I have a 2004 GTP motor swapped into my 87' GT. I just converted my transmission to a 1990 FWD Getrag from a Beretta 3.1. I used Rodney's Slave adapter, and his linkages, both worked great.
When swapping the transmission from the Beretta from 1990, its my understanding that the VSS is a digital hall effect 24,000 ppm VSS. I bought the dakota digital SGI-5 C converter and supplied it power, and ground. The green light came on. I cut the VSS connector and put the Yellow on INPUT and the Purple on SENSOR GROUND. I placed the speedometer supply in the OUT 3 pin, which is labeled 4000ppm output. I have the switches on the unit set to OFF OFF ON OFF.
The speedo will not go above 10mph. If placed into the OUT 1 pin, it reads about 80mph at 15mph.
When speedo is attached to OUT 2, it does nothing.
I got it to work! They had directions for what sounded to be my exact situation, but I had to do application #3 (regarding replacing a GM transmission with a newer one), but in addition I had to turn all 4 switches to off, and change the output to output #3. Just for future trouble shooters I am having some electrical interference though. The directions said to twist the wires together to reduce that, so I'll try that.
wouldn't your ECM have a 4000ppm output which you'd only have to create a simple digital to analog conversion circuit for?
I originally misunderstood the post, and thought that the VSS was not talking to the PCM correctly. I'm guessing that's NOT the case. But yeah, your PCM ought to have a speedometer output that will just need to be filtered.
The ECM/PCM should have the VSS going into it. There should be a 4000PPM signal coming out but it's "digital" and needs to be made analog to work with the Fiero VSS wire in the C203 connector which goes to your speedo.
That the problem, I just swapped in a 1990 Beretta transmission with a different magnetic VSS. It doesn't output 4000 ppm, it puts out something like 24,000. My PCM was programmed to work with the speedo before, I never made a small circuit to make it work, Fieroflyer just made it work.
The best way to wire up your VSS is straight to the ECM. The 24,000 signal from the beretta transmission is what your ECM in stock configuration is expecting to see. The 4T65-HD's put out 24,000 PPM. There is a wire coming from the ECM that is an ouput that runs the GTP's Speedometer. The signal is a grounded pulse, So it needs a simple pull-up circuit in order to send the correct signal to a Fiero speedometer.
You could use a Dakota digital unit, but it is not needed in your application. But... if you insist on using it, All switches off. Out 3. - to the yellow wire of the speedometer (on C203), and on the ECM VSS Yellow wire. Ground your purple C203 Speedometer wire, AND the ECM's VSS purple wire. Wire both your VSS directly to the SGI-5 via the Input and sensor ground wires. Set your calibration to 4 Corse, 16 Fine. Should get you close to where you want to be.
Your ECM gets the VSS for the transmission instead of going straight to the SPEEDO like a Fiero normally does...
Your ECM takes the 24000 (or whatever because it's reprogrammable) and outputs 4000PPM digital for a speedo. You need to have the ECM set to use a divisor of 6 for the 4000PPM output.
You use the digital to analog circuit described several times here to convert that signal into what your Fiero SPEEDO is expecting (analog)...
Nothing is sent back from your speedo to the ECM like a Fiero normally does...
[This message has been edited by lou_dias (edited 04-01-2014).]
The best way to wire up your VSS is straight to the ECM. The 24,000 signal from the beretta transmission is what your ECM in stock configuration is expecting to see. The 4T65-HD's put out 24,000 PPM. There is a wire coming from the ECM that is an ouput that runs the GTP's Speedometer. The signal is a grounded pulse, So it needs a simple pull-up circuit in order to send the correct signal to a Fiero speedometer.
You could use a Dakota digital unit, but it is not needed in your application. But... if you insist on using it, All switches off. Out 3. - to the yellow wire of the speedometer (on C203), and on the ECM VSS Yellow wire. Ground your purple C203 Speedometer wire, AND the ECM's VSS purple wire. Wire both your VSS directly to the SGI-5 via the Input and sensor ground wires. Set your calibration to 4 Corse, 16 Fine. Should get you close to where you want to be.
Great thanks. I don't want to use the SGI-5 if i don't have to. This is exactly the answer I was looking for +
I am having some electrical interference though. The directions said to twist the wires together to reduce that, so I'll try that. 
