[bestgenman]

It's been a long time since delving into this problem but I'm pretty sure the MPU enters the DDEC in the 30 pin connector.  It's worth a check to see if there is something wrong.  Check the wires going into the connector and the pins on the DDEC side.  

I've dug up the drawings of your DDEC -II 30 pin plug.  The first page of the pdf is the diagnostic connector inside.  You can check codes by watching the "check engine light" CEL while shorting pins A to M.  Use this for future diagnostics.

 Wires 556 & 557 are from the MPU to the DDEC (see page 2),   Page 3 shows the wire colors to be 556 BLUE LT/BLK & 557 BLUE LT/ORN and are in positions E2 & E3.  Page 4 shows the 30 pin ECM connector.  

Now do a continuity check of those wires from the 30 pin to the MPU (while unplugged) to be sure there is a path.  The MPU output is AC so polarity is not a factor. 

If you have a good MPU and the wires are continuous and the pins are not corroded or bent or pushed back in the 30 pin, the ECM should be getting a road speed signal.  You've changed everything else so it should work unless there is a wiring problem from the switches to the ECM.  But, you have a drawing now so hopefully it will be an easy fix.

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