Jeep J-10 Series 1982 Technical & Service Manual page 1206

3U-2 TAILGATE WINDOW DEFOGGER
With the control switch on the instrument panelacti
vated and ignition switch On, the relay contacts close.
The timer in the relay operates the defogger for 8 to 12
minutes, depending on the ambient temperature, or un
til the control switch or ignition switch is turned Off.
The pilot lamp indicates system operation.
NOTE: The defogger switch and the electric tailgate
window switeh are serviced as an assembly.
TESTING
Switch Test
(1) Turn ignition switch On and press defogger
switch.
(2) Disconnect optional equipment wiring harness
at connector under dash. Connect a 12-volt test lamp
from purple wire (89) to a good ground (fig. 3U-1). Test
lamp should light.
(3) Shut off defogger switch and test lamp should
not light.
(4) To test indicator light, disconnect orange wire
from lamp. Connect jumper wire from accessory termi
nal of new fuse panel to orange wire. With ignition
switch turned to Accessory position, the lamp should
light.
Ftolay Tut
NOTE: Terminals on the relay are labeled X, L and P.
(1) Attach negative lead of voltmeter to ground.
Probe red w/tr wire (X-terminal) with voltmeter posi
tive lead. Voltmeter should indicate battery voltage re
gardless of ignition switch position.
If no voltage is indicated, operate the tailgate window.
(The tailgate window and rear window defogger are fed
by the same wire.) If the window operated, the wire
between the window switch and relay is open.
(2) Probe orange wire (L-terminal) with voltmeter
positive lead. No voltage should be indicated.
(3) Turn ignition switch to On or Accessory posi
tion. Voltmeter should indicate voltage. If no voltage is
indicated, relay is defective, or is not receiving voltage
from purple wire (P-terminal).
If relay activates properly, it should remain energized
8 to 12 minutes before opening (ignition switch must
remain On). If the time period is too short or excessively
long, relay is defective.
(4) If relay did not energize, connect jumper wire to
known good 12-volt source in tailgate and probe relay P-
terminal. If relay clicks when probed, trace purple wire
for open or short.
If relay does not click when probed by jumper, check
relay ground and repair if necessary. If relay still fails to
operate, it is defective.
Grid Tut
When a grid is inoperable due to an open circuit, the
area of glass normally cleared by that grid will remain
fogged or iced until adequately warmed by the adjacent
grids. Use the following procedure to locate a broken
grid.
(1) With engine running at idle, press tailgate win
dow defogger switch. Defogger lamp should light, in
dicating defogger operation.
NOTE: The feed wire is connected to the right side
(passenger side) of the window and the ground con
nection is on the left side of the window.
(2) Use 12vdc voltmeter and contact positive lead of
voltmeter to right side (feed) vertical bus element on
inside surface of glass. Contact negative lead to left side
(ground) bus element (fig. 3U-2). Voltage drop indicated
on meter should be 11 to 13 volts. Connect negative lead
of voltmeter to good ground—meter reading should not
change.
GROUND
BROKEN
GRID
GROUND
VOLTMETER 12-VOLT
DC
CENTERLINE OF GLASS
BROKEN
GRIO
FEED
12-VOLT
0-VOLT
70504
Rg. 3U-2 Vcltmttir ConBtctleos lodVoltigi Drop for Grid Coittstilty
(3) Keep negative lead connected to ground. Use
positive lead and carefully contact each grid at approx
imate centerline of window.
(4) Voltage drop of one-half full amount, approx
imately six volts, indicates good grid or closed circuit.
(5) Full voltage drop of 12 volts at centerline in
dicates break in grid between positive lead and ground.
(6) No voltage drop (0 volts) at centerline indicates
break in grid between centerline and voltage source or
feed.
(7) The exact location of the break can then be pin
pointed by moving the positive lead to the left or right
along the grid until an abrupt change in the voltage
reading is noticed.