Ascertaining that the exterior lights on your caravan are working is an essential safety check before you hit the road. There are a few simple tests to complete which will get the majority of bulbs blinking in no time. These checks all presume that the lights have worked correctly with your car and caravan combination previously. Remember to turn on the car ignition before you start troubleshooting.

Start with the black 12N plug from the caravan to the car. This carries all the road-light connections. Check it is properly pushed home. A bad connection is the main culprit with lighting problems. Pull and refit the plug, and then retry the lighting.

If this has little or no effect, the plug may be dirty. Use emery cloth carefully to remove grime from the pins, and spray a bit of WD-40 on them. Also check for cable, socket and plug damage, and replace anything that needs it.

Use a test lamp to check whether power is reaching the socket. Clip the earth to the towbar and touch the probe to the centre pin of the 12N socket. If the lamp fails to go on when the car's sidelights are lit, the car may have a wiring fault that needs professional attention.

If you have a problem with a single light, the fitting itself needs investigation. Most caravan light lenses are secured with crossheaded screws. Carefully remove the screws and remove the bulb which doesn't work to check if it has blown. Replace as needed.

If you have a problem with a single light, the fitting itself needs investigation. Most caravan light lenses are secured with crossheaded screws. Carefully remove the screws and remove the bulb which doesn't work to check if it has blown. Replace as needed.