Learning, Wiring,

How to Wire a Breakaway Switch (7 Steps & Test)

Correctly wiring a breakaway switch on a trailer is critical to guarantee proper engagement of the trailer brakes. I have compiled this guide to ensure you wire it correctly with diagrams and tips.

Quick Summary: You wire a break breakaway switch on a trailer after routing its wires to the junction box and attaching the switch and battery box. Then, wire as follows:

Breakaway switch – The blue wire will connect to the blue (break) wires and the white wire with the other white (ground) wires in the junction box. The black wire will connect to the batter’s positive terminal.

Breakaway switch battery – The wire connected to the positive terminal comes from the breakaway switch, and the negative terminal connects to a nearby ground point.

Junction box – Connect the two blue and 16-gauge black wires inside a Wago lever nut

Below, I will go into much more detail, so bear with me!

Method and Requirements

You will require the following items:

  • Wire cutter
  • Wire stripper
  • Wago lever nut (lever type wire connector)
  • Spade connector
  • Clamp multimeter (or DC meter)
  • Screwdriver or gun

Note that the exact procedure for your particular trailer might differ from the details in this article. It would be best if you referred to your trailer’s owner manual.

We will do the wiring in three places: the breakaway switch, the battery box, and the junction box.

Procedure for Wiring the Breakaway Switch

The breakaway switch is shown on the left in the picture below. The kit should also include a cable connected to a pin on the right.

After installing the breakaway switch on the trailer, which we will achieve at the end, insert the pin into the hole on the back of the switch, step 4, further below, under ‘Testing the Breakaway Switch,’ shows when it is removed for testing.

A man holding a cable breakaway switch
Video | SyEnsability

Step 1: Route the Wires

When installing the breakaway switch, insert the wires from it to the junction box, as shown in the picture below. The wires will connect as follows:

  • The blue wire will connect with the other blue wires (break leads) – see Step 5 when wiring at the junction box.
  • The white wire will connect with the other white wires (ground) – see Step 7 when wiring at the junction box.
  • The black wire – see Step 2 when wiring at the battery box.

A person routing the wires from the breakaway switch
Video | etrailer.com

Step 2: Mount the Breakaway Switch

A person mounting the breakaway switch
Video | etrailer.com

Procedure for Wiring the Battery Box

This particular battery box (in the picture below, with the front cover removed) is designed to mount on the side, but your one may differ as to where it will mount.

A person working on a battery box
Video | SyEnsability

The battery supplies power to the brakes if there is an emergency (trailer disconnecting).

Step 1: Mount the Battery Box

Mount the battery box.

We will connect the three wires from the battery box as follows:

  • The white wire is the ground wire. Connect it to the corresponding white wire on the trailer connection.
  • The black wire (which may be red) connects to the 12 volts from the tow vehicle to keep the battery charged.
  • The blue wire is the brake wire that connects to the brake circuit.

Step 2: Crimp and Connect the Black Wire

Route the black wire to the battery box and crimp a spade connector onto its end.

Crimp and connect black wires
Video | etrailer.com

Connect the black wire to the battery’s positive terminal.

Step 3: Crimp and Connect the White Wire

Crimp a ring connector onto one end of a small white wire and a spade or battery connector on the other end to connect to the battery. It should be long enough to reach from the battery’s negative terminal to a grounding point nearby.

Ring and Battery connector
Video | etrailer.com

Connect the ring connector end of the small white wire to the nearby grounding point (picture on the left below) and the battery connector end to the battery’s negative terminal (picture on the right below).

A man connecting wires to the battery's terminal
Video | etrailer.com

Procedure for Wiring at the Junction Box

Step 1: Open the Junction Box

The junction box is usually located at or near the trailer’s front inside a hitch area [Fig. 1].

Remove the screws to open it.

Step 2: Inspect the Junction Box Wiring

Inspect the junction box wiring [Fig. 2]. We will wire the right blue and black wires.

