2005 Pontiac Montana SV6 Owner's Manual - Page 201

Retro-Active Reset Each of the two trip odometers has a feature called retro-active reset. This feature can be used to set either or both trip odometer(s) to the number of miles (kilometers) driven since the ignition was last turned on. This can be used if you forget to reset your trip odometer at the beginning of a trip. To use the retro-active reset feature, press and hold the trip/reset button for at least three seconds. The trip odometer will then display the number of miles (kilometers) driven since the ignition was last turned on and you began driving. If you use the retro-active reset feature after you have started the vehicle, but before you begin moving, the display will show the number of miles (kilometers) you drove during the last ignition cycle. Once you begin driving, the trip odometer will accumulate mileage. For example, if you have driven 5.0 miles (8.0 km) since you started your vehicle, and then activate the retro-active reset feature, the display will show 5.0 miles (8.0 km). As you drive, the display will then increase to 5.1 miles (8.2 km), 5.2 miles (8.4 km), etc. Only the trip odometer that is displayed will be affected by the retro-active reset so that both trip odometers can be used separately. Tachometer The tachometer displays the engine speed in revolutions per minute (rpm). Notice: If you operate the engine with the tachometer in the shaded warning area, your vehicle could be damaged, and the damages would not be covered by your warranty. Do not operate the engine with the tachometer in the shaded warning area. 3-37