this happened to my 110 td5 (2004), the dim dip relay packed in, ( Lucas 13DA YWC 10050) it is behind the speedo, the resistor pack is inside the drivers side wing. The dim dip relay can be bypassed by unplugging it and inserting a wire with 2 male spade crimps into the relevant socket holes. If you require a new relay I do have some new ones!