How To Wire And Install A 4 Pin To 7 Pin Trailer Adapter

Does your trailer have a 7 pin adapter and you only have a 4 pin connector? Perhaps you want to know how to connect the two before your next adventure?

Or maybe you want some help wiring them for an easy connection, but don’t know where to start? Whatever your question might be, we have the answer for you! 

How To Wire And Install A 4 Pin To 7 Pin Trailer Adapter

When it comes to powering your trailer and its RV functions, many of us can freeze and panic. But it isn’t as difficult as you might think. You can worry that a 4 pin and 7 pin adapter just aren’t compatible and the stress sets in, how will you tow your trailer now? 

But there is no need to worry! As you can use a 4 pin connector to tow a 7 pin trailer with ease. Just keep reading to find out how to do it! We’ve got plenty of tips and information that will make this a smooth process for you!

What’s A 7 Pin Connector?

Before we dive into the article, let’s have a recap for those in the room that need it! A 7 pin connector has three extra features than a 4 pin connector.

It can power your operating lights, brake lights, left and right signal lights, and ground, but a 7 pin can also run your electric brake, reverse lights, and a 12-volt system! 

To do this, a 7 pin connector features 7 power connection options that can run your trailer and its safety equipment without any issues.

Now, as good as this is, you might not need one. If you already have a 4 pin connector installed and running fine, then there might not be any need to install a 7 pin connector too. 

In some cases, you might have both a 7 pin and 4 pin connector installed on your bumper. A 4 pin might not work if you try and plug it into the 7 pin option.

You would need to install it into the 4 pin option or purchase an adapter that would allow you to make the connection between the two-pin connectors. 

Now that we have established what a 7 pin connector is, let’s move on and learn more about these trailer plugs before finding out how to connect the adapter! 

What Does A 7 Pin Trailer Plug Do?

For those that aren’t sure why you need a 7 pin connector, keep reading! You won’t always need a 7 pin connector, but there are some instances where it will be needed and you must be prepared for these instances. 

When towing a trailer, you need to have working lights. This is the law in most states, and you will find that your trailer needs to meet the requirements set in these laws to avoid any fines or being pulled over.

You can check the laws in your state online, or by contacting your local DMV office. We recommend doing this before setting off with your trailer to avoid any issues on the road.

If you are traveling to a different state, you will want to check their laws too, to ensure that your journey will be smooth and problem-free! 

A 7 pin connector will help you here and operate most of the lights on your trailer. Your trailer has a few different lights and each comes with its own color-coded wire. You can connect the wires you want to the connector and it will then power the lights on your trailer.

You can choose which lights to connect, such as your turning signals, aux power, brake lights, electric brake, reverse lights, or taillights. 

You must connect your wires correctly to ensure that the connection is secure and that your lights will be powered while you tow your trailer. It’s worth testing them before setting off so that you have peace of mind while you drive.

But don’t worry about that, we can walk you through the process to wire and install your connector with ease! 

What Is A 4 Pin Connector? 

We’ve mentioned them a fair bit throughout this article, so you might be wondering what a 4 pin connector is? Well, it’s similar to a 7 pin connector, working to provide electrical power to your trailer’s safety lights.

But unlike the 7 pin connector, it comes with fewer power options. That’s right, it comes with 4 options rather than the 7 that a 7 pin connector offers you. 

In the instances where you don’t need all seven options, a 4 pin connector comes in handy! Typically, a 4 pin connector won’t control the aux power, reverse lights, or electric brake. If you want these to be powered, then you are better off with a 7 pin connector. 

Usually, a 4 pin connector will control your tail lights, right and left turning lights, and your right and left brake lights. You will want to ensure that the ground wire (often white) is connected first before connecting the other wires to power your lights. 

So should you choose a 4 pin or 7 pin connector? Well, if your trailer has electric brakes and no aux or backup power, then it’s best to go with a 7 pin connector. This will provide you with the power that you need and keep your lights running. 

It’s worth noting that you might need to remove the taillight cover to find the right wires and connect them if you have an older vehicle. Usually, most vehicles made from the 1990s and onwards have factory-installed connectors making them far easier to tow.

As time moves on and older vehicles are phased out, you won’t need to worry about removing tail light covers to access the necessary wires. 

What Do The Different Wires Mean?

Now, if you have never used a connector before you might be confused about the different color wires and what they do. And that’s okay, it is confusing for everyone the first time that they use a connector.

But to make your life a little easier, let’s look at two wires that confuse people on the trailer and trailer plug to find out what they do and make your life a little easier. 

Brown Wire On A Trailer 

Brown Wire On A Trailer 

The brown wire on your trailer is usually responsible for the taillight, whether you have a 4 or 7 connector. There are exceptions to this rule, of course, but typically the brown wire is for the tail light wire. 

