Defrost light wiring, Where does the brown wire go to? Options

[euro914er]

Hi everyone,

Into year 3 of my 914 ownership (1974 1.8, Saturn Yellow) and still only been around the block twice following a top engine rebuild. But that's a long and different story....

Trying to iron out a few electrical oddities, one being the defrost light wiring. I have two wires coming from it; a blue and black for the bulb that disappears into the tunnel and a shortish light brown wire with a ring terminal on it. I'm assuming this ground - but I can't see anywhere obvious within reach of the available cable length. Curiously when I touch this wire onto the defrost lever arm whilt it's in the up position, the blower starts and the light comes on. Great - but I assume this is not where it is acutually supposed to connect to?

Any pointers gratefully received.

David