Very small circuit board attached to tachometer
 

A while ago, I removed my speedometer and sent it away for repair. Now I'm reinstalling it in the instrument cluster. While reinstalling it, I found a very small circuit board connected by two wires to the tachometer. The circuit board has two resistors and a transistor on it as shown in this picture:

http://forums.pelicanparts.com/uploa...1726027203.jpg

On the back of the circuit board is a ring of exposed copper as shown in this picture:

http://forums.pelicanparts.com/uploa...1726027203.jpg

Seeing the copper with a hole in the middle made me think maybe the circuit board is supposed to be attached to something with a screw, but I don't remember detaching it. Is it supposed to be attached to something? If so, what?

that should attach to the back of the speedometer, with the black plug at the tach.
it is the vehicle speed signal that goes into the calculations behind the upshift light.