Connecting trailer lighting: how does it work?

As well as ensuring correct connection, it is also important to choose the right lighting components. These include rear lights, marker lights, licence plate lights and side marker lights that are suitable for the type of trailer and its intended use. In our overview of LED trailer lighting, you will find more information about the various components and solutions for professional trailer applications.

In this article you will find:  

• A clear explanation using the various wiring diagrams
• Step-by-step guide to the safe and efficient installation of trailer lighting

Connecting trailer lighting – with a 7-PIN connector

The illustration below shows the 7-PIN connector wiring diagram. This illustration shows all seven different functions.

Wiring diagram for trailer lighting: 7-PIN universal 12-volt connector/junction box.

1. Connection/Terminal 1 (colour: yellow): Left indicator;
2. Connection/Pole 2 (colour: blue/brown): Rear fog light;
3. Connection/Pole 3 (colour: white): Mass (serving contacts 1 to 7);
4. Connection/Terminal 4 (colour: green): Right-hand indicator;
5. Connection/Pole 5: (colour brown): Rear light/side marker light and number plate right;
6. Connection/Pole 6: (colour red): Brake lights;
7. Connection/Pole 7: (colour black): Rear light/side marker lights left.

As the name partly suggests, the 7-PIN connector consists of seven different connections. In the image below, these connections are indicated by different colours. Using these colours, in combination with the information below, you can easily connect the trailer’s lighting.

What is the difference between a 7-pin and 13-pin trailer plug?

In the trailer lighting market, there are three types of wiring diagrams: the scheme for the 7-PIN connector, the 13-PIN Jaeger plug and the 13-PIN Multicon plug. Before we go any further, it is important to briefly explain the difference between the 7-PIN plug and the 13-PIN junction box.

A 7-PIN connector is intended for the basic lighting of a trailer. A 13-PIN connector also provides additional connections for functions such as reversing lights and an extra power supply. Which connector is required depends mainly on the functions fitted to the trailer and not directly on its size or weight.

The plug configuration required also depends on the lighting that is mandatory or recommended for the trailer. A 7-PIN connection is often sufficient for basic lighting, whilst a 13-PIN connection supports additional functions such as reversing lights. Would you like to know first which light functions are mandatory on a trailer? Then do read our article on the rules for trailer lighting.

Connecting 7-PIN connector

The 7-PIN connector variant is suitable for less complex towed items, such as a bike rack, trailer, boat trailer or horse trailer. Using the 7-PIN connector, you can connect the basic lighting on your towed item. This includes basic lighting within the LED rear light category (fog lights, indicators and brake lights). Although the 13-PIN junction box is more comprehensive, the 7-PIN connector still fully complies with the relevant standards.

Connecting 13-PIN connector

This connector variant can be seen as the ‘big brother’ of the 7-PIN connector. The 13-PIN connector is designed for more complex towed vehicles. Examples include caravans, advanced trailers, large boat trailers or large horse trailers. Just like the 7-PIN connector variant, this connector is also connected to your car. You can connect the connector to the trailer by inserting it into the socket beneath the tow bar.

The additional pins on a 13-PIN connector are used, amongst other things, for reversing lights, constant power supply and switched power with mass. This makes a 13-PIN connection suitable for trailers with additional lighting functions or extra electrical equipment. Where these functions are required, a 13-PIN connector is often the most logical choice in practice.

Characteristic	7-PIN	13-PIN
FeatureApplication	7-pin: Lighttrailers and luggage trolleys without additional electrical loads	13-pin Caravans, motorhomes and trailers with additional electrical loads
Featuresand Basic Functions	7-pin: Indicators, brake lights, position lights and rear fog lights, mass	13-pinIdentical
Featuresand extra functions	7-pinNone	13-pin Reversing light, continuous power supply (terminal 30), switched power supply (terminal 15), separate masses
SpecificationStandard	7-pinISO 1724	13-pinISO 11446

Choose the 7-PIN option for standard trailer lighting. Choose the 13-PIN option if the trailer has additional features, such as a reverse light or a continuous power supply for a caravan.

Connecting trailer lighting – with a 13-PIN Jaeger plug:

For the 13-PIN trailer connector scheme, see the image below. This image describes all thirteen functions of the Jaeger plug. Using this trailer wiring diagram, you can connect the lighting on the trailer.

Wiring diagram for trailer lighting: 13-PIN universal 12-volt connector/junction box.

Connecting a 13-PIN connector is very straightforward using the wiring diagram above. As shown in the image, this junction box consists of thirteen different connections. Just as above, we will also explain the various connectors on the 13-pin junction box below. For the visual learner, we have also included an illustration to provide a complete overview at a glance. Using this scheme, you can connect the lighting on the trailer correctly.

Thirteen connections 13-PIN connector (Jaeger)

1. Connection/Terminal 1 (colour: yellow): Left indicator;
2. Connection/Pole 2 (colour: blue): Rear fog light;
3. Connection/Pole 3 (colour: white): Mass (serving contacts 1 to 8);
4. Connection/Terminal 4 (colour: green): Right-hand indicator;
5. Connection/Pole 5: (colour brown): Rear light/side marker light and number plate right;
6. Connection/Pole 6: (colour red): Brake lights;
7. Connection/Pole 7: (colour black): Rear light/side marker lights left;
8. Connection/Pole 8: (colour grey): Reversing lights;
9. Connection/Pole 9: (colour brown/blue): Permanent interior lighting power wire;
10. Connection/Pole 10: (colour brown/red): Charging cable for caravan battery/refrigerator;
11. Connection/Pole 11: (colour white/red): No destination (possibly mass);
12. Connection/Pole 12: (-): No destination;
13. Connection/Pole 13: (black/white): Mass (serving contacts 9 to 12).

