2011 GMC Savana 3500 Cargo Owner's Manual - Page 121

Instruments and Controls Compass variance is the difference between the earth's magnetic north and true geographic north. If the compass is not set to the zone where you live, the compass may give false readings. The compass must be set to the variance zone in which the vehicle is traveling. To adjust for compass variance, use the following procedure: Compass Variance (Zone) Procedure 1. Do not set the compass zone when the vehicle is moving. Only set it when the vehicle is in P (Park). Press T until PRESS V TO CHANGE COMPASS ZONE displays. 5-5 4. Press 3 until the vehicle heading, for example, N for North, is displayed in the DIC. 5. If calibration is necessary, calibrate the compass. See "Compass Calibration Procedure" following. Compass Calibration The compass can be manually calibrated. Only calibrate the compass in a magnetically clean and safe location, such as an open parking lot, where driving the vehicle in circles is not a danger. It is suggested to calibrate away from tall buildings, utility wires, manhole covers, or other industrial structures, if possible. If CAL should ever appear in the DIC display, the compass should be calibrated. 2. Find the vehicle's current location and variance zone number on the map. Zones 1 through 15 are available. 3. Press V to scroll through and select the appropriate variance zone.