1996 GMC Sonoma Owner's Manual - Page 100

Speedometer and Odom-eter I Tachometer (Option) The tachometer displays the engine speed in revolutions per minute (rpm). Each tachometer has a different limit depending on the powertrain in your vehicle. The tachometer has three areas: normal operating range, red warning range and red danger range. Normal operating range shows your engine speed during normal driving conditions. For example; when the needle points to 2, it means the engine is running at 2,000 revolutions per minute (rpm). The tachometer needle will vary all the time that the engine isrunning. The red warning range tells you that your engine speed is reaching its upper limits. Don't drive very long with the tachometer in the red warning range. If you have a manual transmission, shift to a higher gear as soon as possible. If you have an automatic transmission, lift your foot off of the accelerator pedal. Your speedometer lets you see your speed in both mi,les per hour (mph) and kilometers per hour (lun/h). Your odometer shows how far your vehicle has been driven, in eithermiles (used in the United States) or kilometers (used in Canada). Your odometer is tamper resistant. It will show silver lines between the numbers if someone tries to turn it back. You may wonder what happens if your vehicle needs a new odometer installed. If the new one can be set to the mileage total of the old odometer, then it must be. But if it can't, then it's set at zero, and a label must be put on the driver's door to show the old mileage reading when the new odometer was installed. Trip Odometer rhe trip odometer can tell you how far your vehicle has been driven since you last set the odometer to zero. trip I'o set the trip odometer to zero, press the button near the readout. NOTICE: Do not operate the engine with the tachometer in the red range, or engine damage will occur.