I searched and found a lot of people asking about the swap, but not exactly with 3.4 swap. Vehicle is up and running, but the speedo doesnt work. It was originally a mechanical speedo and I swapped in an electronic one, ran all the VSS wires to ECU, etc. I ran a wire from the terminal in the back of the speedo (since my body harness didnt have this being mechanical) to the SPD on the 98 ECU. Still didnt work. Any one know what I am missing?

 

i think you need a signal from the vehicle speed sensor as well on your tailshaft of your tranny there is a plug with three wires one positive, one ground, and a signal wire which is the one your looking for

 

That makes sense. I was thinking the VSS was the INPUT to the ECU and the SPD terminal was the output to the speedometer, so I thought by splicing into that one it would get its signal. I will try to splice into the VSS signal and see if that helps, thanks!

 

I tried wiring it into the signal wire from the vss and still didnt get anything. I guess its possible the speedo i got from a junkyard is no good. It should work this way and its not. Between this and my a/c line being too short its more of a PITA than the whole swap was!

 

tell me about it... I chased a bad cluster for two days trying to wire the speed sensor correctly come to find out the speedo in the dash was bad

 

Put like couple of 1.5V batteries to it and see if it jumps. Those things are just glorified vote meters.... I kept the mechanical one and fed the ECU with the output signal from the cluster. My OBDII scanner shows the speed of the vehicle.