Inside Rearview Mirror Description and Operation: Compass
WARNING: This page is about a different car, the 2002 GMC Savana Special, 2002 GMC Savana Camper Special, 2002 GMC Savana, and 2002 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.
The electronic compass includes a magnetic field sensor and a microprocessor. The microprocessor receives inputs from the sensor, processes these inputs, and provides a heading on the compass/temperature display.