Air bag connections under seats.
previous post in another topic have had the same problem for ages, my light only comes on when i go about 60mph and my abs dosnt work when it does, but constantly kicks in at low speeds when the light is off. if you turn your wheels to full lock you can get a rough feel of the abs ring on the hub mines is badly chipped i have a new ring but have't got round to fitting it, cost of rings are about £10 - 20 i got one of ebay for £10, a sensor is closer to £50 i think
I would be pretty confident its the ring if when you brake hard you sometimes get a metallic feel through the pedal as well. On the non-sport clios, it means a new driveshaft though, as you cant get the rings for the non sports seperately.