Ok, got new tyres put on at Costco, who insisted on rotating wheels front to back as it was "more than their job's worth" not to do so (Michelin trained to level 1!). Drove on to the motorway, then the orange ALB dash lamp came on. Got home and noticed the ALB sensor wire (at least that's what I think) on front driver side loose and probably been brushing against tyre. part of the sleeve had been rubbed through and the wire was exposed. Taped it up and secured it as it should have been, but beacon still on. I reckon they must have got some crud into one of the sensors or something. Sound reasonable? Comments and/or advice guys? gino