Inspecting the junction box wiring

Step 3: Identify the Right Wires

Identify the 2 blue wires [Fig. 3] and the right black wire [Fig. 4] to be connected.

A man holding the blue and the black wire

The blue wires are large, so they are easy to identify, but there are 4 black wires. The black wire to connect with the blue ones is the 16-gauge one, which should be thinner than the other three.

Step 4: Strip the Wire Ends

Strip the ends of the 2 blue wires and the 16-gauge black wire you identified in Step 3 using a wire stripper if they are not stripped already. Strip the insulation off approximately 3/8”.

Step 5: Connect the Right Wires

Separate the 16-gauge black wire [Fig. 5] from the other three black wires and insert them with the 2 blue ones into a wago lever nut [Fig. 6]. It does not matter which wire goes into which position; they will all be electrically tied together.

Connecting the right wires

You can use an ordinary wire cap instead of a Wago lever nut, but if you do that, twist the three wires together before twisting them further after putting the cap on. The cap must be large enough to accommodate the three wires, and the connection must be secure, i.e., the cap must not come off easily.

Step 6: Secure the Connection

Ensure the stripped ends of the three wires (2 blue and 1 black) are visible inside the wago lever nut as shown [Fig. 7]. They should extend to the end of the nut.

Also, ensure the levers in the wago lever nut are clamped down to secure the connection of the three wires inside [Fig. 8].

Securing wires

Step 7: Connect the Remaining Wires

Twist the remaining three (non-16ga) black wires with the red wire and cap them with a wire cap.

Also, connect the white wire from the breakaway switch to the other white wires in the junction box for the ground connection (see below). Secure both wire caps.

Connecting other wires in the junction box for the ground connection
Video | etrailer.com

Testing the Breakaway Switch

Testing the breakaway switch is essential to ensure it will work when needed in an emergency.

Step 1: Apply Power

To test the breakaway switch, apply power to the trailer, either by shore power, the 12V battery, or connecting to the tow vehicle.

Step 2: Use a Multimeter with a Clamp

Set a multimeter (or DC meter) to measure DC and put its clamp around the two blue wires in the Wago connector.

Step 3: Check the Reading

The reading should remain zero while the breakaway switch remains unactivated.

Step 4: Pull the Breakaway Switch

Pull the breakaway switch as if the trailer had disconnected from the tow vehicle. The picture below shows the breakaway switch being pulled while NOT wired (for demonstration). In a real scenario, the two leads would pull away from the switch and set the trigger inside the switch.

Pulling the breakaway switch
Video | etrailer.com

Step 5: Re-Check the Reading

After pulling the breakaway switch, the multimeter reading should be between 12 and 14 amps. If it is, then the wiring was done correctly. If it isn’t, re-check the wiring.

Rechecking results on Fluke multimeter

Step 6: Replace the Cover

Tuck all the wiring inside the junction box at the end and close the cover.

Tucking all the wiring inside the junction box
Video | etrailer.com


OminEco Trailer Breakaway Switch. https://www.amazon.com/OminEco-Trailer-Breakaway-Switch-Electric/dp/B09QSL2GT6/

Jayco. Emergency brake breakaway switch wiring. https://static.nhtsa.gov/odi/rcl/2019/RCRIT-19V516-3726.pdf

Video References:


etrailer.com youtube channel


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About Robert Gibson

Robert GibsonRobert Gibson is a skilled handyman and a trusted consultant in the home improvement realm, currently spearheading content creation for ToolsWeek. With a rich background in practical hands-on projects, spanning over two decades, Robert has mastered the art of troubleshooting and solving household challenges.

Known for his knack for breaking down intricate home improvement tasks into easy-to-follow steps, Robert is a vital asset to the ToolsWeek community. His well-researched guides and insightful articles have become a go-to resource for both seasoned professionals and eager DIYers looking to enhance their skills and tackle their projects with confidence.

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