[chrisdc]

Ok, had a look, I see plugs going into some sort of module encased in white plastic. I'll disconnect everything and take the module out for a better look. Presumably this is best done with the battery disconnected.

In case this helps anyone, there are 2 plastic plugs that hold a bit of carpeting in place below the glovebox area. I could feel them, but only see them using a mirror. These plugs are a 2 piece design with a circular centre pin flush with the head of the plug. Just push the centre pin in as far as it will go (I used a wooden chopstick). That will allow the plug to be removed without the need for any force. Actually quite a clever design once you know how it works.