DaimlerChrysler LH New Yorker 1994, Электронное руководство по обслуживанию

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(5) 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.
(6) Steps (3) and (4) or (5) above will confirm system
operation. Indicator light illumination means that there
is power available at the output of the relay only, and
does not necessarily verify system operation.
(7) If turning the switch ON produced no distinct
current draw on the ammeter the problem should be
isolated in the following manner:
(a) Confirm the ignition switch is ON.
(b) Ensure that the heated rear glass feed wire is
connected to the terminal or pigtail and that the
ground wire is in fact grounded.
(c) Ensure that the fusible link and control circuit
fuse is operational and all electrical connections are
secure.
(8) When the above steps have been completed and
the system is still inoperative, one or more of the
following is defective:
(a) Control switch or timer relay.
(b) Rear window grid lines, all grid lines would
have to be broken or one of the feed wires are not
connected for the system to be inoperative.
(9) If turning the switch ON produces severe volt-
meter deflection, the circuit should be closely checked
for a shorting condition.
(10) If the system operation has been verified but
indicator bulb does not light, service the A/C heater or
ATC controls.
(11) For detailed wiring information, refer to group
8W, Wiring Diagrams.
GRID TEST
The horizontal grid lines and vertical bus bar lines
printed and fired on inside surface of rear window
glass (Fig. 4) comprise an electrical parallel circuit.
The electrically conductive lines are composed of a
silver-ceramic material which when fired on glass
becomes bonded to the glass and is highly resistant to
abrasion. It is possible, however, that a break may
occur in an individual grid line resulting in no cur-
rent flow through the line. To detect breaks in grid
lines the following procedure is required:
(1) Turn ignition ON and turn control switch to
ON. The indicator light should come on.
(2) Using a DC voltmeter with 0-15 volt range,
contact terminal B with negative lead of voltmeter.
With positive lead of voltmeter, contact terminal A
(Fig. 4). The voltmeter should read 10-14 volts. A
lower voltage reading indicates a poor ground connec-
tion.
(3) With negative lead of voltmeter, contact a good
body ground point. The voltage reading should not
change.
(4) Connect negative lead of voltmeter to terminal B
and touch each grid line at Mid-Point with Positive lead.
A reading of approximately 6 volts indicates a line is
good. A reading of 0 volts indicates a break in line
between Mid-Point C and terminal A. A reading of 10-14
volts indicates a break between Mid-Point C and termi-
nal B. Move toward break and voltage will change as
soon as break is crossed (Figs. 4 and 5).
CONTROL SWITCH AND TIMER RELAY TEST
Vehicles with ATC heater will have to be tested
with DRB. The Body Diagnostic Procedures Manual
will have to be used.
Vehicles with manual A/C heater, the control switch
and timer relay may be tested in the vehicle or on the
bench.
Fig. 4 Grid Line Test
Fig. 5 Systems Electrical Circuit
8N - 2 REAR WINDOW DEFOGGER