Tachometer issues - instrument cluster

[tycksena]

I recently bought my truck ('02 GMC Sierra 2500HD) and the tachometer was jumping around between 0 and where it should be at. I read up here on the forum and figured it was a stepper motor issue as these are pretty common. I went on Ebay and bought a stepper motor for my instrument cluster and installed it and now have no response from the tachometer with either the new or the old stepper motor.

Has anyone had success switching out the stepper motors on early NBS trucks? I was wondering if I bought the wrong stepper motor? or if there is some bigger underlying problem? I'm sure the instrument cluster gets the RPMS from somewhere on the engine, could that be the issue?

Your help is much appreciated.