Dodge 2009 Ram 3500 - Manual (Page 154)

NOTE: Magnetic materials should be kept away from
the overhead console. This is where the compass sensor is
located.
Compass Variance is the difference between magnetic
North and geographic North. In some areas of the
country, the difference between magnetic and geographic
North is great enough to cause the compass to give false
readings. If this occurs, the compass variance must be set
according to the Compass Variance Map.
NOTE: The default for the compass variance is Zone 8.
To set the variance: Turn the ignition ON and set the
display to “Compass/Temperature.” Press and hold the
RESET Button Compass Variance Map
152 UNDERSTANDING THE FEATURES OF YOUR VEHICLE