Ok so I have been trouble shooting my tach for some time now the reason I have yet to replace is it b/c I have seen it on many occasions work. Ok so here are the weird things I have noticed about my tach :
1) TACH WORKS !!!!! But only on hot days ? . Ya thats right whenever at night I want to go somewhere when its cool the tach doesnt work but if the car sits in the sun persay when im in class when I come out it reads as far as to redline ? Im confused.
2) I hooked up my HKS TYPE 1 Turbo Timer and taped everything to act as a aftermarket tach and it works perfectly reads all the way to red-line digitly.
3) Trouble shooted bad wire through dash? No that either getting a good signal.

My dad proposed the idea that the spindle might be to tight and that when it gets hot it loosens the plastic so that the needle can rev freely. Anyways I have no idea what can be wrong but in following my dads Idea I got some 3-1 oil to lub the spindle. Anyone got any ideas ?

 

Thats a common problem, it has something to do with the soldered connections on the back. Mine works only when it wants to. take the dash off and be sure all the connectors are plugged in.
The tach may need to be replaced.
-Ben

 

It's just broken solder joints on the board for the tach. If you can solder, it's a super easy fix. If you can't solder, find a 2nd gen guy - we can fix broken solder joints in our sleep .

Dale

 

OK I did solder the joints on the back but still no go ? Any ideas ?