Link doesn't work. Clive but I've found a circuit diagram for the freelander to compare with the original.Do you have a PDF reader?
http://www.google.co.uk/url?sa=t&rct=j&q=freelander%201%20wiper%20circuit%20diagram&source=web&cd=2&cad=rja&ved=0CDgQFjAB&url=http%3A%2F%2Fmacassemble.com%2Flrm%2Ffreelander%2FFreelander%2520Electrical%2520Circuits%2520(2002).pdf&ei=V9M_UPevM-f80QXa84GABQ&usg=AFQjCNHEwIgfGH6V1U18Wp7CnjQm9E7dMw
The black looks like an earth.
Finally, as an example of World Class Pedantry: DC circuits are actually positive and negative, whilst live and neutral are AC notations. So, in a car, you would not have a live feed but a positive one. I am also braced for arguments regarding conventional versus actual DC current flow! Bring it on. I need to get out more....
And Bongo: we still use Avo meters: I still have one in its leather case!