I am not sure if I will find my answer here or not but I will try.
I got my 4L60E put in and my TCI controller wired up. It looks like it is all working good, but for some reason I am not getting a vehicle speed reported into the ECM. I did some datalogging and I don't see any speed recorded. My speedometer is working properly. The TCI controller has one orange wire coming out for speed. I hooked this to the yellow wire (VSS input) going into the ecm and grounded the other wire (VSS sensor ground). Should the other VSS wire (ground) be hooked up to the speed output from the controller as well?

 

The TCI box doesn't have a speed output (which would be a mouth, like, it doesn't tell the world how fast the box is going); it has a speed input (more like an ear, the box listens to the VSS telling it how fast the car is going).

Likewise, the VSS doesn't have an input (like something somewhere tells it how fast the car is going); it has an output, on which it generates pulses to tell the rest of the world how fast the car is going.

Not that it matters a whole lot; but if you get the terminology right, the concept of how it works and therefore what might keep it from working, might become clearer.

No you should not hook the VSS's ground lead to the VSS input wire of the TCI box. It sounds to me like you have the TCI box hooked up correctly, as far as that goes.

The VSS output however is a fairly low voltage. The signal may be at too low of a level to drive the TCI box directly... kind of like hooking a microphone directly up to a speaker... you won't hear much out of the speaker. You probably need a "buffer" amplifier between that and the TCI box.

 

I don't think you realize that the TCI unit has both an input it recieves from the VSS and the unit also generates an output used for the speedometer and ECM. I know how the VSS works and the signal it is putting out is enough for the TCI controller to use. The second half of the equation is coming from the TCI controller. It all comes from one wire. I have this wire splced into my harness that used to be connected to the VSS, more specifically the yellow wire, vss input. My speedo is working correctly, but my ECM is not seeing the vehicle speed. As far as I understand it they both (speedo & ECM) use this yellow wire to get vehicle speed and the other wire is simply a sensor ground.

 

Just taking a stab at it.
Check what pin you are using on the 730 for the input.
In $8D there is a selection bit for optical or magnetic type.
They use different pins depending on which type you use.
I do not know if the other mask has the switch or not.

As far as the signal ground goes, I always try to run the "common" of a signal back to the point of origin of the signal. Keeps the sender and receiver at the same ground potential.
In any case, the grounds will eventually lead to chassis in a vehicle. Some resistance between them can cause offsets. That's why its best to keep them going the same location.

So the speedo on the dash driven directly from the Dakota box and "tee'd" into the wire feeding the ECM?
Sounds like the signal is incorrect for the pin you have it connected to.
HTH

 

I am not using a Dakota box. I just cut the VSS plug off at the trans and ran the speed output from the TCI TCU directly to the yellow, vss signal and then grounded the other VSS wire to the chassis.