degens

I have a 1996 2.8V6 which I understand has the Ford EEC IV Engine Management Unit. Having read a lot of information from the web it would appear I can read the fault codes from this by connecting to a 3 Pin plug. Does anyone have an idea where this is as I can't seem to find it. I have found a large plug under the ashtray in the central console but I don't know if this is related or what pins to use. Any help with this would be greatly appreciated. Thanks Phil.