I installed an Haltech Elite 2500 on my '95 with a custom wiring harness. I connected 1M (the green and red wire), the speed sensor wire to my SPI1 input (Haltech's input for the drivetrain speed) and strangely the ECU only reads the speed when the cruise control is in the ready position.

Perhaps I have pinned the wrong wire from the body harness? I have attached a picture. How do I get it to read the drivetrain speed all the time without the cruise control button depressed?

 

Go check the Haltech section - just posted a possible answer to your post there. Summary - your speed sensor wiring is likely missing a ground return to the Haltech's sensor ground, and that path is likely being provided by your cruise switch.