I have four final wires to hook up from my 3800 harness pictured below…



They come from the PCM and are:

White - pin 59 on clear connector
Light Green/White - pin 55 on blue connector
Dark Green - pin 72 on blue connector
Pink - pin 27 on clear connector

I am assuming they hook into the chassis harness running through the center console, can someone help me out here?

Only one that you might need is 55 Blue. That is your 4000 PPM output. You need it for sure if you are running the 4T65E/4T65E-HD. It is optional if you are running a MT.

So what is the pin 55 blue (4000ppm) get connected to ?

I'm running a getrag so I will just leave them be for now, thanks!

When running a MT the VSS output can be wired to both the PCM input and the speedo input (via C203). Nothing extra is needed and the wire on Blue pin 55 is not used.

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When running the 4T65E/4T65E-HD the transmission VSS puts out 24,000 PPM. The Fiero speedo is set up for a 4000 PPM sine wave input. So you can't just hook the two together. So with the AT, you connect the VSS output to the PCM VSS input. Pin 55 Blue is the 4000 PPM output of the PCM. But you can't just hook that to the speedo. The 4000 PPM output of the PCM is a square wave output. So you have to use a simple buffer circuit to convert that square wave output to an input the Fiero speedo will correctly work with.

I sell the speedo buffer circuit for $20 shipped here - http://www.reddevilriver.com/Related_Products.html

You can also build your own buffer circuit using the instructions here - http://www.gmtuners.com/fiero/speedo2.gif

[This message has been edited by phonedawgz (edited 11-17-2013).]