GT4 wiring diagram question

Some butcher has been into my car and re-routed the headlight wiring to bypass the broken stalk switches. Verell has rebuilt the switches and now I'm trying to replace the factory wiring which for the most part has been cut out.

Coming out of the column stalk switches there is a heavy red wire, a heavy yellow wire, a heavy black wire and a lightweight green wire.

Yellow wire I have been able to trace and re-connect
Black wire I have also been able to re-connect.
Small green appears to trigger a relay at the main board so should be able to sort that one.
Red one, trouble! Wiring diagram shows the red going to a unit marked as Number 21. BUT..........weirdly Number 21 in the legend for the wiring diagram has nothing written against it to tell you what 21 actually is.

Of all the numbers, only 21 has no description. Has anybody else struck this or have any idea what number 21 on the wiring diagram is?

 

Thanks Steve, been a while. Working on Testarossa seems easier than these old 308's.

 

That may be n optional thing Steve. I've seen some GT4's with a separate control for intermittent wipers below the standard three switches and indicator lights on the right side of the instrument panel. But my early car doesnt have this so still wondering what this heavy gauge red wire could be for.