Compass Diagnostics
If at any time the compass continually displays the incorrect direction, the reading is erratic or locked, verify the correct zone variance per COMPASS ZONE VARIANCE and manually recalibrate per MANUAL CALIBRATION. The electronic compass, although highly protected from changes in magnetic field, can be susceptible to large changes in magnetic field. Examples include, but not limited to: high tension power lines, large steel buildings, automatic car washes, large quantities of scrap metal, etc. While occurrence of this phenomenon is infrequent, it is possible.