Hello,

My Trans Amīs electrical speedometer is not working. I have to drive without speedo because when VSS wires are connected then speedo needle jumps quikly to 120 mph even at idle speeds. And of course then car stops. I think ECU is programmed that way when certain speed is reached then engine misfires to limit speed.
Where or what is the problem?

 

sounds like your VSS is bad.

 

How can I be sure about that? Is there any way to control VSS parameters. I measured resistance (I know itīs not allowed with Hall sensor, but it didnīt worked so I tried anyway). Resistance was 1,6 kOhm (or near that). When I moved metal near sensor then resistance changed.

 

I'm not entirely sure, I believe you need an osciloscope. Another option is to buy a new one from an autoparts store and change it and if it works again then you fixed it, and if it doesn't change you can just take it back. From what I've read the only cars that had a vss buffer were 85-89 TBI cars, so don't have to worry if that went out.