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How to Wire a 6-Way Trailer Plug (It's Easier Than You Think)

Although 6-way connectors are not as common as 4-ways and 7-ways, many trailers do use 6-way wiring harnesses. In particular, 6-way wiring harnesses are common on gooseneck and horse trailers.6-ways provide the required running lights, turn signals, brake lights, and ground for the trailer. They also provide two additional pins, a brake controller output and a 12V hot lead.Trailer wiring can be one of the most intimidating components of your towing setup, but it doesn't have to be. Most of us aren't electricians, but that doesn't mean wiring a trailer is beyond us. We'll walk you through the trailer-wiring process for 6-way plugs below, so you can get your trailer up and running in no time.
6-Way Connector on Trailer

What is the Color Code for 6-Way Trailer Wiring?

Before we get into the step-by-step walkthrough, we'll first go over the standard color code for 6-way wiring harnesses. This will make it easier when it comes time to make your wiring connections.
The color code for wiring harnesses can vary between industries, but the general standard for 6-way plugs is as follows:
  • Green: Right turn/brake light
  • Yellow: Left turn/brake light
  • Brown: Tail/running lights
  • White: Ground wire
  • Blue: Brake controller output
  • Red or Black: Battery hot lead
A NOTE ABOUT THE POWER AND BRAKE WIRESThe black power wire and blue brake wires are commonly switched. Be sure to check the instructions that come with your harness or use a circuit tester to verify function before connecting your wires.
6-Way Flat Connector Diagram

What Size Wire Gauge is Used for a 6-Way Wiring Harness?

The minimum suggested wire size for a 6-way trailer plug is 16 gauge for the turn signals, brake lights, and running light wires. The suggested minimum for the ground, brake power, and battery hot lead wires is 12 gauge.
6-Way Trailer Wiring Color Code
6-Way Trailer Harness Diagram

Wiring a Trailer with a 6-Way: Step by Step

Now that we have an idea what our wires do, let's get into the step-by-step process of wiring your trailer.

Trailer Side

Step 1: Prepare for Trailer Wiring Installation

Start by making sure you have everything you need to wire your trailer, such as:
If you need to replace one or more of your lights, you can purchase trailer lights or use a complete trailer light kit, which will come with the necessary wiring included. Remove old lights before beginning the new installation.If you don't need to replace your lights, you can simply use a 6-way harness.
Trailer Light Wiring Colors

Step 2: Locate or Install Junction Box

If you're replacing existing wiring and your trailer already has a junction box, locate it (it's typically near the front) and remove the cover. Remove the nuts from each terminal.If you're installing a new junction box, find a suitable location for installation, such as on the inside edge of your trailer tongue. The box should be close enough for your wires to reach, but away from any components it could interfere with.If you don't have a junction box and don't want to install one, you can simply tie the new wiring harness in with your trailer's existing wiring.
Junction Box on Trailer

Step 3: Make Trailer Connections

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.
WITH JUNCTION BOXIf you have a junction box and are simply adding a new 6-way connector, remove the nuts on each junction box stud. If you're replacing existing wiring, go ahead and remove the old wiring now by removing each terminal from the junction box.Cut any excess wiring from your new cable and strip the wires of insulation using a crimper. Next, crimp ring terminals onto the new wiring. Place the terminals onto their corresponding studs in the junction box (ground wire to ground wire, brake wire to brake wire, etc). When finished, reinstall the nuts.Secure any excess wire with wire clips.
Trailer Junction Box Wiring
WITHOUT JUNCTION BOXIf you're not using a junction box and are simply connecting the new 6-way to your existing wiring, you can use butt connectors and a heat gun to make your wiring connections.Secure any excess wire with wire clips.
Butt Connector Trailer Wires

Vehicle Side

Now that our trailer is hooked up, it's time to wire our vehicle. Let's get started:
Step 1: Prepare for Vehicle Wiring InstallationIF YOU HAVE A 6-WAY CONNECTORIf your vehicle already has a 6-way connector, then great! Simply plug the trailer-end connector into the vehicle-end connector, and you're ready to roll.IF YOU HAVE A 4-WAY CONNECTORIf your vehicle has a 4-way connector, the easiest way to add a 6-way is with an adapter kit like the ETBC6, which includes everything you need to convert your 4-way into a 6-way. Confirm the function of your vehicle wires with a circuit tester prior to connecting. Activate each function (turn signal, brake lights, etc.) in turn and check for a corresponding signal from the circuit tester to make sure you have the right wire.IF YOU HAVE NO CONNECTORIf your vehicle lacks any kind of connector, the easiest way to install a 6-way plug is to install a 4-way and use an adapter. For help on installing a 4-way connector, view our how-to guide here.
4-way to 6-way adapter
If you have a 4-way plug, add a 6-way with a 4-to-6-way adapter
Circuit Tester in Use on Trailer
Use a circuit tester to confirm wire function
Step 2: Make Vehicle ConnectionsYour wiring harness will either plug into, clamp onto, or splice into your vehicle's existing lighting. The type of connection depends on what is available for your vehicle model. We'll go over each process in more detail below.Some general notes and tips:
  • If the vehicle connector is under the vehicle, use a mounting bracket to attach it to the vehicle. This will help prevent damage that may occur if the connector is left dangling.
  • Use a small amount of grease on all electrical connections—the plugs on your automobile and the connector itself—to help prevent corrosion.
4-WAY TO 6-WAY ADAPTERSAn adapter will plug into your existing 4-way plug and provide two additional pins for your trailer brakes and battery lead. We've put together adapter kit # ETBC6, which includes everything you need to install a 6-way adapter, including the connectors, wiring, and circuit breakers.Once you plug the adapter into your existing 4-way, you will have an additional two wires that must be connected.One of these wires (typically blue but sometimes black) will run to your electric brake control power output. The other wire (typically black or red) will run to the positive terminal of the battery via additional wire and butt connectors.Use a circuit tester to test for wire function before connecting.
How to Wire Electric Trailer Brakes Diagram
Watch video installation of 4-way to 6-way adapter installation
PLUG-IN STYLESome vehicle manufacturers essentially "pre-wire" your vehicle so that your wires are easily accessible for connection. T-connectors such as this one simply plug into your vehicle's existing wiring, no cutting or splicing required.The plug-in location is typically near the taillights, underneath the vehicle, or behind the paneling in the back cargo area. You may have to remove your trim access cover, scuff panels, taillights, etc. in order to access the plug.
Trailer T-Connector
A T-connector connects to your vehicle's existing wiring via an OEM plug
SPLICE-IN STYLEHardwire kits aren't quite as convenient as the other styles, but splicing into your vehicle wiring is actually less difficult (and scary) than it sounds.After confirming your wire functions (using your owner's manual or circuit tester), connect your wires using one of three methods.Soldering: This is the best way to connect wires. Simpy solder your wires together for the strongest, most reliable connection using a soldering gun. Use heat shrink tubing to protect the soldered connection.Butt Connectors: If you aren't comfortable soldering wires, heat shrink butt connectors and a heat gun are the next best thing.Quick Splices: The quickest, easiest way to connect wires is by using a quick splice. Quick splices force a metal piece into two separate wires, thus connecting the circuit. NOTE: Quick splices are the easiest—but least reliable—wire connection method.
Trailer T-Connector
When FinishedAfter wiring up your trailer and vehicle, it's a good idea to plug the two ends together and test the function of each wire. Make adjustments as needed. If everything lights up when it's supposed to, you're good to go!
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