Pontiac 2003 Bonneville Owner's Manual page 185

Calibrating the Compass
All electronic compasses need to know the magnetic
profile of your vehicle. This is called calibration and
is
done automatically by your compass. However, if you
would like to manually calibrate the compass, the
following instructions will show you how.
Sometimes, strong magnetic fields can affect the
compass. If the compass display does not show a
direction, and CALIBRATE COMPASS is displayed on
the DIC, try calibrating the compass as follows:
1. Drive the vehicle to an open, flat area.
2. Press MODE to display COMPASS CALIBRATION.
3. Press SELECT to display PRESS RESET TO
RECALIBRATE and then press the RESET
button.
4. The display will change to SLOWLY DRIVE IN
SMALL CIRCLES. Drive the vehicle in small
circles. Don't drive faster than 10 mph (1 6 km/h).
5. Continue to drive in circles until the CALIBRATION
COMPLETE message is displayed on the DIC and
a direction is shown for the compass.
Compass Accuracy
Your compass may show different headings around
bridges, power lines, large metal objects and steep hills.
This is normal and is true of compasses in general.
If you put large metal objects like golf clubs in the trunk
they could affect accuracy. If the affect is minimal,
the compass will adapt to these objects over time.
If you use an antenna with a magnetic base, it is best to
mount it away from the center of the trunk near the
rear window.
The rear defog system can affect accuracy, and the
compass corrects for the rear defog. However, if the rear
defog is turned on while making sharp turns, the
accuracy may be off. When you turn the rear defog off
again, the accuracy returns to normal.
Be aware that metal objects are sometimes buried in
the ground. They can affect accuracy and you may not
know they are there. As an example, many concrete
roads have metal reinforcements inside.
Also, if you drive with the trunk open, this could affect
accuracy and could decalibrate the compass.
Your compass should be calibrated. You will know this
when a direction is shown and the CALIBRATE
COMPASS message is no longer displayed.
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