my mate just had a similar problem on his late classic.as far as i am aware the abs and traction control both work on the same sensors. it turned out his problem was air gaps between the sensor and wheel hub had opened up. these required a gentle tap to re seat them and a faulty brake light switch. he had the faults tested the local independant and the computer showed the faults straight away. reset the ecu been ok since. or you could take it for a run and see if it clears itself. but take your time. i hope this gives you some ideas.