7 pin trailer plug

7 pin trailer plug: wiring, and every other necessary thing to know

Some of the most typical harnesses found on trailers are7 pin trailer plug. The necessary running lights, turn signals, brake lights, and ground for the trailer are provided by 7-ways. A 12V hot lead, electric brakes, and reverse lights are also provided on three more pins.

One of the parts of your towing setup that can be the scariest is the trailer wiring, but it doesn’t have to be. The majority of us aren’t electricians, but that doesn’t mean we can’t wire a trailer. That’s why in this article we’ll be discussing the installation and every necessary stuff about 7 pin trailer wiring.

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7 pin trailer plug

  • How to wire a 7 pin trailer plug wiring?
  • What is the Color Code for 7-Way Trailer Wiring?
  • What Size Wire Gauge is Used for a 7-Way Wiring Harness?
  • what to do When Finished with the wiring?

So, let’s begin!


How to wire a 7 pin trailer plug?

First, let’s get into the step-by-step process of wiring your trailer with a 7-way connector.

Wiring our trailer

Prepare for Trailer Wiring Installation

  • Initially, confirm that you have everything necessary to wire your trailer, including:
    • Junction box for wiring organization and security
    • A package of breakaway cables in case your trailer disconnects
    • An electronic brake controller for trailer braking
  • You can buy trailer lights or utilize a full trailer light kit, which will include the required wiring if you need to replace one or more of your lights. Before starting the new installation, remove the old lights.
  • Use a 7-way harness instead of replacing your lights if you don’t need to.

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Find or install the junction box

  • If your trailer already has a junction box and you’re changing the old wiring, Locate the junction box on your trailer (it’s usually near the front) and take off the cover if you’re replacing the existing wiring. Each terminal’s nuts should be removed.
  • Find an appropriate installation place if it’s a new junction box, such as the inside edge of your trailer tongue. Your wires should be able to reach the box, but they should be far enough away from other components that they won’t interfere with them.
  • You can simply connect the new wire harness to your trailer’s current wiring if you don’t have a junction box or don’t want to install one.

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Make Trailer Connections

When you’re with a junction box;
  • Remove the nuts from each junction box stud if all you are doing is attaching a new 7-way connector. Remove each terminal from the junction box if the wiring needs to be replaced, and then start disconnecting the old wiring.
  • Trim any extra wiring from the new cable, then use a crimper to remove the insulation from the wires. After that, attach ring terminals to the fresh wiring. Place the terminals (ground wire to the ground wire, brake wire to brake wire, etc.) onto the junction box’s matching studs. When finished, put the nuts back in place.
  • Use wire clips to secure any extra wire.

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When you’re not with a junction box
  • You can utilize butt connectors and a heat gun to make your wire connections if you’re not utilizing a junction box and are just joining the new 7-way to your old wiring.
  • Use wire clips to secure any extra wire.

NOTE: Check the manufacturer’s instructions for any wiring harness you use. The instructions will identify the function of each wire. You won’t always be able to rely on color alone to match up wire functionality.

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Now that the trailer is connected It’s time for;

Wiring our vehicle

Prepare for Vehicle Wiring Installation

If you have a 7-way connector
  • Great if your car already has a 7-way connector! You’re ready to go once you’ve plugged the trailer’s end connector into the vehicle’s end connector.
If you have a 4-way connector
  • The simplest method to add a 7-way to a car with a 4-way connector is using an adapter kit like the ETBC7, which comes with everything you need to change your 4-way into a 7-way. Before connecting, examine the wires in your car to make sure they work with a circuit tester. To ensure you have the correct wire, turn on each function (turn signals, brake lights, etc.) in turn and look for a corresponding signal from the circuit tester.

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If you don’t have a connector
  • Installing a 4-way plug and using an adapter is the simplest approach to installing a 7-way plug if your car has no connectors of any type. Consult our installation instructions here for assistance. Check out our tutorial here for thorough directions on installing an ETBC7 kit.
  • If you are splicing or clamping wires together, take the time to verify the functionality of your vehicle’s cables as well. Before connecting, make sure each wire serves its intended purpose by consulting the owner’s manual or using a circuit tester. The wiring system of your car is typically accessible with a circuit tester at the back, behind the taillights.
  • To ensure you have the correct wire, turn on each function (turn signals, brake lights, etc.) in turn and look for a corresponding signal from the circuit tester.

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Make Vehicle Connections

  • The existing lighting in your car will either be plugged into, clamped into, or spliced into by your electrical harness. Depending on what is available for your vehicle model, the connection type will vary. Below, we’ll go over each step in further detail.

A few general guidelines and notes

  • Use a mounting bracket to secure the vehicle connector to the car if it is located underneath the vehicle. By doing this, damage that might result from leaving the connector hanging will be reduced.
  • To assist prevent corrosion, apply a little amount of grease to all electrical connections, including the connector and the plugs on your car.

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4-way to 7-way adapters
  • Your trailer brakes and battery lead will each require two additional pins, which an adapter will add to your existing 4-way plug. We’ve put together adapter kit # ETBC7, which contains all of the connectors, wires, and circuit breakers required to install a 7-way adaptor.
  • You will need to attach an additional three wires after plugging the adaptor into your 4-way.
  • You’ll run one of these wires—typically blue, but occasionally black—to the output of your electric brake control. Through additional wire and butt connections, a different wire (usually black or red) is run to the positive terminal of the battery.
  • Before connecting, check the function of the wires with a circuit tester.

