240sx tach problems

[TupperWare]

I have a 1990 240sx with a stock ka24e, and standard cluster. My tach doesn't work at all, I'll start the car, the it will bounce up. But I think it's just the vibration from the car making it do that. So when I start, it bounces then goes back down. After a little time I installed power steering and something happened and then the tach started to bounce like crazy, like it kinda wanted to work. Then after a day it went back to normal staying as 0 rpm. Then I was driving around and something happened and it started to bounce like it wanted to work but then stopped. I assume it's some wires, I know the wires from the ECU to the cluster, but can't find where the ECU gets the signal from the engine. Can anyone help me with this? and explain where the ECU gets the signal from?

[kashira kureijii]

Check grounding, and if car is well grounded, then check the speed sensor on the tranny

If car is not well grounded then the tach will bounce
If a tooth or some shit is busted in the speed sensor ( or if the wire is cut , or if the cluster shorted out) than shit will be messed up

This should go in the small questions thread by the way

[TupperWare]

Thanks, I'll check check everything later when we have our lift installed. And the Reverse sensor in the tranny was broken too so I wouldn't be surprised if another sensor is broken. And I keep that in mind where to put this in the forums. If anyone else has an idea, all the help will be appreciated.