n l a i d i n the control switch.
T E S T P R O C E D U R E S
INDEX
Page
Page
Control Switch/Timer Module Test
. . . . . . . . . . . . .
2
System Test
. 1
Rear Window Grid Lines Test . . . . . . . . . . . . . . . . . 2
SYSTEM TEST
Electrically heated rear window defogger operation
can be checked in-vehicle i n the f o l l o w i n g manner:
(1) T u r n the i g n i t i o n O N .
(2) T u r n rear window defogger control switch O N .
(3) M o n i t o r vehicle voltmeter. W i t h t h e control
switch O N , a distinct needle deflection should be
noted.
(4) T h e rear window defogger operation can be
checked by feeling the glass. A d i s t i n c t difference i n
temperature between
t h e g r i d lines a n d adjacent
clear glass can be detected i n 3 to 4 m i n u t e s of oper-
ation.
(5) U s i n g a D C voltmeter (Fig. 1), contact t e r m i n a l
" B " w i t h the negative lead (passenger side), and ter-
m i n a l " A " w i t h t h e positive lead (driver side). T h e
voltmeter should read 10-14 volts.
VOLTMETER
Fig. 1 Grid Line Test
O n l y steps (3) and (4) or (5) above w i l l c o n f i r m sys-
t e m operation. Indicator l i g h t i l l u m i n a t i o n
means
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