Trying to extract ECU error codes

[ShaneHobson]

I've searched the intertubes, read various forums, read the How To and still can't work out how to obtain error codes from my ECU.
When driving on a long journey the check engine light will fairly regularly appear around 70km from the start of the journey. I suspect a vehicle speed sensor fault, but I want to confirm this before trying to fix it.
There appears to be no adverse effect on vehicle running but I'm planning further work (install of remote starter, alarm & Quick Change) and would like to ensure the car is error code free before introducing new variables.

I've attached a pic which is fairly self explanatory. I guess I need some help identifying the wires I've found behind the kick panel and confirmation that I'm plugged stuff in correctly to obtain the codes.

In case it's relevant, see my other thread about a key barrel fault preventing the key being turned to the lock position.

I also have an ECU Tune cable here (borrowed from Daniel) and Evo Scan software. I mentioned that in case that could be used to extract the engine codes.