Compass Calibration Procedure Service

Compass Calibration
The compass must be calibrated to guarantee proper operation. Calibration should take place on a level surface in an area free of large metal objects, such as other vehicles, large buildings, bridges, underground cables, railroad tracks, etc.

If the "CAL" indicator is lit, the compass should be calibrated. The vehicle will be shipped with the "CAL" light on. Under certain conditions the "CAL" light may also come on during driving. Also, during normal driving, the compass may appear inaccurate, and the "CAL" indicator may or may not come on. In either condition, calibration is required.

Compass Calibration:

To calibrate the compass, drive in complete circles at a speed of 7-10 mph, until the "CAL" indicator is off (2-6 turns). If the "CAL" indicator is not on, prior to calibrating the compass, the "CAL" light will come on for a few seconds to indicate it has been calibrated. When the "CAL" indicator goes off, the compass is calibrated and should display correct headings (for all conditions). Verify proper calibration by checking North (N), South (S), East (E), and West (W). If the compass does not appear accurate, repeat the calibration procedure in another area.

NOTE: Drive in a small circle (try to keep steering wheel in a fixed position) between 7-10 mph, until the "CAL" light goes off.

Variance Setting Procedure

Variance Settings:

Variance is the difference between magnetic North and geographic North. To adjust the compass variance set the CMTC to Compass/Temperature mode and press both US/M and STEP buttons for up to one second. The symbol VAR and current variance zone number will be displayed. Press the STEP button until the variance setting for your location is displayed. After five seconds of inactivity, the displayed zone will be automatically set and normal operation resumed in the Compass/Temperature mode.

A forced calibration takes place by driving in a circle between 5 and 11 MPH (8 and 18 Km/h). The diameter of the circle should be between 30 and 100 feet (9 and 30 meters). The speed should vary by no more than 3 MPH (5 Km/h). Otherwise the calibration will be aborted. The calibration should take place on a level surface free of any magnetic disturbances (such as buildings, underground cables, nearby bridges, railroad tracks and so forth). When the CMTC has automatically sensed that a forced calibration is taking place, the "CAL" indicator will light on the display and then turn off after the CMTC has determined that a successful forced calibration has taken place. After this forced calibration takes place, normal driving will enable the auto-calibrating feature to refine the forced calibration and also to maintain the current calibration. If the "CAL" indicator does not turn on, then retry the calibration procedure in another area.

To ensure that the compass has been properly calibrated, point the vehicle in each of the following four directions: (N), (S), (E), and (W). The "CAL" light will be ON, indicating that the module is new and will need calibrating.

Direct Method
Turn the vehicle to head in either a North or South direction. The vehicle must be within 45 degrees of the North or South position or the SETTING the VARIANCE will be ignored. The vehicle may be stationary or driving at any speed for this operation. Depress the STEP button until the Compass/Temperature screen is displayed. Simultaneously press both the US/M and STEP buttons up to one second, than the symbol VAR and the current variance zone number will be displayed. Within the next five seconds momentarily press the US/M button. The variance will be set and normal operation in the Compass/Temperature mode resumed. If the US/M button is not pressed within the five seconds interval, the compass variance shall not be changed and normal operation in the Compass/Temperature mode resumed. If the VAR symbol flashes twice before resuming operation, the new zone was not accepted. Realign the vehicle to within 45 degrees of North or South and try again.