I have a 12 year old Sterling Europa 470 which has a rectangular red light (approx. 10x4cm) at the lowest mid-point of the caravan's back panel. This light had been flashing on and off like an indicator when the car and caravan are linked but stops when the 13 pin connector is detached. The problem has been fixed by removing the bulb and no other electrics seem to have been affected by doing this, but it would be good to know it's intended purpose. Any ideas?