you have to try it like this:

1. hold down the odometer reset button
2. start the car while holding down the odometer reset button
3. hold the button until the word test appears
4. then continue to hit the button until the word "tach 1223" (those are just random # btw)

it will run until the car is turned off and restarted. there are some other interesting things in that menu too. ie fuel pressure, oil pressure, digital tachometer, and a bunch of other shit which i dont know what it means....but try it again and take a gander...