4th gen electric speedometer/VSS/ECM
 

How do the 4th gens accept the VSS signal off the trans to operate both the speedometer and ECM??

My stock 89 speedometer receives the cable from the 700R4 trans and also has a buffer that converts the spinning cable to an electric signal for the ECM.

My thought is to pick up a 93+ speedometer and run my VSS wires to that/to the ECM... however it works on the 4th gen cars. That way I can see what speed the output signal is sending and adjust my Dakota Box accordingly.

everything's electronic, no cables for it. If that's what you were asking.

On the 4th gen cars the VSS signal does not go directly to the speedometer. It is sent to the ECM. The Gauge is connected to the ECM which is where it gets the signal. The Signal from the VSS is a little different compared to the signal given from the ECM, I was told it is a little rough if the signal is taken directly from the VSS. The ECM is supposed to act as some type of buffer.

That's what I was looking for.

I'm still trying to square away my VSS since swapping to the T56. I have the Dakota Box to convert the T56 VSS signal to match my ECM but I need a speedometer in line so I can see what it is reading in order to adjust the Dakota box for the correct signal to the ECM.