MX5Ireland

Hi all I was driving today with my lights up with no lights switched on and the drivers side light started to go up and down on its own accord, I flicked the switch to put them down and the drivers light still went up and down on its own, I turned the engine off and no good, I got out and disconnected the battery, reconnected the battery and the light stopped flicking up and down in the closed position. If I had a bad connection at the switch surely I would have both lights going up and down.
Anybody come across this problem before?

Spray a bit of wd 40 in the headlight motor connectors, prob have water in there.
Also, check your grounds under the washer bottle.

In order for to pop up and down it must be getting power supply from somewhere ,ie switch maybe??