trailer connector
plug & socket
maintenance

Part of your regular trailer maintenance should include checking that the plug & socket wiring connectors are in good condition. The connectors are mostly forgotten until the trailer lights are checked before driving off, then the search begins to find the fault.

main cause

The split in the pins of the plug (male fitting) tend to close up, particularly if you wiggle the plug from side to side when pushing it in or pulling it out. You can open the pins a little with a knife blade or small flathead screwdriver so they will make contact with the socket (female fitting). Be careful not to use too much force or open the pins too wide as you can snap one half of the pins off.

I have successfully replaced a pin removed from an old plug. They have a knurled fitting in the plastic so you just have to carefully align before pushing home.

the slot in all pins open	electronic cleaning solvent

Another main cause is the earth pin can be causing a bad earth. This needs to be checked for a build up of verdigris or the bluish-green coating inside the socket (female fitting). A spray with an electronic cleaning solvent into the sockets every now & then solves this problem. Whatever type of cleaner you use, make sure it is suitable to be sprayed on plastic. The pins & sockets are stainless steel so should not rust.

The exposed wires in the casing of the plug & socket can oxidise over time. If this is the case you will need to cut a little off the wires so they are clean & bright, strip a little insulation & reconnect with a small flat screwdriver. A little spray of silicone now & then will stop this problem.

no dust has built up over dirt roads using silicone spray

prevention

Spraying WD-40 will lubricate the plug & socket allowing the two to be easily connected or separated, however WD-40 attracts a build up of dust. Silicone spray is the perfect lubricate here & can also be use on tent zips, the towing hitch or anything that moves. There are a number of silicone spray brands on the market.

You will note in the photos above there was no dust build up having travelled over hundreds of kilometres of dirt roads after spraying with silicone. Also you will see there is a little damage to a couple of pin slots that have been opened slightly with a small screwdriver. 

our set up

We use a 12 pin plug, the 7 pin section is used as it should for trailer lights & electric brakes etc, while the larger 5 pin section is a matter of convenience. Power & reverse camera is wired through these pins so only one trailer connection is used, along with an Anderson connector for the DC to DC charger in the camper trailer.

The pins of a 7 pin trailer plug with fit into the 7 pin socket section of a 12 pin socket on the vehicle. Handy if you get a loan of your mates box trailer.


further reading

trailer wiring diagrams https://www.campertrailers.org/trailer_wiring_diagram.htm

 

article by Rob
 

november 2023