Dodge 2009 Ram Diesel Owner's Manual Supplement page 22

20 UNDERSTANDING THE FEATURES OF YOUR VEHICLE
1. Turn the ignition switch to the ON/RUN position.
2. Press the MENU button until "Personal Settings" is
displayed.
3. Press the STEP button until "Compass Variance" is
displayed.
4. Press and release RESET button until the proper
variance zone is selected according to the map.
5. Press and release the Compass button to exit.