Dodge RAM TRUCK 1500 1995 Service Manual page 371

8C - 4 OVERHEAD CONSOLE B R
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 occurs, the variance must be set.
To set the variance:
(1) Using the map in Fig. 3, find your geographic
location and note the zone number.
Fig. 3 Variance Settings
(2) Turn ignition switch to the ON position.
(3) Depress both the US/METRIC and COMP/
TEMP buttons. Hold down until VAR is displayed.
This takes about 5 seconds.
(4) Release both buttons.
(5) Press the US/METRIC button to step through
the numbers until the zone number for your area ap­
pears in the display.
(6) Press the COMP/TEMP button to enter this
zone number into compass unit memory.
(7) Confirm correct directions are indicated.
COiPASS CALIBRATION
CAUTION: D O NOT place any external magnets
such as magnetic roof mount antennas, in the vicin­
ity of the compass. DO NOT use magnetic tools
when servicing the overhead console.
The compass features a self-calibrating design,
which simplifies the calibration procedure. This fea­
ture automatically updates the compass calibration
while the vehicle is being driven. This takes into ac­
count small changes in residual magnetism the vehi­
cle may acquire during normal use. Do not attempt
to calibrate the compass near large metal objects
such as other vehicles, large buildings or bridges.
Whenever the compass is calibrated manually,
the variation number must also be reset. See
Variation Adjustment Procedure, in this group.
Calibrate the compass manually as follows:
(1) Start the engine.
(2) Depress both the US/METRIC and COMP/
TEMP buttons. Hold down until CAL is displayed.
This takes about 10 seconds and appears about 5 sec­
onds after VAR is displayed.
(3) Release both buttons.
(4) Drive vehicle on a level surface that is away
from large metal objects through 3 or more complete
circles in not less than 48 seconds. The CAL message
will disappear to indicate that the compass is now
calibrated.
If CAL message remains in display, either
there is excessive magnetism near the compass
or the unit is faulty. Repeat the demagnetizing
and calibration procedures at least one more
time.
If the wrong direction is still indicated, the
area selected may be too close to a strong mag­
netic field. Repeat the calibration procedure in
another location.
COMPASS DEMAGNETIZING
The tool used to degauss or demagnetize the roof
panel is the Miller Tool 6029. Equivalent units must
be rated as continuous duty for 110/115 volts and
60Hz. They must also have a field strength of over
350 gauss at 1/4-inch beyond the tip of the probe.
The degaussing tool is used to demagnetize the roof
panel, as follows:
(1) Be sure the ignition switch is in the OFF posi­
tion before you begin the demagnetizing procedure.
(2) Place an 8-1/2 X 11 inch piece of paper, oriented
lengthwise from front to rear, on the center line of
the roof at the windshield header (Fig. 4). The pur­
pose of the paper is to protect the roof panel from
scratches and define the area to be demagnetized.
(3) Plug in the degaussing tool, while keeping the
tool at least 2 feet away from the compass unit.