Remote Central Locking help

[chris1975]

My dad just purchased a W Reg 2000, Ford Transit 350lwb High Roof,

However it has worn key and lock syndrom and so he has purchased 1 of these http://www.amazon.co.uk/Universal-Remot ... B002RLB87E , and we aint got a clue wether the current locking system is positive or negative.

Not only that not sure which wire is used to open / unlock and close / lock for to enable us to connect this up.

Any help appreciated

Regards
Chris