The compass is capable of distinguishing eight primary directions:

The calibration procedures that are described in this section establish a base direction for the compass to work from. Once the compass is properly calibrated, the electronic display indicates the direction that the vehicle is facing. Under normal circumstances, no further attention to the compass should be required for a period of 2 years. Calibration may be necessary under the following conditions:

The compass is self-calibrating. This eliminates the need to manually set the compass. For a short time when the vehicle is new, the compass may appear to operate erratically and the CAL symbol or the letter C will display. Correct this by driving the vehicle in a complete circle 3 consecutive times. The symbol will turn off and the compass will function normally. If the compass displays a C at all times, the compass needs to be calibrated.

The compass module is shipped to the assembly plant in the fast calibration mode. In this mode, a C shows in the portion of the display that typically shows the compass heading. When is vehicle is calibrated outside the assembly plant, drive the vehicle in an area that is free from metal objects. Reset the compass by cycling the ignition (Off and ON). Drive the vehicle in a circle, oval or square until the C is replaced by the display heading.

If the compass is displaying a heading, then the compass is in the slow calibration mode. In this mode, the compass automatically calibrates for changes in the vehicle magnetism over the life of the vehicle. This autocalibration assures that the compass heading is always accurate and does not require manual calibration.

Excessive magnetism in or near the vehicle may cause the compass display to go blank. In order to distinguish between vehicle magnetics and surrounding magnetics, drive the vehicle to an area that is free from large metal objects. Rest the compass by cycling the ignition (OFF and ON). If the compass display goes blank within 20 seconds after the reset of power, then the vehicle magnetism is too high and the vehicle should be degaussed.

Important: Remove the Driver Information Center (DIC) before you degauss the vehicle.

If you install a new compass, use the following procedure in order to calibrate the compass:

1. Turn the ignition switch to the RUN position.
2. Depress and hold both the US/MET and the ON/OFF or the MODE buttons for approximately 10 seconds, or until the display reads CAL or C.
3. Drive the vehicle in a complete circle 3 consecutive times. The symbol turns off when the compass is calibrated. The compass will then function normally.

Variance is the difference between magnetic North and geographic North. In some areas of the world, the difference between magnetic and geographic North is great enough to cause false readings.

Use the following procedure in order to set the variance for the vehicle's particular locations. On vehicles with a MODE switch, the display must be in the COMP/TEMP mode before setting the variance.

1. Determine the location on the zone map.
2. Note the zone number.
3. Press and hold both the US/MET and the ON/OFF or the MODE switches.

The display will turn off.

4. After approximately 5 seconds, the variance setting appears on the display (w/o trip computer).

With the trip computer, only a number is revealed at the present zone.

When the variance setting appears, release both of the buttons.

5. Press the ON/OFF or the MODE switch in order to enter the geographical zone number.

The compass is now adjusted for variance.

6. Press the MODE button (w/ trip computer) or the ON/OFF button (w/o trip computer) in order to return to the main screen. This action will save the setting.

Due to the nature of the magnetic detection devices in the module, the compass may occasionally show false directions even when operating properly. Since the circumstances that give rise to these false readings may vary, some general knowledge of how the compass works is helpful in determining why false readings occur. Such perceived malfunctions may be the result of special circumstances, or a true system malfunction. Regardless of the problem, the first step in diagnosing the compass system is recalibration. If the problem persists after recalibration, review the following information regarding compass system functions for help in determining if the system is operating properly.

Recalibration of the compass may be necessary if the vehicle is operated a long distance away from the point of the initial compass calibration. There are many reasons for this, including the following:

When these circumstances arise, a malfunction may be suspected when, in fact, the system is operating normally.

An approximate 15 degree deviation (declination) from true NORTH occurs between the east and west coasts. This declination is the result of the earth's curvature. Various other deviations throughout the country are the result of differences in the magnetic fields.

The compass system may require recalibration if the vehicle's structure is altered sufficiently. This occurs because any significant alterations in the vehicle's structure will cause corresponding alterations in the vehicle's inherent magnetic field. Thus, when the vehicle's structure is altered, as in a collision, the compass readings may reflect the offset in the vehicle's magnetic field. The vehicle operator may then discover differences in compass readings from those previously observed along familiar routes.

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:

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:

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.

When travelling on winding roads, the compass readings may oscillate between 2 neighboring directions, such as NORTH and NORTHWEST. This occurs when the road coordinates coincidentally border the coordinates used by the system for the 2 different directions.