Chevrolet 1994 Astro Passenger Owner's Manual page 114

The digital odometer will read
ERROR
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
Standard Cluster
m
Digital Cluster
The trip odometer can tell you how far your vehicle has been driven since
you last set the trip odometer to zero.
To reset the trip odometer on the standard cluster, press the button near the
readout.
The trip odometer
on
the digital will appear in place of your regular
odometer when you press the TRIP button.
To reset the trip Odometer on the digital cluster, press the RESET button. To
change back to the regular odometer, press the TRIP button again.