My apologies folks......
I seem to have 'jumped the gun' a little with my earlier message. I've gone through the wiring diagrams (thanks Jeffrey) and more or less answered my own questions. In relation to the connectors at the voice synthesiser - the answer is 'no', they should not be connected together.
The other question was in relation to an unidentified brown with red stripe wire at the radio. The diagrams show this goes to pin 16 on the voice synthesiser, but I still need to know what it should be connected to at the radio end.
'86 80 Sport