My tach just bounced right to 0 RPM today....even though I was doin 40MPH in 4th gear. Wonderful.

Later on, it decided to mess with my head.....it bounced like crazy back and forth between 0-over 9000 rpm...then it started working normally for about 3 minutes. Then, it stopped.

30 miles later, still nothing. I've searched a bit, only to find that everyone who ever had this problem just went ahead with an aftermarket tach. I don't want an aftermarket one. Only one person said they had it fixed, and said that it cost a boatload.

What controls this tach? Is it wired off the distributor like aftermarket ones are? Is it wired to the ECU? Any help is appreciated. Thanks....

Best bet to get it fixed is a new (to you anyway) dash cluster. See if you can find a used dash cluster out of a awrecked car with similar mileage and put that in.

My GF's NX2K is this way.
Tach wire from distributor goes to the ECU
Tach gets its signal through the ECU
If you have cruise i think it goes through the ASCD unit as well. (to shut the cruise off if the RPMs get to high)

All the people that i have seen have this problem have replaced the dash cluster and fixed the problem. It looks like from all my research that it is an internal problem to the tach itself in the dash.

Sorry to be the bearer of bad news but hey its the truth.
Rick