Operation In Urban Areas

The electronic compass, like any compass, is influenced by external magnetic fields. Filters that are programmed into the compass function to counteract much of this external magnetic interference. These filters vary with the vehicle speed. They function by relating the vehicle speed to the time in which the vehicle could conceivably change directions. The filters correspond to the following speeds:
^ 0-16 km/h (0-10 mph)
^ 16-64 km/h (10-40 mph)
^ Above 64 km/h (40 mph)

The filters function by taking into account that vehicle directional changes ordinarily do not occur as quickly at higher speeds as at lower speeds. The filters help avoid false readings caused by large steel structures, such as the following objects:
^ Skyscrapers
^ Bridges
^ Roads with steel reinforcement
^ Railroad tracks

Sometimes, the field projected by these structures leads to a reading that represents too drastic a change of direction for the prevailing driving conditions. When this happens, the filters intervene in order to prevent changes in the directional display. However, under borderline conditions, as in large cities with slow driving, the compass may give false readings and appear to be malfunctioning. If this occurs, test the compass in an open area, free from magnetic disturbances.