Cadillac 1998 Eldorado Owner's Manual page 116

Compass Operation
Press the COMPASS switch once to turn the compass
on or off.
When the ignition and the compass feature are on,
the compass will show two character boxes for
approximately two seconds. After two seconds, the
mirror will display the compass heading.
If, after two seconds, the display does not show a
compass heading ("N' for North, for example), there
may be
a
strong magnetic field interfering with the
compass. Such interference may be caused by a
magnetic antenna mount, magnetic note pad holder
or a similar magnetic item.
Compass Variance
The mirror is set .in zone eight upon leaving the factory.
It will be necessary to adjust the compass to compensate
for compass variance if you live outside zone eight.
Under certain circumstances, as during a long distance
cross-country trip, it will be necessary to adjust for
compass variance. Compass variance is the difference
between earth's magnetic north and true geographic
north. If not adjusted to account for compass variance,
your compass could give false readings.
To adjust for compass variance:
1. Use the COMPASS button located at the bottom of
2.
Press and hold the COMPASS button until a zone
the mirror.
number appears in the display.
on the following zone map.
3. Find your current location and variance zone number
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