Customers original complaint was dipped beam headlights very poor.He called one of the breakdown guys,as he thought there may be some issue with the battery/charging/alternator circuit.Breakdown man said possible battery/alternator/wiring fault(what else would they say?)take it to a specialist.I carried out a few basic checks.Battery ok.Charging voltage ok no load at idle.Re-test system under load.turn on headlights,no dip beam.Surprise,surprise,both headlamp bulbs blown!!!.