so all of my gauges work except the speedometer and tach which sucks cuz those are the ones i need to drive. the speedometer works, but it only starts moving once you get to about 40 so when your going about 75 it says your going 30.

the tach used to work about half the time but now it doesn't work at all. when it did work, there was a ticking noise coming from it.

what could be causing these problems and how do i fix it?

 

I just acquired a 91 rs. I have a similar problem, speedo only works when at interstate speeds after a few miles of driving, and my tach stays pegged out except when the starter is engaged. It moves to about 4 or 5k but then goes back to maxed out.

Any help would be much appreciated.