My instrument lights have a intermittent fault where the dials sometimes don't light up on turning on the ignition. Turning off and turning on again doesn't make any difference. Usually they come on after a couple of minutes, but yesterday they switched themselves off just as I got home! All the warning lights are working as they should and the instrument needles are lit ok. If I turn the side or headlights on the instruments light up as they should but they turn off when the side or headlights