When is a warning triangle required at the rear of a towed vehicle?
Explanation
A vehicle being towed has to be visible to everyone else on the road, which is normally done with the hazard warning lights. If those lights are missing or not working, you must use an alternative — fix a warning triangle to the rear of the vehicle.
KET reference: KET 216: if a towed vehicle has no working hazard warning lights, a warning triangle must be fitted to its rear.