Buick 2010 Lucerne Owner's Manual page 214

The compass can be manually calibrated. Only calibrate
the compass in a magnetically clean and safe location,
such as an open parking lot, where driving the vehicle
in circles is not a danger. It is suggested to calibrate
away from tall buildings, utility wires, manhole covers,
or other industrial structures, if possible.
If CAL should ever appear in the DIC display, the
compass should be calibrated.
If the DIC display does not show a heading, for
example, N for North, or the heading does not change
after making turns, there may be a strong magnetic field
interfering with the compass. Interference may be
caused by a magnetic antenna mount, magnetic note
pad holder, or any other magnetic item. Turn off the
vehicle, move the magnetic item, then turn on the
vehicle and calibrate the compass.
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To calibrate the compass, use the following procedure:
1. Before calibrating the compass, check that the
compass zone is set to the variance zone in which
the vehicle is located. See Compass Variance
(Zone) Procedure earlier in this section.
Do not operate any switches such as window,
sunroof, climate controls, seats, etc. during the
calibration procedure.
2. Press the vehicle information button until
PRESS TO CALIBRATE COMPASS displays.
3. Press the set/reset button to start the compass
calibration.
4. The DIC will display CALIBRATING: DRIVE IN
CIRCLES. Drive the vehicle in tight circles at less
than 5 mph (8 km/h) to complete the calibration.
The DIC will display CALIBRATION COMPLETE
for a few seconds when the calibration is complete.
The DIC display will then return to PRESS
CALIBRATE COMPASS.
TO