assuming your car is connected to the caravan,make a test light out of an old bulbholder with two wires attached. remove the bulb from caravan lamp. put one wire from the test llight to the body of the lamp(metal part). connect the other wire to the centre connection inside the lamp this will check for power to the light, if the bulb doesnt light check the same way behind the lamp unit, you may be able to get to it from inside the van. once you find the bulb lights the power side is ok, the problem could be the earth or metal part of the lamp. this can be checked by holding a longer piece of wire between both metal parts of the two rear lights. if this works you need to connect a wire somehow to the metal part of the lamp and another earthing point on the body or chassis.
brian moore, October 2005
