Somewhere on here a few years back, I read that once you remove the ECM, this buffer box is no longer grounded and therefore does not work, but I can't find the thread anywhere now. Could someone link me to that? Or... tell me what I need to do to reground the buffer box? I'm going to be installing digital electronics and since my car had cruise control, according to the manufacturer of the electronics, the speed signal can be sourced from this little yellow box on the back of my instrument cluster which is still in my car even though the cruise control unit and ECM was removed a long time ago. I will be pulling the entire cluster out to tap into it and was hoping I can reground the box there or somewhere else? Thanks for any help!

 

This might be it.

https://www.thirdgen.org/forums/engi...-function.html

Although I'm surprised you have a buffer box... I don't think my 84 does, even though it has cruise. If I remember right, the speedo cable cable plugs directly into the back of the cluster. I remember it being a PITA to get the clip off.

 

That's the one!! Thank you for finding that!