Hi Tommy, I did read your thread yes - I've done the underseat connectors as you instruct. I left the battery off but it hasn't reset the light, I was a bit worried about your comment that it should reset on post 2004 cars, although mine is a 2004 car. It does have pre face lift windscreen wiper motor so I guess it might be a bit borderline. I'll have a look at the boot connector today too.
I actually ordered another lead from Ebay last night - wish I'd had your comment earlier rarebear - I would have got one of yours - if the one i've bought doesn't work I'll maybe get one from you. I didn't get the one you recommend Tommy, but it was one someone else recommended on here somewhere so who knows?!