Patrick Sweeney

It will go crazy when the ignition is turned on.  So when power is put to the speedometer.

It will go crazy when its plugged in.  Brand new Speedo.

I have the dip swithes set.  But they only control the accuracy of the speedometer is what I'm told.  

I have a 1989 R688ST.  I recently replaced the transmission from a 9 speed Fuller to a 13 speed Fuller.  The original speedometer was cable to the rear of the transmission.  The new 13 speed is sensor on the yoke.  The new electronic speedometer is five wires: power, ground, dash lamp, and 2 sensor wires.  I have good ground and power and I get the display for the speedo.  I also replaced the sensor on the yoke.  Everything is new.  The problem I am having is that when the speedometer is plugged in, it will go crazy, to 45MPH, then to 85, the back to 25 etc.  Any help would be great.  I can't figure out what I'm doing wrong.  I believe I have everything connected correctly.