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plug-in style
  • Some car manufacturers essentially “pre-wire” you’re car so that the wires are accessible and ready to attach. No cutting or splicing is necessary when using T-connectors like this one; they just plug into the existing wiring in your car.
  • Typically, the plug-in location is somewhere under the car, behind the paneling in the cargo area, or close to the taillights. To access the plug, you might need to remove your trim access cover, scuff panels, taillights, etc.

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splice in style
  • Although hardware kits aren’t quite as practical as the other types, splicing into your car’s wiring is actually easier (and less frightening) than it seems.
  • One of three approaches should be used to connect your wires after you’ve confirmed their functionality (using your owner’s manual or a circuit tester).
  • The best approach to join wires is by soldering. Use a soldering gun to simply solder your wires together for the most durable, dependable connection. Heat shrink tubing should be used to shield the soldered connection.
  • Heat shrinks butt connectors and a heat gun are the next best thing if you are uncomfortable soldering wires.
  • Using a quick splice is the quickest, simplest technique to connect wires. A metal piece is quickly spliced into two distinct wires to join the circuit. NOTE: The simplest—yet least reliable—method of connecting wires is to use quick splices.

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What is the Color Code for 7-Way Trailer Wiring?

There are several wiring harness color codes for different industries. The standard wiring used in the RV industry is distinct from SAE (Society of Automotive Engineers) standard wiring. The criteria for both are mentioned below.

SAE Standard

  • Green: Right turn/brake light
  • Yellow: Left turn/brake light
  • Brown: Tail/running lights
  • White: Ground wire
  • Blue: Brake controller output
  • Black: Battery hot lead
  • Purple: Reverse lights

RV Standard

  • Green: Tail/running lights
  • Yellow: Reverse Lights
  • Brown: Right turn/brake light
  • White: Ground wire
  • Blue: Brake controller output
  • Black: Battery hot lead
  • Red: Left turn/brake light

Unsure about the precise functions of each wire? The simplest way to determine it is to confirm each wire’s functionality using a circuit tester.

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What Size Wire Gauge is Used for a 7-Way Wiring Harness?

For the turn signal, stop, reverse, and running light wires on a 7-way trailer plug, 16 gauge is the minimum recommended wire size. The recommended minimum gauge for the hot lead wires for the battery, braking power, and ground is 12.

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what to do When Finished with the installation?

It’s a good idea to plug the two ends of your trailer and car together after wiring them both, then test the operation of each wire. Make necessary alterations. You’re fine to go if everything lights up when it should!

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7 pin trailer plug FAQs

Are all 7 pin trailer plugs the same?

This critical question has a negative response. First off, not all 7-pin trailer plugs are wired for RVs; there are many varieties of them generally. The fact that not all manufacturers color-coordinate their plugs in the same way is also crucial to understand.

What is a 7 pin trailer plug called?

This is typical for RVs and other large trailers that have additional loads in addition to the standard brake/turn signals and taillights. SAE J2863, Automotive Trailer Tow Connector, is the document that outlines the standard.

What is a 7 pin trailer plug used for?

The 2-inch-diameter 7-Way Trailer Plug has one additional pin for an auxiliary 12-volt power source or backup lighting. It is typically used to tow open and enclosed car carriers, dump trailers, utility/landscape trailers, heavy-duty cargo trailers, aluminum trailers, and equipment trailers.

What is the difference between a 7 pin and 12 pin trailer plug?

Most conventional box trailers, smaller boat trailers, and basically any application that doesn’t require any accessories to be run while the trailer is in operation may all be powered by a 7-pin connector. The extra five pins on 12-pin trailer connectors can be used to run accessories.

How many types of trailer plugs are there?

They connect five, seven, or twelve wires from your car to your caravan or trailer, hence the names five, seven, and twelve-pin plugs. As a result, when you switch on your car’s indicator, the first pin transmits the signal to the trailer indication and turns it on.

Is 7 pin flat or round?

Round and rectangular (flat) 7 pin plugs and sockets are also produced, and there are several sizes for the round 7-pin. And although a tiny round 7-pin can be plugged into a large round 7-pin, a flat 7-pin can be plugged into a flat 12-pin, and so forth.

How many wires does a trailer plug have?

Four: The right turn light is green. For a left turn signal, use yellow. Brown is for the trailer’s taillights, and white is for the ground. Together, these four different kinds of cables make up “four-way wiring.” For the majority of light-duty trailers and boat trailers, four-way wiring is appropriate and relatively widespread.

Does a 7 pin trailer plug charge battery?

The Tow-In-Charge powers your additional trailer electrical requirements while also charging your 12-Volt batteries using the 7-prong wiring harness battery feed.

How many pins does a trailer plug have?

There are two primary types of trailer connectors: 7 pin and 13-pin. Both are widely employed across Europe. The necessity for more lights on the caravan or trailer being pulled and the complexity of automotive electrical systems led to the development of the 13-pin connector.

That’s all for this article where the following questions about 7 pin trailer plug were discussed;

  • How to wire a 7-pin trailer plug wiring?
  • What is the Colour Code for 7-Way Trailer Wiring?
  • What Size Wire Gauge is Used for a 7-Way Wiring Harness?
  • what to do When Finished with the wiring?

I hope it was helpful, if so, kindly share. Thanks for reading.