Speedo and odometer don't work
 

Hi all, I have a 1986 Porsche 911 cabriolet and my speedometer and odometer recently stopped working. I already verified that the impulse sender (speed sensor) is operational. While checking grounds I came across a disconnected electrical connection under the hood on the drivers side. It has a brown wire and a black wire with white stripe. The connector has a green dot on it. See pic. I cannot find where this is supposed to plug in, if it should at all. Does anyone know what this plug is for and where it should plug in? Thank you.