If you need to replace or rewire an 8 pin trailer plug, this quick guide will help. An 8 pin plug is commonly used on many modern trailers and accessories, giving you the standard road lighting functions plus an extra pin, usually for a reverse light. Watch the video below for the step by step process, then use the notes underneath as a quick reference.
Looking for a 7 pin plug instead? If your trailer uses the older 12N setup, go to our 7 pin trailer plug wiring guide.
Watch: How to Wire an 8 Pin Trailer Plug
What an 8 pin trailer plug does
An 8 pin trailer plug is used on many newer trailers and towing accessories. It provides the standard road lighting functions, just like a 7 pin plug, but adds an extra pin which is typically used for a reverse light. That makes it a practical choice for many modern trailer setups.
- Indicators
- Brake lights
- Tail lights
- Fog light
- Reverse light or extra auxiliary function
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Step by step: wiring an 8 pin trailer plug
The full process is shown in the video, but the basic approach is simple if you work carefully and follow the correct pin layout for your plug and trailer.
1) Open the plug and prepare the cable
Unscrew the plug body, slide the outer parts onto the cable first, and strip back the outer sheath carefully so the inner wires are exposed.
2) Strip the individual wires
Trim and strip each wire neatly so you have enough bare copper to make a secure connection without leaving too much exposed.
3) Match each wire to the correct terminal
Follow the 8 pin wiring layout carefully and connect each wire to the correct numbered terminal. Because layouts can vary, always double check the pin diagram before tightening everything down.
4) Secure the cable and reassemble the plug
Make sure the cable clamp grips the outer sheath properly, not just the inner wires. Once the wires are secure, reassemble the plug body.
5) Test all trailer lights
Before towing, plug the trailer in and test each lighting function, including the reverse light if fitted, to make sure everything is working correctly.
Common mistakes to avoid
- Forgetting to slide the plug housing onto the cable first. This is one of the easiest mistakes to make.
- Using the wrong pin layout. 8 pin layouts can vary, so always double check before wiring.
- Loose terminal screws. Poor connections can cause intermittent lighting faults.
- Too much bare wire exposed. This increases the risk of shorts and unreliable electrics.
- Not testing the reverse light. The extra pin is one of the key differences, so make sure it works if your trailer uses it.
When is an 8 pin plug the right choice?
An 8 pin plug is often the right option for modern trailers and accessories that need the standard road lights plus a reverse light. It is commonly found on many newer trailers and is a sensible choice when your trailer has been built for 8 pin electrics from the start.
If you only need the basic road lighting functions, a 7 pin setup may still be enough. If you need more advanced auxiliary power, such as for caravans, a 13 pin setup is usually the better choice.
FAQs
What is the extra pin on an 8 pin trailer plug for?
In many cases, the extra pin is used for a reverse light, although layouts can vary depending on the trailer or accessory.
Is 8 pin better than 7 pin?
It depends on the trailer. If you need a reverse light or are using a newer trailer built for 8 pin, then it is the better option for that setup.
Can I wire an 8 pin plug myself?
Yes, if you are confident working carefully and using the correct pin layout. If you are unsure, it is safer to ask for help before towing.
Are all 8 pin trailer plugs wired the same way?
Not always. That is why it is important to check the specific wiring diagram for your plug, socket or trailer before making connections.
Need help with trailer electrics?
If you are not sure which plug type you need, or you would like help with trailer electrics, plugs, sockets or towbar wiring, speak to the GT Towing team.
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Read the full 7 pin, 8 pin and 13 pin guide or view wiring diagrams.