After possibly the worst soldering job ever performed the ecu is back in the car and the 4ws light has gone off with both engine starts i tried. gonna take it for a drive in a sec and hopefully all will be well!
EDIT: it appears to be fixed!! just thrown it around some country lanes for a while and it was working a treat, then when i got home cut the engine and restarted it and the light went straight off. im am well happy!
Thanks so much to everyone who contributed to this thread and helped me out, i couldnt have got it sorted without the help and advice from you guys!

...Although it does still pull to the left a little.
