GM Service Manual Online
For 1990-2009 cars only

The speedometer shows the vehicle speed in both miles per hour (mph) and kilometers per hour (km/h). The odometer shows how far the vehicle has been driven, in either miles (used in the United States) or kilometers (used in Canada).

Engine Hour Meter Display

The Driver Information Center (DIC) can also display the number of hours the engine has run. To display the engine hours, turn the ignition off, press and hold the reset button for at least four seconds. The hour meter displays for up to 30 seconds, or until the ignition is turned on. See DIC Operation and Displays for more information.