Cadillac Automobile Owner's Manual page 257

This system may not be available or
interferences may occur if any of the
following are true:
Signals are obstructed by tall
buildings, trees, large trucks,
or a tunnel.
Objects are located on the front
dash of the vehicle.
Satellites are being repaired or
improved.
After-market glass tinting has
been applied to the vehicle's
windshield.
For more information if the GPS is
not functioning properly, see
.
At times, the position of the vehicle
on the map may be inaccurate due
to one or more of the following
reasons:
Road system has changed.
Vehicle is driving on slippery
road surfaces such as in sand,
gravel, and/or snow.
Vehicle is traveling on winding
roads.
Vehicle is on a long
straight road.
Vehicle is approaching a tall
building or a large vehicle.
Surface streets run parallel to a
freeway.
Vehicle has just been transferred
by a vehicle carrier or a ferry.
Current position calibration is set
incorrectly.
and
Vehicle is traveling at high
speed.
Vehicle changes directions more
than once, or when the vehicle is
turning on a turn table in a
parking lot.
Vehicle is entering and/or exiting
a parking lot or a garage.
GPS signal is not received.
Roof carrier is installed on the
vehicle.
Vehicle is being driven with tire
chains.
Tires are replaced.
Tire pressure for the tires is
incorrect.
Tires are worn.
First time the map DVD is
inserted.
Battery is disconnected for
several days.