2001 Tahoe tacometer not working

Did you check the sending sensor? If you changed the tack and it still does not work, it may not be the tack. Wires connected and good? I think the sensor picks up a signal from the cam and that may have come off or lost it's juice. Have the sensor checked. I really wonder why we need tachometers anyway if we are not racing? With automatic transmissions doing all the work now, or get use to the speedometer when using a manual transmission, a tack is just another space filler on the dash. I use one in my older Corvette to keep from over revving the motor or lugging it when in heavy traffic and slow down, other that that, I just use my rear view mirror looking for red lights.