2005 Hummer H2 Owner's Manual - Page 121

In order to calibrate, CAL must be displayed in the mirror compass windows. If CAL is not displayed, push the COMP button for about eight seconds or until CAL is displayed. The compass can be calibrated by driving the vehicle in circles at five mph (8 km/h) or less until a direction is displayed. To adjust for compass variance, do the following: Compass Variance Compass variance is the difference between earth's magnetic north and true geographic north. If not adjusted to account for compass variance, the compass could give false readings. The mirror is set in zone eight upon leaving the factory. It will be necessary to adjust the compass to compensate for compass variance if the vehicle is outside zone eight. Under certain circumstances, as during a long distance cross-country trip, it will be necessary to adjust for compass variance. 1. Find your current location and variance zone number on the zone map. 2. Press and hold the COMP button for five seconds until a zone number appears in the display. 3. Press the COMP button on the bottom of the mirror until the new zone number appears in the display. After you stop pressing the button, the display will show a compass direction within a few seconds. 2-45