I have a strange problem with my lights.

When I turn on my lights, I only have sidelights and no headlights or beam. After driving for 10 minutes or so the lights would just come on. Once on they never went off. If they were on, and I leave them on and restart the car, they go off again. They now aren't really coming on at all.

I have taken the car to 2 garages but neither have been able to identify or fix the problem. They have checked all the obvious and do not think it is the switch system. The mechanic said that when the switch is on, there is only earth behind the bulbs. They have been able to provide power and all the lights worked - so bulbs etc are fine.

I rang up a garage today who, from what I described, said that it sounds like the dim dip controller. Would this have been an obvious thing to check? Should I ring them to ask if they checked it? Also, I went to get a Haynes manual, but they don't have one. Anyone know where the dim dip control box is? 1998 Terios

Many thanks