Service Procedures; Compass Calibration; Compass Variation Adjustment - Jeep 1996 Grand Cherokee Service Manual

8V - 4 OVERHEAD CONSOLE SYSTEMS
DIAGNOSIS AND TESTING (Continued)
(2) Measure the resistance of the temperature sen-
sor. At -40°C (-40°F), the sensor resistance is 336
kilohms. At 55°C (140°F), the sensor resistance is
2.488 kilohms. The sensor resistance should read
between these two values. If OK, go to the Sensor
Circuit Test. If not OK, replace the faulty sensor.
SENSOR CIRCUIT TEST
(1) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Unplug the temperature sensor connector and the
black 24-way BCM connector.
(2) Connect a jumper wire between the two termi-
nals in the body half of the sensor connector.
(3) Check for continuity between the sensor return
circuit and the ambient temperature sensor signal
circuit cavities of the BCM connector. There should
be continuity. If OK, go to Step 4. If not OK, repair
the open circuit as required.
(4) Remove the jumper wire from the temperature
sensor connector. Check for continuity between the
sensor return circuit cavity of the BCM connector
and a good ground. There should be no continuity. If
OK, go to Step 5. If not OK, repair the short circuit
as required.
(5) Check for continuity between the ambient tem-
perature sensor signal circuit cavity of the BCM con-
nector and a good ground. There should be no
continuity. If OK, see the Trip Computer/Compass/
Display Module diagnosis in this group. If not OK,
repair the short circuit as required.

SERVICE PROCEDURES

COMPASS VARIATION ADJUSTMENT

Variance is the difference between magnetic north
and geographic north. In some areas, the difference
between magnetic and geographic north is great
enough to cause the compass to give false readings. If
this problem occurs, the compass variance must be
set.
To set the compass variance:
(1) Using the Variance Settings map, find your
geographic location and note the zone number (Fig.
1).
(2) Turn the ignition switch to the On position. If
the compass/temperature option is not being dis-
played, momentarily depress and release the Step
button to step through the display options until you
have reaced the compass/temperature display.
(3) Depress both the U.S./Metric, and the Step but-
tons. Hold the buttons down until "VAR" appears in
the display module. This takes about five seconds.
(4) Release both of the buttons. The zone number
will appear in the display module.
Fig. 1 Variance Settings
(5) Press and release the U.S./Metric button to
step through the zone numbers, until the zone num-
ber for your area appears in the display.
(6) Press the Step button to enter this zone num-
ber into the compass unit memory.
(7) Confirm that the correct directions are now
indicated.

COMPASS CALIBRATION

CAUTION: Do not place any external magnets, such
as magnetic roof mount antennas, in the vicinity of
the compass. Do not use magnetic tools when ser-
vicing the overhead console.
The electronic compass unit features a self-cali-
brating design, which simplifies the calibration pro-
cedure. This feature automatically updates the
compass calibration while the vehicle is being driven.
This allows the compass unit to compensate for small
changes in the residual magnetism that the vehicle
may acquire during normal use. Do not attempt to
calibrate the compass near large metal objects such
as other vehicles, large buildings, or bridges.
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