Same as mine! It means that 1 diode in the rectifier is defunked. I am still running, some 4 months after this fault was diagnosed, with both lights on. It means that only half of the charge is going to the battery. OK if you do not do much driving in the darkness, but as winter is coming there will be more drain on the battery, lights, wipers, heaters and demisters, so you may run into trouble then. Flat battery will happen when 2nd diode goes and no charge is the result. Hope this helps.
Mick Walter, November 2013
