Jeep 200 Cherokee, Service Manual

Page: 528 / 2119

(3) Connect a battery to terminals 85 and 86.
There should now be continuity between terminals
30 and 87, and no continuity between terminals 87A
and 30. If OK, see the Relay Circuit Test in this
group. If not OK, replace the faulty relay.
RELAY CIRCUIT TEST
(1) The relay common feed terminal cavity (30) is
connected to battery voltage and should be hot at all
times. If OK, go to Step 2. If not OK, repair the open
circuit to the PDC fuse as required.
(2) The relay normally closed terminal (87A) is
connected to terminal 30 in the de-energized position,
but is not used for this application. Go to Step 3.
(3) The relay normally open terminal (87) is con-
nected to the common feed terminal (30) in the ener-
gized position. This terminal supplies battery voltage
to the rear glass and outside rear view mirror heat-
ing grids and the defogger switch indicator lamp.
There should be continuity between the cavity for
relay terminal 87 and the rear window defogger relay
output circuit cavities of the rear glass heating grid
connector, both outside rear view mirror heating grid
connectors, and the defogger switch connector at all
times. If OK, go to Step 4. If not OK, repair the open
circuit(s) as required.
(4) The coil ground terminal (85) is connected to
the electromagnet in the relay. This terminal is pro-
vided with ground by the instrument cluster rear
window defogger timer and logic circuitry to energize
the defogger relay. There should be continuity to
ground at the cavity for relay terminal 85 when the
defogger switch is turned On. However, with the
defogger relay removed, the defogger switch indicator
lamp will not light to show that the defogger system
is turned On. Be certain that you depress the defog-
ger switch at least twice to confirm that the system
is turned on during this test. If OK, go to Step 5. If
not OK, repair the open circuit to the instrument
cluster as required.
(5) The coil battery terminal (86) is connected to
the electromagnet in the relay. It is connected to
fused ignition switch output voltage and should be
hot when the ignition switch is in the On position.
Check for battery voltage at the cavity for relay ter-
minal 86 with the ignition switch in the On position.
If OK, see the diagnosis for Instrument Cluster in
this group. If not OK, repair the open circuit to the
fuse in the junction block as required.
INSTRUMENT CLUSTER
Before performing this test, complete the Defogger
Switch and the Defogger Relay tests as described in
this group. For circuit descriptions and diagrams,
refer to 8W-48 - Rear Window Defogger in Group 8W
- Wiring Diagrams.
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS,
REFER TO GROUP 8M - PASSIVE
RESTRAINT SYSTEMS BEFORE ATTEMPTING ANY
STEERING
WHEEL, STEERING COLUMN, OR
INSTRUMENT PANEL COMPONENT DIAGNOSIS OR
SERVICE. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
(1) Disconnect and isolate the battery negative
cable. Remove the defogger relay from the junction
block and unplug the defogger switch wire harness
connector.
(2) Remove the instrument cluster from the instru-
ment panel. Refer to Instrument Cluster in Group 8E
- Instrument Panel Systems for the procedures.
(3) Check for continuity between the rear window
defogger switch sense circuit cavity of the right
instrument cluster wire harness connector (connector
B) and a good ground. There should be no continuity.
If OK, go to Step 4. If not OK, repair the short circuit
as required.
(4) Check for continuity between the rear window
defogger switch sense circuit cavities of the right
instrument cluster wire harness connector (connector
B) and the defogger switch wire harness connector.
There should be continuity. If OK, go to Step 5. If not
OK, repair the open circuit as required.
(5) Check for continuity between the rear window
defogger relay control circuit cavity of the right
instrument cluster wire harness connector (connector
B) and a good ground. There should be no continuity.
If OK, go to Step 6. If not OK, repair the short circuit
as required.
TERMINAL LEGEND
NUMBER IDENTIFICATION
30 COMMON FEED
85 COIL GROUND
86 COIL BATTERY
87 NORMALLY OPEN
87A NORMALLY CLOSED
Fig. 3 Defogger Relay
XJ
ELECTRICALLY HEATED SYSTEMS 8N - 5
DIAGNOSIS AND TESTING (Continued)