Brake lights not working and indicators only working on one side? That's a combination that doesn't exactly inspire confidence in the driver behind you. Luckily, most electrical faults are minor and easy to fix, as long as you know where to start. This article will walk you through the most common electrical connections for trailers, as well as lights and glitches you should keep an eye on.
7-pin socket – traditional standard
Older and simpler trailers as well as small trailers usually use a 7-pin plug. This connection includes all the basic lights needed for towing a trailer:
- Headlights
- Brake lights
- Turn signals
- Fog lights
The 7-pin socket works well with standard trailers that do not have separate accessories.
13-pin socket – a newer and more versatile option
The 13-pin plug has all the same functions as the 7-pin socket, but it can also be used to transmit additional functions, such as:
- Reversing light (common in trailers subject to inspection)
- Power supply for an electric winch, caravan battery, or refrigerator, for example
If you want to take advantage of the power supply capabilities of the 13-pin connector, your car will usually need to have a separate power supply kit in addition to the 13-pin electrical kit.
The most common electrical faults in trailers
The most common electrical faults are worn out plugs and wires, poor grounding, burnt-out bulbs, and oxidation caused by moisture. By checking these, you can usually quickly find the source of the problem.
LED lights can also cause problems, especially when they lack the necessary resistors. Some cars, particularly those with power control, may not recognize the bulbs correctly and may cut off the power supply due to insufficient power consumption.
LED lights and compatibility
Traditional light bulbs and LED bulbs with a pre-resistor will work in virtually all cars. However, LED lights without a pre-resistor will not always light up, especially in cars with power control in the tow bar's electrical system.
If the LED lights on your trailer are not working, the problem can be solved by
- adding pre-resistor
- or replacing the tow bar's electrical system.
The reason for this is usually that the current control cannot supply the correct amount of current to the LED lights without a pre-resistor.
If the trailer's electrical system is causing more headaches than light and the fault is suspected to be on the car side, the experts at Koukkupaja will help you get up and running again!
