Trans to speedo wiring question

[resto-mod]

I've got a Autometer type electronic speedo and a 4L60 from a '94 vette. I ran the wire from the speedo into the wire coming from the ECU, but it's not calibrating correctly. I've tried to calibrate it several times, but it seems that it won't read over 40mph. It seems as though the pulse "tops out" at whatever 40mph is on the speedo. Is there a wire coming from the trans that I could (should) be tapping into instead of the one out of the ECU? Thanks for help on this.

[86Cutlass383SR]

I called Autometer about wiring my electric Sport Comp speedo. I'm running an 89 based ECM and TPI style injection. Your setup "MAY" be differant than mine but I'll share what they told me about mine.

I ask if I could go from the electric speed sensor located on my trans to the speedo and then on to the ecm. For some reason, (I'm no wiring expert) they told me to run the wires from the trans sensor to the speedo and another wire from the sensor to the ecm.

I don't have my setup up and running yet but I am getting ready to do the wiring install. I'm not sure why you can't run from the trans sensor to speedo and then to the ecm. I think that's even the way the instructions show but the tech I talked to on the phone said not to. :hmm: :dunno: