Chrysler 1998 Voyager Service Manual page 506

8N - 2 ELECTRICALLY HEATED SYSTEMS
DIAGNOSIS AND TESTING (Continued)
Fig. 3 HVAC Rear Window Defogger Switch
DIAGNOSIS AND TESTING
SYSTEM TEST
Electrically heated rear window defogger or the
heated windshield wiper deicer operation can be
checked on the vehicle in the following manner:
(1) Turn the ignition switch to the ON position.
(2) Using a ammeter on the battery, turn the rear
defogger control switch to the ON position, a distinct
increase in amperage draw should be noted.
(3) The rear window defogger or the heated wind-
shield wiper deicer operation can be checked by feel-
ing the glass. A distinct difference in temperature
between the grid lines and adjacent clear glass can
be detected in 3 to 4 minutes of operation.
(4) Using a DC voltmeter (Fig. 4) contact terminal
B with the negative lead, and terminal A with the
positive lead. The voltmeter should read 10-14 volts.
(5) Indicator light illumination means that there is
power available at the switch only and does not nec-
essarily verify system operation.
(6) If turning the defogger switch ON, no distinct
current draw on the ammeter the problem should be
isolated in the following manner:
• Confirm that ignition switch is ON.
• Ensure that the heated rear window or the
heated windshield wiper deicer feed pigtail is con-
nected to the wiring harness and that the ground
pigtail is in fact grounded.
• Ensure that the proper fuse in the Junction
Block is OK.
(7) When the above steps have been completed and
the system is still inoperative, one or more of the fol-
lowing is defective:
• HVAC switch
• Rear window defogger relay in the relay bank.
• Check for loose connector or a wire pushed out
of connector.
• Rear window or the windshield grid lines (all
grid lines would have to be broken, or one of the feed
pigtails not connected to the bus bar, for no ammeter
deflection).
(8) If turning the switch ON produces severe volt-
meter deflection, the circuit should be closely checked
for a shorting condition.
(9) If the system operation has been verified but
indicator LED does not light, replace switch.
(10) For detailed wiring information, refer to
Group 8W, Wiring Diagrams.
Fig. 4 Grid Line Test
GRID LINE TEST
The horizontal grid lines and vertical bus bar lines
printed and baked on inside surface of the window
glass makes up an electrical parallel circuit. The
electrically conductive lines are composed of a silver
ceramic material which when baked on glass
becomes bonded to the glass and is highly resistant
to abrasion. It is possible, however, that a break may
exist or occur in an individual grid line resulting in
no current flow through the line. To detect breaks in
grid lines, the following procedure is required:
(1) Turn ignition and rear window defogger control
switch ON. The indicator light should come on.
(2) Using a DC voltmeter with 0-15 volt range,
contact vertical bus bar connecting grid lines on pas-
senger side of vehicle at terminal A with negative
lead of voltmeter (Fig. 4). With positive lead of volt-
meter, contact vertical bus bar on driver side of vehi-
cle at terminal B. The voltmeter should read 10-14
volts.
NS