2000 Citroen C5 Flashing lights on the automatic transmissi

I am driving a Citroen Xantia, automatic transmission, front wheel drive, 2000 cc Turbo diesel.
On the control panel, there is an indicator which shows which gear the car is in, N, R, D, 3, 2, 1 and there are two settings next to this which light up, S for sport and a snowflake for winter driving. These two lights flash on and off all the time, but the car starts up easily, drives fine, speeds up and slows down as it should, but these lights flash all the time. Is there a mechanical problem that I cannot find, or that my mechanic cannot find? Could this just be a short circuit and nothing to worry about, or is my car about to die?