What are these green boxes called?

[wheels87k5]

And are they worth anything? I've got these sitting around and I don't need them. I know they are used to send the ECM a signal and they hook up to the speedometer.

 

[dyeager535]

Vss buffers. Worth something I suppose, not a ton, but anyone going that route needs the correct speedometer as well.

Also used for cruise control, so not just useful for folks going injection.

 

[wheels87k5]

Does the speedometer provide the pulse signal, while turning, through the little photo eye that's positioned on the back? I remember some of it, but it's been a while. When I moved to an electric speedometer I had to buy the speed sensor that mounted to the transfer case, and that provided the signal to the ECM.

 

[dyeager535]

Does the speedometer provide the pulse signal, while turning, through the little photo eye that's positioned on the back? I remember some of it, but it's been a while. When I moved to an electric speedometer I had to buy the speed sensor that mounted to the transfer case, and that provided the signal to the ECM.

Yep. I think if you look where the eye fits into the speedometer head, and spin the cable fitting of the speedometer, you'll see two(?) Metal tabs that rotate.

I went electric speedo too, so much better than cable.

 

[Blue85]

On carb trucks, this 2000ppm signal is used for the cruise control. For TBI, it's also used as VSS for the ECM. By '91 the T-case had an electronic sender and the speedo cable was gone.