Car trailers come in various sizes and weights and have various functions. All types have their own lights (which may differ depending on the type of trailer). These lights indicate the presence of the vehicle and the direction of turning, braking, etc. The light units are powered by a system on the trailer that receives power from the towing vehicle via a plug-in coupling, which can have either 7 or 13 poles (depending on the older or newer versions). The light clusters are flanked by red triangular reflectors on the rear and white ones on the front. The efficiency of these units is essential: we would like to remind you that, as of 2018, MoT tests for trailers with a total weight not exceeding 3,500 kg must be carried out at the same time intervals required for motor vehicles, motorbikes and mopeds – 4 years after first registration and then every 2 years. Private individuals are not allowed to make modifications or carry out miscellaneous work on light assemblies. Such jobs must be done by authorised workshops. Routine maintenance or temporary emergency work on the trailer is permitted.
WHAT YOU’LL NEED
WD-40® Multipurpose Product
WD-40 Specialist® Contact Cleaner
Screwdriver and pliers
Spare bulb sets
WD-40 Specialist® Super Release Agent
CHECKS TO BE MADE ON TRAILERS
Before embarking on a journey, it is a good idea to carefully check the functionality of the trailer’s light assemblies by connecting the electrical coupler, attaching the repulsor to the trailer hitch and starting the car. The functionality of the sidelights, stop lights and direction indicators should be checked. The surfaces of the assemblies should always be well washed (no violent jets of water) and cleaned as should those of the reflectors.
FAILURE TO SWITCH ON
If one or more of the lights on the trailer fails to light up, attention should first be paid to the 7- or 13-pin connectors that connect the electrical system of the trailer to that of the towing vehicle. With the engine and electrical services switched off, disconnect the connector and examine the insides of both components for any foreign material, oxidation or other damage. If necessary, the interior can be cleaned with a vacuum cleaner to remove infiltrated materials. Before reconnecting the two parts, it is advisable to spray the male and female poles of the two components with WD-40 Specialist Contact Cleaner, which effectively dissolves grease, dirt, dust and condensation on electrical or electronic equipment, including delicate materials. Its non-conductive, fast-evaporating formula leaves no residue and is compatible with all metals, plastics and types of rubber.
BURNT-OUT BULBS
If a bulb still does not light up, it must be replaced. This is done by disconnecting the trailer’s electrical system from that of the vehicle by disconnecting the 7- or 13-pin plug. The light assembly must then be opened. Depending on the model, screws with exposed heads will have to be loosened or snap-on covers will have to be opened. Once the bulb is located, it can be removed by disconnecting it from its socket with contacts. Before reassembly, spray all contacts and pins with WD-40 Specialist Contact Cleaner. Refit the bulb (identical to the one removed) and test its operation before reassembling the light unit.
WOBBLY LIGHT UNIT
The trailer’s light units are attached to the chassis using different systems. In many cases there are screws or bolts that secure this by connecting brackets, feet (or whatever) on the back of the light unit to the trailer body. If an assembly wobbles or vibrates, the cause must be investigated and the fasteners tightened if necessary. If these are blocked and resist disassembly, it is advisable to use WD-40 Specialist Super Release, which penetrates quickly and frees the mechanisms in a highly effective way. Its formula is also suitable in difficult cases of seizing and oxidation. It is water-resistant. If the screw or bolt fastening system is badly rusted, it is best to remove it and replace it with a new identical one. Before reassembly, it is a good idea to spray with WD-40 Multipurpose Product, which removes moisture, prevents rust and protects all metal surfaces. It even removes grease, tar and glue stains from any non-porous surface.
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