I understand it is not so simple with AU's and BA's and the simple circuits used to test preceding models will not work. Silicon Chip, the electronics magazine, ran an article some year ago about the OBD II plug that Jaycar has available and pointed out that the Falcon's were not OBD II compliant so even though they used an OBD II plug the circuits they suggested could not be used to read their codes. Similarly even US sourced code readers (I understand US Fords comply with the OBD standard) may not work for Australian Fords. Nonetheless there may be enough info in the genuine Ford workshop manuals to design a suitable circuit to build your own. The cheapest commercial approach may be to buy a code reader that works with a laptop computer.
My engine is EEC-IV and I have been using this simple US code reader for a few years (cost $35 then) and it's worth its weight in gold. Quick plug in, turn the ignition on and it does its stuff and you count the code beeps/flashes etc. Also reads engine running codes etc.
There were costlier display code models available with causes etc but I've never had any code issues in 12 years so I figured a simple quick unit would suffice.
But as far as OB11 stuff goes what Aussiblue mentions maybe so, but you could reserach the OB11 readers that display in the top right corner of this link.