Connecting trailer lighting using a 13-PIN Multicon West connector:

The image below illustrates all thirteen functions of the Multicon West connector. Using this scheme, you can connect the trailer’s lighting correctly.

Thirteen connections 13-PIN connector (Multicon West)

1. Connection/Terminal 1 (colour: yellow): Left indicator;
2. Connection/Pole 2/54G (colour: blue): Rear fog light;
3. Connection/Pole 3/31 (colour: white): Mass (serving contacts 1 to 8);
4. Connection/Terminal 4/R (colour: green): Right-hand indicator;
5. Connection/Pole 5/58R: (colour brown): Rear light/side marker light and number plate right;
6. Connection/Pole 6/54: (colour red): Brake lights;
7. Connection/Pole 7/68L: (colour black): Rear light/side marker lights left;
8. Connection/Pole 8: (colour grey): Reversing lights;
9. Connection/Pole 9: (colour brown/blue): Permanent interior lighting power wire;
10. Connection/Pole 10: (colour brown/red): Charging cable for caravan battery/refrigerator;
11. Connection/Pole 11: (colour white/red): No destination (possibly mass);
12. Connection/Pole 12: (-): (possibly work lights);
13. Connection/Pole 13: (black/white): Mass (serving contacts 9 to 12).

The difference between the 13-pin Jaeger plug and the 13-pin Multicon connector

Within the 13-PIN connectors, there are two different systems, namely the Jaeger and Multicon West system. When connecting a 13-PIN connector, it is good to know that the two plugs have different poles. For this reason, we briefly light both connectors below.

Jaeger 13-PIN connector

The new 'standard' plug is the Jaeger plug. This connector has a bayonet connection. This ensures that the connector is firmly attached to the junction box and will not vibrate loose while driving. The bayonet connection is a valued connection, as it significantly reduces interference while driving.

Connecting the 13-pole Jaeger plug is very easy. Insert the Jaeger plug into the junction box at a 90-degree angle to the left. In this situation, the mounting block protrudes downwards. When it is in the junction box, turn the connector a quarter turn clockwise. Then turn it into the junction box and the bayonet connection is fixed. If you want to connect the Jaeger plug with 13 poles to a 7-PIN connector, this is possible with an adapter.

Multicon West 7/13-pin connector

In addition to the ‘standard’ 13-PIN connector, there is also another model, known as the Multicon West connector. This connector fits into both the 7-PIN and 13-PIN junction boxes. This makes the Multicon system suitable for use as both a 7-PIN and a 13-PIN solution. This Multicon connector can be useful if your trailer still uses an old 7-PIN connector.

It is worth noting, however, that the Multicon connector does not fit into a Jaeger junction box, nor does the Jaeger plug fit into a Multicon West junction box. When we look at the use of both types of connector, it is noticeable that Jaeger connectors are used more frequently than Multicon West connectors. The Multicon West system, on the other hand, is more commonly found in caravans.

Various adapter plugs for connecting junction boxes

Most vehicles nowadays feature a 13-PIN junction box, whilst most trailers and bike racks usually have a 7-PIN connector. To ensure these can be connected seamlessly, you can use an adapter plug. Adapter plugs come in various types. Below, we briefly explain the different adapter plugs in our range.

adapter from 13 to 7-PIN

The adapter that converts a 13-PIN connector to a 7-PIN connector functions opposite to the situation described above. If your vehicle is equipped with a 13-PIN connection, this adapter allows you to connect a 13-PIN connector. However, it is important to realise that in this case, only the functionalities associated with a 7-PIN connection will be active.

adapter from 7 to 13-PIN

The 7-pin to 13-pin adapter allows you to connect almost any electronic product to your vehicle's connector. If, for example, you have a 13-PIN caravan connection but a 7-PIN junction box, you can convert it with the adapter. In short, the sales adapter from 7-pin to 13-pin connector is meant to allow you to use a 13-pin connector, when your car is only equipped with a 7-PIN connector.

You can find the relevant product on our dealer portal via the following link: 7-PIN to 13-PIN adapter.

Frequently asked questions on 7-PIN and 13-PIN connectors

At TRALERT® we regularly receive questions about the 7-PIN and 13-PIN junction boxes. Below we have therefore listed these frequently asked questions for you.

When do I use a 7-PIN connector?

A 7-PIN connector provides only the basic lighting, such as indicators and brake lights. A 7-PIN connector is, for example, perfectly suited for bike racks or small trailers.

When do I use a 13-PIN connector?

The additional pins on a 13-pin connector are used when, in addition to the basic lighting, you also use, for example, reversing lights and rear fog lights. These two features have been mandatory on trailers, caravans, boat trailers and/or horse trailers since 10 July 2011. Since 2011, these vehicles have therefore been fitted as standard with a 13-pin junction box.

What types of 13-PIN connectors are there?

The 13-PIN connector variant has two types, namely the Jaeger and the Multicon West plug. These are used for different purposes. Of the two, the Jaeger junction box is the most common. Although the Multicon West is most often used with caravans.

A more detailed explanation of trailer lighting

If your question isn’t listed above and you’re looking for a suitable answer, read our comprehensive article to find out everything about trailer lighting.

Want to know about the regulations? Then read our article on the rules for trailer lighting. If you’d also like to know more about the international mounting and installation regulations for vehicle lighting, our explanation of ECE R48 provides further background.

The TRALERT® choice

If you’re looking for lighting for your trailer, we recommend this complete set from TRALERT®. The set includes 12V trailer rear lights, marker lights, licence plate lights and side marker lights, ensuring you can not only travel safely but also in style thanks to our carefully selected range.

Better Light Work Safer!