GM Service Manual Online
For 1990-2009 cars only

The trip odometer is located on the instrument panel and shows how far the vehicle has been driven since the trip odometer was last reset. To reset the trip odometer to zero, press and hold the trip/reset button on the speedometer for about two seconds. The DIC buttons can also be used to reset the trip odometer.

Press the trip/reset button to switch between the trip odometer and odometer or use the DIC buttons.