One exception is the 7 way RV blade style connector, which uses the green wire to control the taillights instead. The brown wire here is responsible for the right turn signal and brake light. 

As we said, this is an exception to the rule, so unless you use this connector, you can assume that the brown wire is responsible for the taillights.

Be sure to double-check in the instruction manual before connecting the wires to save you the trouble of having to disconnect and reconnect them! 

Blue Wire On A Trailer Plug 

Moving onto the trailer plug, we have the blue wire which is known to trip people up. Thankfully, there is less confusion here and it is far more consistent. On most pins, the blue wire is in charge of the electric brake.

Now, although we said it is more consistent, there is an obvious exception to the rule. Can you guess what it is? 

Yes, it’s the 4 pin connector! Typically, these connectors don’t operate an electric brake, so do not have a wire that is responsible for it. Remember, a 4 pin connector will operate turning signals, brake lights, and taillights, the most important functions that you need when towing a trailer. 

There is also another exception to this rule, and that is the 5 pin flat. On these connectors, the blue wire operates the reverse lights. A 5 pin flat connector will not operate your electric brake, so you must consider this when deciding if it is the right connector for you or not. 

Now, you might be wondering, is there a wire without any exceptions? Well, the white wire is always the ground wire. There are no exceptions to this rule, you can always count on the ground wire to be white. It’s always the easiest wire to identify too! 

How To Hook Up A 7 Pin Trailer To A 4 Pin

Now that we have learned about the connectors in some detail, let’s look at how you can connect a 7 pin trailer to a 4 pin connector. You can do this in three easy steps! Keep reading to follow our steps and make the connection with ease. 

Step 1 – Ground Your 4 Pin Connector 

This will always be your first step, regardless of the trailer and connector that you have. Without a proper ground, the connector will not work as it won’t have a completed circuit for the energy to flow across. 

If you have any issues grounding your connector, be sure to check the instructions in the connector’s manual. Usually, these instructions will be more accurate than those online and will help with your model.

You can also make use of online tutorials, but be sure to find ones that are using the same connector as you. 

Step 2 – Connect The Wires 

Next, connect the 4 pin colored wires to the matching wires on the 7 pin trailer connector. If you have any issues identifying the corresponding wires, you can check your instruction manual or follow along with an online tutorial. 

Step 3 – Decide What To Do With The Other Wires 

As you have a 7 pin trailer, there will be three wires left unattached. Here you have two choices, you can either attach them to your vehicle’s wiring or do nothing with them. If you aren’t going to wire them, then you will want to put crimps or wire nuts on them.

This will protect the ends of the wire and ensure that they aren’t damaged while you tow your trailer. 

If you have completed these steps, and the electric signal is hitting the adapter but not your trailer’s electrical system, then there is likely to be an issue with the trailer’s wiring. Usually, the issue is not with the adapter, but as we know, there are always exceptions to these rules! 

To check that the adapter is not to blame, plug the current trailer 7 pin connector into another connector to double-check, using a voltmeter.

It can be fun to chase down the problem and come up with a solution! When handling the wires, make sure you prioritize your safety at all times. 

How To Connect A 4 Pin To 7 Pin Trailer Adapter 

Connecting a 4 pin to 7 pin adapter isn’t too challenging! It is best to have the electrical entering the system through the connector and trailer’s electrical system. This should make your life a lot easier too! 

Next, you will want to connect the corresponding wires, ensuring that there is power being supplied to all of them. As you are using a 4 pin connector, there will be limited safety functions.

You won’t be able to power your electric brakes, the aux power, or reverse lights. You also won’t be able to run a 12-volt system like you can with a 7-pin connector. 

Now, a 4 pin connector is fine to use with a 7 pin trailer in a pinch, but if you want a connector to use regularly, we think it’s better to get a 7 pin adapter, so you don’t need to sacrifice your safety features! 

How To Wire A 4 Pin To 7 Pin Connector 

Before you go, let’s take a look at wiring your 4 pin to a 7 pin connector. It might take a few attempts to get it right, so don’t be disheartened, the more you do it, the easier it will become!

Be sure to have your user manual on hand to help you through the process and provide you with accurate information for your model. 

When wiring the 4 pin to a 7 pin connector, you will want to ensure that you connect the right wires. Usually, the colors will help you here and you just need to connect the same colored wires. 

But if they use different colored wires, you will want to track which function each wire goes to and use this to connect the correct wires. Don’t forget to make use of your manual here!

If you do find this difficult or are wary of doing it yourself you can enlist the help of a professional to walk you through the process! 

Final Thoughts 

And there you have it, wiring and installing a 4 pin connector to a 7 pin adapter or trailer isn’t as difficult as you first thought! You just need some patience, understanding, and the help of an expert if you run into difficulty!

Remember to prioritize your safety when handling wires and to use your manual for advice along the way! 

Madeline Cooper
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