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What You Should Run Through Your 12 Pin Trailer Plug

What You Should (and shouldn't) Run through your 12 Pin Trailer Plug

Your trailer plug is the electrical lifeline between you and your caravan. Making sure it is wired up correctly, and operating as intended, should be one of your top priorities as a caravan owner. For those new to caravanning, it might be a little confusing as to why your trailer plug is so important, so we thought we’d explore the 12 pin trailer plug a little further.

7 Pin vs 12 Pin

Many vehicles come with a 7 pin socket as standard, which for most people is all you need for basic towing. However, if your caravan is fitted with a brake away system, electronic stability control or you want to run a fridge power feed, you will need to replace it with a 12 pin socket. The 12 pin socket not only allows you to wire up additional accessories, but it also allow for more versatility when towing. For example, a 7 pin plug (on a caravan) can fit into a 12 pin socket (on a vehicle) but it can’t be done in reverse.

Standard Wiring for 12 Pin Trailer Plug

Although there are several options for how to wire up a 12 pin trailer plug, we usually recommend the following configuration.

  1. Left indicator
  2. Reverse
  3. Earth
  4. Right indicator
  5. Electronic Brakes
  6. Brake lights
  7. Park lights
  8. Isolated power supply (For Fridge or Accessories)
  9. Isolated power supply (For Fridge or Accessories)
  10. Earth
  11. Spare
  12. Isolated power supply (For Fridge or Accessories)

In most cases we will also install an Anderson plug or two depending on the vehicle and caravan. 

  • Grey Anderson plug: Isolated Charge feed from vehicle start battery.
  • Red Anderson plug: Direct 12v supply suit ESC Operations.
What You Should and Shouldn't Run Through Your 12 pin Trailer Plug
Anderson Plug


Why Use Anderson Plugs?

If you are wanting to run a charge feed through to your caravan batteries, we will always recommend installing an Anderson Plug on your towbar for this purpose. The reason for this is that your 12 pin is not designed to handle a charge feed. A 12 pin plug can only take up to 6mm wire, which is not suitable for a charge current. In the worst cases, trying to run a battery charge feed through your 12 pin plug can lead to pins melting together, destroying the plug and socket in the process. 

In some cases we also install an Anderson Plug for connecting the Electronic Stability Control (ESC). Anderson plugs are usually are a bit more secure than your standard trailer plug, so we recommended them when a stronger connection is required. If you intend to head a bit off the beaten track, we would definitely suggest installing an Anderson plug for your ESC. 

To ensure the two plugs are not mixed up with one another, we will usually install two different coloured Anderson Plugs. The different colours are also designed in a way so they can not connect into a different colour. Red can only connect to Red and Grey to Grey. This ensured there are no mix ups when hitching up to hit the road. 

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