A common caravan problem that you might encounter is the caravan tail lights flickering or not working, maybe the left or right side is not working or the brake or stop lights aren’t working. This could be an indication that your trailer plug is an issue. The circuits that run through the 7 pins of a trailer plug are the indicators, left and right, the stop light, the brake light, and the brake line. There is always a line for the earth. There is often an empty pin (pin 2) which is mostly unused.
The trailer plug on a caravan or trailer whether it is round or flat is almost always left out in the weather. Water on the plug will lead to corrosion on the pins which can affect the connection and cause flickering tail lights or the lights to stop working. The first step in diagnosing your problem is to take a look at the trailer plug and check for corrosion.
If there is corrosion present (white or green build-up or rust) then cleaning off the corrosion with a bit of sand paper or dissolving with an electrical contact cleaner spray, might solve your problem. If the corrosion build up is significant and not able to be fixed by cleaning then replacing the trailer plug with a new plug may be necessary. New trailer plugs are inexpensive at around $10 and, for this reason, many of our travelling customers carry a spare as these commonly need replacing every few years.
After checking for corrosion, the next thing to do is take the cover off the plug which is held on with a couple of small screws and check the connection between the coloured wires and the screws that secure the wires. Ensure that the screw heads are nice and tight and all the wires are in there securely.
Next, take a look at the pin heads. These have a small split in the middle. Sometimes these can become squeezed together but can be separated gently so that they flare out slightly using a knife or small flat screwdriver. That makes the connection a lot tighter. As a note – the trailer plug connection to the vehicle should feel tight. As the pins are delicate we recommend that you don’t wiggle the plug in the socket when it is connected to the vehicle as this may loosen or damage the pins.
Lastly, we recommend inspecting the insulated cover over the wires where it meets the plug. You want the cover to protect the wires and you don’t want to see exposed coloured wires as this can lead to water getting into the plug.
When storing the van outdoors you may wish to protect the trailer plug by placing a plastic bag over the plug and securing it with a zip tie. Another option is to purchase a spare socket and put that on the plug while it is in storage.
If your caravan tail lights are flickering or not working then our 7 pin trailer plug maintenance guide may assist you to get the connection working again. If you are still experiencing difficulties then it may be time for a new trailer plug. At the RV Service Centre we stock all replacement trailer plugs in our show room and can assist you with fitting a new trailer plug. If the issue is not caused by your trailer plug our professional staff can diagnose and repair the issue. Give us a call or call in to the showroom.